1. CRGO silicon steel Uses and Properties
CRGO silicon steel is a key material in the electrical industry due to its excellent magnetic
properties, low energy losses, and high efficiency in electrical devices. Its unique characteristics
make it a preferred choice for applications where high performance and energy efficiency are
essential. Cold Rolled Grain Oriented Steel (CRGO) is a specialized type of electrical steel
designed for use in transformers, motors, and other electrical equipment. It is produced through a
cold rolling process that aligns the crystal grains of the steel in a specific direction, resulting in
improved magnetic properties. CRGO steel exhibits high magnetic permeability, low core losses,
and excellent magnetic flux density, making it ideal for applications requiring efficient energy
transfer and minimal electrical losses.
Key Features of CRGO Silicon Steel
CRGO silicon steel is a specialized material used primarily in the cores of transformers and other
devices where efficient magnetic performance is crucial. Here are the key features that make
CRGO silicon steel particularly valuable:
1. High Magnetic Permeability
CRGO steel has very high magnetic permeability, which allows it to support a high magnetic
flux density with minimal energy loss. This feature is essential for transformers and other
magnetic cores to operate efficiently.
2. Low Core Loss
One of the most critical features of CRGO silicon steel is its low core loss, which includes both
hysteresis and eddy current losses. This low loss improves the efficiency of electrical
transformers, particularly under high-frequency operating conditions.
3. Grain Orientation
The grains in CRGO silicon steel are oriented in the direction of rolling. This orientation
significantly enhances the steel’s magnetic properties in the rolling direction, which is a crucial
factor in reducing losses in transformers.
4. High Electrical Resistivity
The addition of silicon increases the electrical resistivity of the steel. Higher resistivity helps in
reducing eddy current losses, which are proportional to the square of the material’s thickness and
inversely proportional to its resistivity.
5. Thermal Stability
CRGO maintains its properties over a range of temperatures, making it suitable for various
operating conditions. This stability ensures consistent performance, which is vital for
applications involving significant temperature variations.
6. Mechanical Durability
While it is less ductile compared to other steels, CRGO still offers sufficient mechanical strength
and durability for handling and assembly into cores without significant material degradation.
7. Cost-effectiveness
2. Despite its higher initial cost compared to non-oriented silicon steel, the superior efficiency and
performance of CRGO can lead to overall cost savings in energy consumption and maintenance
in long-term applications.
Applications of CRGO Silicon Steel
CRGO silicon steel is a specialized electrical steel that has been processed to enhance its
magnetic properties. This type of steel is particularly crucial in the production of electrical
equipment due to its excellent magnetic characteristics, low core losses, and improved
efficiency. Here are some key applications of CRGO silicon steel:
Transformers: CRGO silicon steel is widely used in the core of power and distribution
transformers, where its low hysteresis losses help improve energy efficiency.
1. Role of CRGO steel in transformer cores:
CRGO steel is widely employed in the construction of transformer cores owing to its excellent
magnetic properties. The grain orientation of this steel aids in reducing energy losses by
minimizing eddy currents, rendering it highly efficient for power transmission and distribution.
The low core loss and high magnetic permeability of CRGO steel contribute to improved
transformer performance.
2. Advantages of employing CRGO steel in transformer cores:
The utilization of CRGO steel in transformer cores offers several advantages. Firstly, its low core
loss properties result in reduced energy wastage and improved overall efficiency. Secondly, the
high magnetic permeability of CRGO steel allows for compact and lightweight transformers.
Additionally, the superior magnetic characteristics of CRGO steel ensure minimal hysteresis
losses, thereby enhancing the reliability and longevity of the transformer.
2. Electric Motors: CRGO silicon steel is utilized in the stator and rotor cores of electrical
motors, providing high efficiency and performance in both industrial and consumer applications.
A. Use of CRGO steel in electric motor laminations:
CRGO steel is extensively employed in the construction of electric motor laminations. These
laminations are stacked together to form the motor’s core, which plays a crucial role in
converting electrical energy into mechanical energy. The use of CRGO steel laminations aids in
reducing energy losses caused by eddy currents, ensuring efficient motor operation.
B. Benefits of CRGO steel in electric motors:
The utilization of CRGO steel in electric motors provides several benefits. Firstly, it helps
improve the motor’s efficiency by minimizing core losses. This results in increased power output
and reduced energy consumption. Secondly, CRGO steel laminations contribute to reduced noise
3. and vibrations, thereby enhancing the motor’s overall performance. Additionally, the high
magnetic permeability of CRGO steel allows for compact motor designs, making them suitable
for various applications.
3. Inductors and Chokes: Inductors, transformers, and chokes in AC and DC applications use
CRGO silicon steel to reduce losses and improve performance in power electronics. The use of
A. Importance of CRGO steel in inductors and chokes:
CRGO steel plays a significant role in the manufacturing of inductors and chokes. These
components are essential in various electronic devices and power systems for energy storage and
filtering applications. The unique magnetic properties of CRGO steel enable efficient energy
transfer and minimize losses, making it an ideal material for inductor and choke cores.
B. Advantages of CRGO steel in inductors and chokes:
Using CRGO steel in the construction of inductors and chokes offers several advantages. The
low core loss characteristics of CRGO steel ensure high energy efficiency, resulting in improved
device performance. Additionally, the high saturation flux density of CRGO steel allows for
compact and lightweight designs, making it suitable for space-constrained applications.
Moreover, the excellent magnetic properties of CRGO steel contribute to stable inductor and
choke operation, ensuring reliable performance.
4. Generators: In generators for power plants and renewable energy sources, CRGO silicon steel
is employed to enhance efficiency by minimizing energy losses.
5. Magnetic Sensors: CRGO silicon steel can be found in magnetic sensors and other electronic
devices where magnetic properties are essential for functionality.
6. Reactor Cores: In nuclear reactors, CRGO silicon steel may be used in certain magnetic
components to enhance performance and safety.
7. Home Appliances: Some household appliances, such as fans, refrigerators, and pumps, often
use CRGO silicon steel in their motors to enhance energy efficiency.
8. Specialized Industrial Equipment: CRGO silicon steel is applied in various industrial
machinery that requires efficient magnetic performance to minimize operational costs and
improve durability.
Overall, CRGO silicon steel is a critical material in modern electrical engineering, contributing
to the efficiency and effectiveness of numerous electrical machines and devices.
4. a
Efficiency and performance benefits of CRGO steel
CRGO (Cold Rolled Grain Oriented) steel offers numerous advantages in terms of efficiency and
performance. This article shall delve into the intricacies of two key aspects: the reduction of
energy losses and the magnetic properties of CRGO steel.
A. Reduction of energy losses
1. How CRGO steel minimizes energy losses:
CRGO steel is ingeniously crafted to minimize energy losses in electrical transformers. Its
unique grain orientation allows for improved magnetic properties, thereby reducing the core
losses that occur during the transformer’s operation. By employing CRGO steel, transformers
can achieve heightened energy efficiency and lower power consumption.
2. Impact of CRGO steel on energy efficiency:
5. The utilization of CRGO steel in transformers bears a significant impact on energy efficiency. In
comparison to other varieties of electrical steel, CRGO steel offers lower core losses, resulting in
diminished energy wastage and an enhanced overall efficiency. This ultimately translates to
substantial cost savings and a more sustainable energy infrastructure.
B. Magnetic properties
1. Magnetic characteristics of CRGO steel:
CRGO steel exhibits remarkable magnetic properties owing to its meticulous grain orientation.
The grains are meticulously aligned in a specific direction during the manufacturing process,
rendering the material with high magnetic permeability and minimal magnetic losses. This
facilitates efficient energy transfer and mitigates the heat generated within the transformer.
2. Contribution of CRGO steel to magnetic performance:
The utilization of CRGO steel in transformer cores augments the magnetic performance of the
system. Its low hysteresis loss and eddy current loss properties ensure minimal energy
dissipation, thereby enabling efficient power transmission. This heightened magnetic
performance not only amplifies the overall efficiency of transformers but also prolongs their
lifespan.
The Cost-effectiveness and Sustainability of CRGO Steel:
CRGO steel, also known as electrical steel, possesses numerous cost-effective and sustainable
advantages in comparison to conventional steel materials. A. Long-term cost savings: 1.
Financial advantages of employing CRGO steel: CRGO steel is specifically engineered for
electrical applications, offering diminished core losses and enhanced magnetic properties. This
translates into reduced energy consumption and increased efficiency, resulting in long-term cost
savings for industries reliant on electrical equipment. Moreover, the superior magnetic properties
of CRGO steel enable the creation of smaller and lighter transformers, thereby reducing material
and transportation costs. 2. Potential return on investment with CRGO steel: Though the initial
investment in CRGO steel may surpass that of traditional steel, the long-term benefits outweigh
the upfront expenses. The energy savings and operational efficiency achieved with CRGO steel
can lead to a significant return on investment over the lifespan of the equipment.
B. Environmental benefits:
1. Sustainable aspects of CRGO steel: CRGO steel is manufactured using a process that
minimizes waste and utilizes recycled materials. This renders it a sustainable choice for
6. industries aiming to diminish their environmental impact. Furthermore, the longevity and
durability of CRGO steel contribute to its sustainability, as it necessitates less frequent
replacement compared to other materials.
2. Contribution to reducing carbon footprint: By employing CRGO steel, industries can actively
contribute to reducing their carbon footprint. The energy-efficient properties of CRGO steel
result in lower energy consumption during the operation of electrical equipment, leading to
diminished greenhouse gas emissions. Additionally, the utilization of recycled materials in the
manufacturing process further reduces the carbon footprint associated with the production of
CRGO steel.
Advantages of CRGO Steel
Enhanced magnetic properties for efficient energy conversion
Cold rolled grain-oriented steel offers enhanced magnetic properties that are specifically
engineered for efficient energy conversion in electrical applications. Its unique grain orientation
and composition result in high magnetic permeability, allowing for the efficient transfer of
magnetic flux. This characteristic enables transformers, electric motors, and generators equipped
with CRGO steel cores to achieve optimal energy conversion with minimal losses, ultimately
leading to improved overall system efficiency.
Reduction of core losses and improved performance
One of the primary advantages of CRGO steel is its ability to significantly reduce core losses in
electrical devices. By minimizing eddy current and hysteresis losses, cold rolled grain-oriented
steel cores experience lower energy dissipation during operation. This reduction in core losses
results in improved performance and efficiency of transformers, motors, and generators, as more
electrical energy is converted into useful output with less waste. Consequently, electrical
equipment utilizing CRGO steel demonstrates enhanced reliability, stability, and longevity in
service.
Impact of CRGO steel on overall system efficiency
The utilization of CRGO steel profoundly impacts the overall efficiency of electrical systems. It
optimizes energy conversion and minimizes losses, enabling transformers, motors, and
generators to operate efficiently across various conditions. This reduces energy consumption,
cuts operating costs, and enhances environmental sustainability in power generation and
transmission. Furthermore, CRGO steel’s superior efficiency improves grid stability, voltage
regulation, and power quality, ensuring reliable electricity supply.
No Load Losses in Transformer
What are No-Load Losses in Transformers?
7. No load losses occur when the transformer is energized at the rated voltage and frequency,
keeping its secondary open circuit. Transformer no-load losses occur because of the magnetic
field.
Transformer no-load losses are combined losses caused by eddy current loss, hysteresis loss,
stray eddy current loss, and dielectric loss. The maximum losses when the transformer is under
no load occur in the core. Therefore, the No-Load losses of the transformer are also called iron
loss or excitation loss. Transformer no-load losses are constant from no load to full load;
therefore, no-load losses are also called constant losses.
A transformer is a static device, and there are no moving parts in the transformer. Therefore, the
friction and windage losses in the transformer are nil. The transformer steps up or steps down the
voltage, keeping the frequency unaltered. Transformer load losses and no load losses occur
because of the current flowing in the winding and magnetic field in the core.
For an ideal transformer, the input power is equal to the output power, however, in reality, this is
not true. The output power of the transformer is always less than the input power. The energy
can neither be created nor it can be destroyed; the same principle is applicable to the energy
balancing of the transformer as well.
The power drawn at the primary is equal to the losses in the transformer plus the power delivered
at the secondary side of the transformer.
Types of Losses in a Transformer
The losses in the transformer can be broadly categorized into two categories;
1. Iron losses or core losses, dielectric loss, and stray eddy current loss
2. Copper loss and Stray losses
Types of No-Load Losses in Transformer
The voltage applied at the primary winding produces a magnetic field in the core. The flux
produced due to the primary current passes through the core, gets linked to the secondary
winding of the transformer, and induces a voltage in the secondary of the transformer.
In this induction process, when the transformer is at no load, it suffers from iron or core losses
that can be further categorized into two categories: hysteresis loss, eddy current loss, stray eddy
current loss, and dielectric loss. All these losses are constant, and therefore, the no-load losses
are also called constant losses of the transformer.
Hysteresis Loss
When the voltage is applied to the primary of the transformer, the alternating current flowing in
the primary magnetizes the core. The core goes under the magnetization and demagnetization
process because of the flow of current in the forward and reverse directions. With the reversal of
8. the direction of the alternating current, the energy is lost in the form of heat in the core. The heat
loss due to the repeated reversal of the magnetic field in the core is known as hysteresis loss.
The hysteresis loss can be calculated by finding the area of the B-H curve. To minimize
hysteresis loss, the transformer’s core is made of Cold-Rolled Grain-Oriented (CRGO) Silicon
Steel because this material’s magnetization curve area is less than that of other magnetic
materials.
The hysteresis loss in the transformer core can be calculated using the following formula.
Eddy Current Loss
The flux that passes through the core induces a voltage of different magnitudes at various places
on the surface of the core and the other conducting parts of the transformer. Because of potential
9. differences at various places on the core surface, the current setup in the core. These currents set
up in the core are called eddy currents.
Because of eddy currents, heat loss equal to I2
R loss occurs in the core.
The eddy current loss depends on the square of the current flowing in the upper part of the
core and the resistance of the core material. The solid sheet of the iron block has less resistance
because of the larger cross-section area. The magnitude of the voltage induced in a solid block is
higher, and as a result, the eddy current loss is higher in the solid iron block.
The eddy current in the transformer can be calculated using the following formula.
10. Dielectric Loss
Dielectric loss occurs in the insulation materials of the transformer due to the alternating voltage
stress. This loss is usually minimal but becomes significant in high-voltage transformers.
Magnetostriction Loss
Magnetostriction loss occurs due to the physical expansion and contraction of the core material
under the influence of the alternating magnetic field. This results in mechanical energy loss,
which is perceived as the characteristic humming sound of transformers.
How to Reduce No Load Losses in Transformers?
Reducing no-load loss in a transformer improves its efficiency and minimizes energy waste.
1. Use cold-rolled grain-oriented (CRGO) silicon steel to reduce core losses.
2. Consider advanced core materials like amorphous steel, which has lower hysteresis loss.
Amorphous metal has very thin laminations (about 0.025 mm), reducing eddy current
loss significantly compared to CRGO steel.
3. Heat treatment (annealing) of the core improves its magnetic properties, reducing
hysteresis loss.
11. 4. The core should be made of thin, insulated laminations to increase resistance and limit
eddy current circulation.
5. Using high-resistivity materials, such as silicon steel, reduces eddy currents.
6. Use low-loss insulation materials like epoxy resin, Nomex, or transformer oil with high
dielectric strength.
7. Keep insulation dry and free from contaminants to avoid increased dielectric losses.
How does the thin laminated core reduce the no-load losses in a transformer?
The iron core is formed using several thin electrically insulated sheets called lamination to
minimize the eddy current losses.
The area of the eddy current path gets reduced, and the losses decrease because of the decrease in
induced voltage and increase in resistance. The thin laminated sheet has higher resistance. The
flow of eddy current in laminated sheets is given below.
The current flowing in the sheet is equal to;
I = Potential difference of the EMF induced in laminated core/Resistance of the sheet.
12. As the thin sheet has higher resistance than the thick sheet, the current flowing through the thin
sheet is very low compared to the current flowing through the thick sheet. With the reduction in
the magnitude of the eddy current in thin stamping, the eddy current loss reduces drastically.
That is why the core of the transformer is made of thin laminated sheets.
Difference between Transformers no load losses and load Losses
In a transformer, no-load losses refer to energy losses occurring in the core even when no current
flows through the windings. These losses, also called core losses or iron losses, are caused by
hysteresis and eddy currents due to the alternating magnetic field. Load losses, on the other hand,
occur when the transformer is supplying a load and are primarily due to the resistance of the
windings, generating heat as current flows (I²R loss).
Key Differences:
1. Cause of No-Load Losses – Result from hysteresis and eddy currents in the core.
2. Cause of Load Losses – Arise from winding resistance and increase with the current.
3. No-Load Losses are Constant – Remain relatively unchanged regardless of load.
4. Load Losses are Variable – Increase proportionally to the square of the current.
Transformer no-load Loss Percentage
The no-load loss of a transformer typically ranges between 5% and 10% of its rated power.
These losses primarily result from hysteresis and eddy currents in the transformer core.
How to Calculate No-Load Losses in Transformer?
The open circuit test (also called the no-load test) is used to determine the core (iron) losses and
no-load parameters of a transformer. This test is performed with one winding left open while the
other is supplied with rated voltage and frequency.
Since there is no secondary current, the primary current is only responsible for core
magnetization. The power measured by the wattmeter in an open circuit test gives:
Where:
P0 = No-load power (W)
V1 = Applied voltage (V)
I0 = No-load current (A)
13. cosϕ = Power factor at no-load
Effect of Voltage and Frequency Variation on no-load Losses in Transformer
In addition to the dependency of eddy current on the stamping resistance, other electrical
parameters like primary voltage and frequency also affect the eddy current loss.
The transformer is designed for a particular voltage and frequency. The change in supply voltage
and frequency from the designed value will further lead to an increase in eddy current loss. The
transformer manufacturer gives a guarantee for iron loss for the operation of the transformer at
rated voltage and frequency.
The number of magnetic field lines passing through a closed area is called magnetic flux. In
other words, it is the total magnetic field in a given area. Here, the area is the space under
influence of magnetic field lines.
The current flow in an electric circuit. In the same way, the flux flows in a magnetic circuit. Flux
is thus analogous to electric current. The Greek letter Phi or Phi suffix B is its symbol. Its symbol
is Ø and Øm. If the system voltage increases, the maximum flux density in the core increases,
and consequently, the eddy current loss and hysteresis loss increase.
The transformer has two coils wound around a common magnetic core. When an alternating
voltage is applied to the primary coil, current flows through it, producing magnetic flux.
14. The magnetic flux produced in the primary coil is proportional to the ratio of the applied voltage
to the frequency. According to Faraday’s law of electromagnetic induction, the EMF is induced
in the primary. As per Lenz’s law, the induced EMF always opposes the primary current
responsible for producing the EMF.
The following mathematical expression can express the voltage induced in the coil.
E= 4.44 Φf N
Where,
E = Induced EMF in the primary coil
Φ = The magnetic flux
f = Frequency
N = Turns /Phase
The flux travels through the magnetic core, and it gets linked to the secondary coil. Practically,
all the flux produced in the primary does not link to the secondary. Some parts of the magnetic
flux link to the primary coil and other parts of the transformer. The flux that does not link to
primary and secondary coils is the leakage flux. The losses in the transformer increase with an
increase in the leakage flux. The useful flux that links to the secondary coil induces a voltage in
the secondary, according to Faraday’s Law of Electromagnetic Induction. The voltage induced in
the secondary coil is
Es= -N dΦ/dt
15. The secondary voltage remains constant if the rate of change of the flux is constant. It is
desirable that the flux in the transformer must remain constant.
The Flux density of the CRGO Core:
The transformer designer first checks the rated flux density of the colled rolled grain
oriented(CRGO) core. The maximum flux density of the CRGO core is about 1.9 Tesla. If the
flux density of the transformer is above 1.9 Tesla, the core of the transformer gets saturated,
leading to insulation failure of the laminated core. The designed maximum flux density of the
core must be below the maximum rated flux density of the core. The core must not get saturated
in any case. The magnetization curve of the different materials is given below.
The flux density of the core can be controlled during the design stage of the transformer. The
flux density of the core can be controlled by adjusting the cross-sectional area of the core during
transformer design. The flux through the core is the product of the flux density and the cross-
sectional area of the core(Φ=B*A). The flux density of the core can be reduced by increasing the
cross-sectional area of the core.
The voltage induced in the primary when the sinusoidal voltage is applied is
E=4.44 ΦfN
Φ=E/4.44f N
The Number of turns in the primary is constant for a given transformer
Φ=K* E/f
16. Permissible flux density:
The saturation flux density of the Colled rolled grain oriented(CRGO) core is 1.9 Tesla. As per
the present design practice, the peak rated value of the flux density is kept at about 1.7 Tesla,
which is about 0.9 times the rated value. The design margin of 10 % in the flux density is kept to
take care of increased flux density with an increase in the system voltage or a decrease in the
system frequency and the thermal time constant of transformer heated parts.
The maximum over-fluxing in the transformer shall not exceed 110%. The transformer can
continuously operate at 110 % of the designed flux density. However, the operation of the
transformer above 110% and up to 130 % of the flux density can be allowed for a shorter period.
If the flux density increases to 140 %, the transformer shall be tripped instantaneously to avoid
permanent damage.
The table shows the permissible over-fluxing of the transformer.
Over Fluxing (V/f) 1.1 1.2 1.25 1.3 1.4
Duration (Minutes) Continuous 2 1 0.5 0
The over-fluxing protection relay is used to trip the transformer breaker in the condition of over-
fluxing.
To protect the transformer from over-fluxing, the V/F ratio is measured, and the transformer can
be switched off if the flux in the core reaches above the specified flux limit of the transformer.
Eddy current losses drastically increase with an increase in frequency if the voltage is also
increased in the same proportion because the eddy current loss is proportional to the square of
the frequency.
Generally, system frequency remains within the limit of rated frequency +/- 1.5 Hz; however, the
electrical network rich in harmonics can lead to an increase in the eddy current loss. With an
increase in the frequency, the eddy current loss increases much more than the hysteresis loss
because the eddy current loss is proportional to the square of the frequency. In contrast, the
hysteresis loss is proportional to the frequency. We can find the hysteresis loss by calculating the
area of the hysteresis loop.
Thus, the transformer’s no-load losses are equal to the sum of the eddy current loss and the
hysteresis loss.
17. The no-load losses of the transformer are constant for a rated voltage and frequency. Therefore,
the no-load loss is also called a constant loss. The no-load losses change if the transformer is
operated above its rated flux density. Moreover, the increased flux density causes distorted
secondary output voltage, and the transformer, if operated above the rated flux density, is apt to
fail. Therefore, over fluxing protection is employed to protect the transformer.
Variation in Transformer no-load losses with variation in voltage and or frequency
Let us understand how the hysteresis and eddy current loss get affected by changes in frequency
and voltage. We will take four cases to study the no-load losses of transformers.
Case 1: Effect on no-load losses – When the frequency is increased/decreased, keeping voltage
constant
The hysteresis loss is proportional to the frequency, and it increases with an increase in the
frequency. However, the hysteresis loss remains almost unchanged. The reason is that the flux
density in the core decreases in the same proportion as the increased frequency.
Similarly, the hysteresis loss should decrease with a decrease in frequency; however, it remains
almost unchanged because of increased flux density in the core.
The eddy current loss is proportional to the square of the flux density and frequency. With an
increase in the frequency, the eddy current remains unchanged because the product of
B2
m f2
remains unchanged as flux is proportional to the ratio of V/f. With the decrease in
frequency, the flux density in the core increases in the same proportion as the frequency
decreases, and thus, the eddy current loss remains unchanged.
Case 2: Effect on no-load losses- When the voltage is increased/decreased, keeping the
frequency constant
The hysteresis loss is directly proportional to the voltage and flux density. It increases with an
increase in voltage. The magnetic flux density is also proportional to the voltage. Thus, the
hysteresis loss is proportional to the square of voltage if the frequency is kept constant.
Thus,
Hysteresis loss, Wh ∝ V2
Eddy current loss, We ∝ V3
Case 3: Effect on no-load losses – When the frequency is increased/decreased, and voltage is
also increased/decreased in the same proportion
18. If the frequency is increased and voltage is also increased in the same proportion then the flux
density in the core remains unchanged and, in this case, the hysteresis loss will increase
proportionally to the increase of frequency, The eddy current loss will increase in the square
proportion of the increased frequency.
Case 4: Effect on no-load losses – When the frequency is increased/decreased, and voltage is
also increased/decreased in different proportion
In this situation, the eddy current and hysteresis loss will increase or decrease because of the
following reasons.
Increase/decrease of frequency
Increase/decrease of flux density
Dielectric Loss in Transformers
In transformers, dielectric loss occurs in the insulating materials used between the windings and
core. These losses can affect the overall efficiency and longevity of the transformer.
Dielectric Loss in Transformer Formula:
The dielectric loss in transformers can be estimated using the formula: Pd=V2⋅ω⋅C⋅tan
(δ)
Where V is the voltage, ω is the angular frequency, C is the capacitance, and tan
(δ) is the loss
tangent.
Minimizing Dielectric Losses in Transformers:
o Material Selection: Using high-quality, low-loss dielectric materials.
o Design Optimization: Ensuring optimal insulation thickness and material.
o Temperature Control: Implementing cooling systems to manage temperatur
To minimize no-load losses in distribution transformers, several design and operational strategies
can be employed, including using materials with lower core losses, improving core structure and
manufacturing processes, and optimizing operating conditions. These measures can significantly
reduce energy waste and improve the efficiency of the transformer.
Methods for Minimizing No-Load Losses:
1. 1. Core Material Selection:
Use high-quality core materials: Employ silicon steel sheets with lower unit losses.
Utilize amorphous alloys: Consider using amorphous alloys as core materials, which have the
potential to reduce core losses.
19. 2. 2. Core Structure and Manufacturing:
Improve core structure: Design and optimize the core structure to minimize leakage magnetic flux.
Optimize lap connections: Carefully select lap connections to minimize no-load loss.
Reduce core lap width: Minimize the width of core lap to decrease no-load loss.
Optimize iron chip width: Select appropriate iron chip width to reduce core angle weight and no-
load loss.
3. 3. Operational Strategies:
Turn off transformers when standby: Minimize no-load energy losses by switching off transformers
when their generating units are in standby mode.
Optimize parallel operation: For transformers operating in parallel, ensure the best operation mode
is selected and the load is distributed reasonably to minimize total losses.
Stop operation during non-peak periods: If possible, stop the operation of transformers during non-
peak seasons or off-peak hours.
Consider smaller or variable-capacity transformers: For transformers with low average load rates,
consider using smaller-capacity or variable-capacity transformers.
4. 4. Other Measures:
Improve heat dissipation: Use corrugated fuel tanks, chip radiators, or heat pipes to improve heat
dissipation efficiency.
Reduce stray losses: Employ magnetic shielding or electrical shielding to reduce stray losses in the
fuel tank.
Use non-magnetic materials: Use non-magnetic materials as bundling parts or magnetic flux
separators to further reduce stray losses.
Optimize cooling systems: Utilize advanced cooling systems like forced-air or liquid cooling to
effectively dissipate heat and maintain efficiency.
Implement laminating techniques: Transform silicon steel into laminated sheets to slow down the
formation and propagation of eddy currents, thereby reducing losses.
By implementing these measures, no-load losses in distribution transformers can be significantly
reduced, leading to energy savings and improved efficiency.
The transformer constant losses are dependent on the core material. The transformer core
material with reduced losses not only saves power but also extend the transformer life. About 2
to 4% of the power passing through a distribution transformer is recorded as losses. Reducing
no-load losses in a distribution transformer without compromising the performance is the
objective during the design. The development of amorphous alloys and their use as a core
material has been a boon to the utilities that had been relentlessly working on the reduction of
operating costs and losses. Use of an amorphous alloy core in a transformer has the potential to
reduce the no-load core losses. The Finite Element Method is a prominent numerical technique
for dealing with complexity in a variety of ways for low-frequency magnetic circuits. In this
paper, a three-phase distribution transformer 3D-CAD model is examined by the finite element
method to compute and compare the no-load loss. The comparison has been done for a
20. distribution transformer core made of amorphous alloy to that of the conventional cold-rolled
grain-oriented steel. Also, the percentage reduction in each type of no-load loss is assessed.
Methods of reducing no-load loss
After analyzing the no-load loss, the hysteresis loss and eddy current loss of the iron core are
mainly determined by the silicon steel sheet manufacturer, and the additional loss is determined
by the transformer manufacturer. The flux density of core is an important parameter affecting the
no-load loss of transformer core. Therefore, in order to reduce no-load loss, it is necessary to
make the magnetic flux density distribution of each part of the core tend to be uniform, and
reduce the magnetic flux density at the corner of the core on the premise of keeping the effective
cross section of the core unchanged.
1. Staggered seam to three order seam
Because there is a gap at the junction of the transformer core silicon steel sheet, the magnetic
flux suddenly increases through the joint, so the magnetic flux must bypass the gap of the joint
and enter the adjacent laminates through the thin plate. Then part of the magnetic circuit
increases, the reluctance between the sheets increases, and also increases the magnetic density of
the adjacent laminates, resulting in the no-load loss and the increase of the excitation capacity.
The more the number of transformer core joints, the lower the local loss in the joint area, but the
smaller the reduction of local loss. With the increase of the number of joints, the number of iron
core lamination, the working time of silicon steel sheet shearing and iron core lamination and the
processing difficulty of iron core lamination will increase.
In practical application, it is considered that with the increase of the series, the working time of
silicon steel sheet shearing and iron core lamination increases correspondingly, and the
lamination process becomes worse. It is considered that if the three-stage joint is selected and the
appropriate plate type is selected, only one plate type is added to the core column, the process
complexity is slightly increased, and the magnetic function is significantly improved. The three-
stage joint of the core is made of three types of laminates in turn. According to the technical
level of the metallurgical electrical repair enterprise and the magnetic data of the joint, selecting
the three-stage joint is the ideal choice to improve the misconnection of the core.
Taking S9-800/10 and S9-1000/10 power transformers as an example, the same transformer uses
the same planning scheme, structure and materials, and the iron core uses different lap joints.
Four 800kVA staggered joints, three three-level joints, two 1000KVA staggered joints and three
three-level joints were selected.
It can be seen from the test data that the no-load loss of the three-stage joint is 7 percent 8
percent lower than that of the staggered joint under the condition that the cross section of the
core column is unchanged. Only one piece type is added to the three-stage joint core column, and
the working hours of cutting silicon steel sheet and stacking iron core are slightly increased, but
the effect is obvious.
2. Reduce core lap width, reduce core no-load loss
At the corner of the core stack, the overlap width of the joint area between the core column and
the cross yoke has a certain effect on the no {{0}}load function of the transformer. When the
overlap area is large, the area through which the magnetic flux passes increases correspondingly,
and then the no-load loss increases. According to the core model test, the no-load loss of 45
21. degree joint increases by 0.3 percent for every 1 percent increase in lap area. In order to reduce
the no-load loss, it is necessary to study and select the optimal lap area on the premise of
satisfying the mechanical strength.
Changing the connection area of the iron core stack tower can reduce the size of some triangular
holes in the iron core, reduce some magnetic flux density at the triangular holes, and reduce the
no-load loss of the transformer. Our company's original distribution transformer core lamination
Angle is 10mm, but has been changed to 5mm, to achieve a certain effect of consumption
reduction. When the exit Angle of the core lamination is changed from 10mm to 5mm, the cross-
sectional area of the triangular hole at the corner of the core increases, and the magnetic flux
density at the triangular hole inevitably decreases.
3. Reasonable selection of iron chip width, reduce iron core Angle weight, reduce iron core
material, and reduce no-load loss
Core no-load loss is related to core unit loss and core composition, of which the angular weight
is a part. Therefore, the angular quality of iron core not only affects the cost of transformer, but
also directly affects the performance of transformer.
To minimize no-load losses in distribution transformers within a factory, focus on material
selection, core design, and operational practices. Using high-quality, low-loss core materials,
optimizing core geometry, and ensuring proper maintenance are key strategies.
Here's a more detailed breakdown:
1. Material Selection:
High-Grade Core Materials:
Opt for amorphous metal cores or high-quality silicon steel sheets with low hysteresis and eddy
current losses.
Reduce Core Losses:
Utilize amorphous metal cores, which offer superior magnetic properties compared to
traditional silicon steel.
2. Core Design and Manufacturing:
Laminated Core:
Laminate the core to reduce the cross-sectional area and increase resistance to eddy currents.
Optimized Core Geometry:
Reduce the overlapping width of the core and optimize the iron chip width to minimize no-load
loss.
Staggered Joints:
Change the staggered joint to a third-order joint to improve the magnetic circuit and reduce
losses.
3. Operational Practices:
Proper Sizing:
Ensure the transformer is appropriately sized for the load to minimize core losses.
22. Load Balancing:
Efforts to balance the three-phase load of the transformer can also contribute to reduced no-
load losses.
Reactive Power Compensation:
Install reactive power compensation equipment appropriately to minimize no-load losses.
Maintenance:
Regular maintenance and inspection are crucial for identifying and addressing any issues that
could contribute to increased losses.
Cooling Techniques:
Employ effective cooling methods like forced air or liquid immersion to manage winding
losses and keep the transformer at optimal operating temperatures.
4. Additional Considerations:
Magnetic Shielding:
Utilize magnetic shielding or electrical shielding to reduce stray losses and improve the overall
efficiency of the transformer.
Avoid Over-excitation:
Operate the core at a lower flux density to minimize hysteresis losses.
Consider Amorphous Metal Distribution Transformers (AMDTs):
AMDTs, known for their energy-efficient performance, can be an effective solution for
reducing no-load losses.
Tap Adjustments:
Adjust the tap of the transformer in time to maintain optimal operating conditions.
Stray Loss Reduction:
Implement methods like corrugated fuel tanks, chip radiators, and reinforced plastic fans to
improve heat dissipation efficiency and reduce stray losses.
With the introduction of the Bowers Energy Saving Transformer (BEST), our new Amorphous
Core Transformer, we are comparing the transformer cores with the Standard CRGO Core.
Traditionally distribution transformers were made with Cold Rolled Grain Oriented Steel
(CRGO). This is due to its exceptionally high mechanical elasticity and magnetic properties in
the rolling direction. As a result, CRGO transformers have reduced eddy current losses and
increased corrosion resistance over previous-grade steels.
With the introduction of the UK Government’s Net Zero goals and the global efforts to improve
energy efficiency businesses are starting to turn to more environmentally friendly
23. practices. Adapting the Amorphous metal as transformer cores instead of CRGO can further
reduce the losses produced by transformers.
Below is a table of Amorphous vs CRGO materials:
Advantages of Amorphous Core Transformers over Transformers with CRGO Silicon Steel:
1. Low Eddy Current Losses. The thickness of Amorphous Metal is 0.025mm which
results in lower eddy current loss.
2. Less No-Load losses. Due to the random atom structure of the amorphous metal,
friction is reduced when a magnetic field is applied compared to CRGO. This allows
easy magnetization and demagnetization which significantly lowers hysteresis losses,
thus amorphous core significantly reduces core losses which is about 65-75%.
24. 3. Environmental Benefits. Due to the energy savings, there are significant reductions in
greenhouse gas emissions of CO2 and SO2
4. Reduced Aging of Transformer Insulation. Lower temperature rise, slower
deterioration of insulations and hence longer life.
5. Decreased Total Ownership Cost. Although initial investment will be higher, the total
ownership cost over the transformer’s average lifespan of 25-30 years will be
significantly lower than that of CRGO Transformers. This is based on operational and
maintenance costs.
The new Bowers Energy Saving Transformer utilises the development of Amorphous Cores to
produce lower losses.
CRGO Silicon Steel Permeability: Improvement & Measurement
2024-06-27
CRGO (Cold Rolled Grain Oriented) Silicon Steel is a type of electrical steel that’s specifically
designed for use in transformers and other electrical devices where high efficiency is crucial. The
grain orientation of CRGO steel is optimized to provide high permeability and low core loss,
which are essential for efficient energy conversion.
What is CRGO Silicon Steel?
CRGO silicon steel, or Cold Rolled Grain Oriented silicon steel, is a specialized material
thoroughly used in the electric market as a result of its amazing magnetic properties. This steel is
specially engineered to have a high degree of permeability, which makes it extremely effective in
lowering core losses in electrical transformers and other magnetic devices. The manufacturing
process includes cold rolling the steel and then subjecting it to a collection of annealing
treatments, which aligns the grains in the steel in a particular orientation. This grain positioning
is crucial as it dramatically boosts the steel’s magnetic properties, particularly its permeability.
25. The Function of Permeability in CRGO Silicon Steel
Permeability, in the context of CRGO silicon steel, describes the material’s capability to support
the formation of a magnetic field within itself. This property is crucial because it directly impacts
the performance and effectiveness of transformers, inductors, and other electric devices that
depend on electromagnetic fields for their procedure.
CRGO silicon steel is specially crafted to have high permeability, which means it can achieve a
high level of magnetic induction with very little power loss. This is attained with a meticulous
production process that straightens the grains of the steel in certain instructions, maximizing its
magnetic buildings. The high leaks in the structure of CRGO silicon steel permit the creation of
strong magnetic fields with decreased core losses, which is vital for maintaining the performance
of electrical tools.
26. The significance of permeability in CRGO silicon steel can be shown through several essential
efficiency metrics:
Efficiency Metric Impact of High Leaks on the Structure
Magnetic Induction
Greater magnetic induction degrees, result in much more reliable
electromagnetic field creation.
Core Losses
Lowered core losses, resulting in lower energy dissipation and improved
efficiency.
Transformer Effectiveness Enhanced transformer performance due to much better magnetic efficiency.
Magnetizing Current Lower magnetizing current is needed, decreasing the total power consumption.
In a word, the high permeability of CRGO silicon steel is a pivotal factor that boosts the
efficiency of electrical devices by ensuring reliable electromagnetic field creation and decreasing
energy losses. This makes CRGO silicon steel an important material in the electric industry,
especially in the manufacturing of transformers and other magnetic tools.
Factors Affecting the Permeability of CRGO Silicon Steel
The permeability of Cold Rolled Grain Oriented (CRGO) silicon steel is affected by a selection
of factors that are essential to its performance in electric applications. Understanding these
variables is vital for enhancing the product’s magnetic properties and ensuring its efficient usage
in transformers and other electrical gadgets.
1. Grain Orientation
One of the primary factors impacting permeability in CRGO silicon steel is the grain alignment.
Throughout the manufacturing procedure, the grains of the steel are aligned in a specific
direction, which improves the material’s magnetic properties. This placement lowers the power
loss during magnetization and demagnetization cycles, therefore improving the permeability.
2. Purity of the Material
The purity of the silicon steel also plays a crucial role in identifying its permeability. Impurities
such as carbon, sulfur, and oxygen can negatively impact the magnetic buildings of the steel.
High-purity CRGO silicon steel exhibits much better permeability and reduced core losses,
making it a lot more efficient for usage in electric applications.
3. Annealing Process
27. The annealing process is another substantial element that impacts the leaks in the structure of
CRGO silicon steel. Proper annealing assists in eliminating inner anxieties and boosts the grain
orientation, thereby enhancing the product’s magnetic properties. The temperature and period of
the annealing procedure should be thoroughly controlled to attain ideal outcomes.
4. Thickness
The thickness of the CRGO silicon steel sheets can also affect their permeability. Thinner silicon
steel typically shows higher leaks in the structure and reduced eddy current losses, which is
advantageous for high-frequency applications. Nonetheless, there is a compromise between
mechanical strength and magnetic efficiency that must be thought about.
5. Magnetic Domain Structure
The magnetic domain name framework of the CRGO silicon steel is another essential factor
affecting its permeability. Domain name refinement strategies, such as laser cutting or
mechanical scribing, can be utilized to lower the dimension of magnetic domain names. This
improvement brings about decreased core losses and boosted permeability.
6. Temperature
The operating temperature of CRGO silicon steel can also affect its permeability. Raised
temperature levels might create adjustments in the product’s magnetic properties, potentially
leading to reduced permeability. As a result, it is vital to think about the thermal security of the
steel in its intended application.
In summary, the permeability of CRGO silicon steel is affected by a mix of variables including
grain alignment, material pureness, annealing process, steel thickness, magnetic domain name
structure, and operating temperature level. Recognizing and optimizing these factors is crucial
for improving the performance of CRGO silicon steel in different electric applications.
28. Enhancements in CRGO Silicon Steel for Improved Permeability
To accomplish improved permeability in CRGO silicon steel, several developments and methods
have been developed. These improvements focus on refining the product’s microstructure and
optimizing its magnetic buildings. Here will certainly look into the key methods and
advancements that have contributed to boosting the permeability of CRGO silicon steel.
1. Grain Positioning
One of the main aspects affecting the permeability of CRGO silicon steel is the positioning of its
grains. Advanced making techniques make sure that the grains are aligned towards the magnetic
change, which substantially reduces energy losses and enhances leaks in the structure. This exact
grain alignment is accomplished through managed rolling and annealing processes.
2. Purity of Raw Materials
29. The pureness of the raw materials used in the production of CRGO silicon steel plays a critical
duty in establishing its leaks in the structure. By minimizing pollutants such as carbon, sulfur,
and oxygen, manufacturers can generate steel with greater magnetic properties. Using high-
purity iron and silicon is necessary for attaining optimum permeability.
3. Annealing
The annealing process is essential in improving the permeability of CRGO silicon steel. This
heat treatment procedure aids in relieving internal stresses and improving the grain framework.
The controlled ambiance during annealing, typically involving a combination of hydrogen and
nitrogen, guarantees that the steel accomplishes the desired magnetic properties.
4. Insulation Coatings
Using top-quality insulation layers to CRGO silicon steel can considerably boost its
permeability. These coatings reduce eddy current losses and boost the overall magnetic
performance of the steel. Typically used coatings include magnesium oxide (MgO) and
phosphate-based coatings, which provide superb insulation and defense.
5. Laser Cutting
Laser cutting is a cutting-edge technique used to boost the permeability of CRGO silicon steel.
This process includes creating fine and precise lines on the surface of the steel, which aids in
lowering magnetic losses by improving domain name wall surface activity. Laser cutting has
been shown to dramatically boost the permeability and general efficiency of CRGO silicon steel.
6. Tension Alleviation Techniques
Recurring stresses in CRGO silicon steel can negatively influence its permeability. Carrying out
anxiety relief techniques, such as regulated cooling and additional annealing actions, can assist in
reducing these stress and anxieties. By minimizing residual tensions, the magnetic buildings of
the steel are improved, resulting in boosted leaks in the structure.
7. Advanced Alloying
Integrating particular alloying elements can better enhance the permeability of CRGO silicon
steel. Elements such as aluminum, boron, and nitrogen are added in regulated total up to improve
the magnetic properties. These alloying aspects aid in fine-tuning the grain framework and
reducing power losses.
Enhancement Technique Effect on Permeability
Grain Orientation Reduces power losses, improves leaks in the structure
30. Pureness of Raw Products Higher magnetic properties
Annealing Process Fine-tunes grain structure eliminates internal stresses
Insulation Coatings Decreases eddy current losses
Laser Cutting Enhances domain wall surface movement
Anxiety Alleviation Techniques Minimizes recurring stresses
Advanced Alloying Improves grain structure, reduces energy losses
To conclude, improving the permeability of CRGO silicon steel includes a combination of
advanced production techniques, high-purity basic materials, and cutting-edge processes. By
concentrating on these key areas, makers can produce CRGO silicon steel with remarkable
magnetic buildings, making it important for applications requiring high efficiency and reduced
power losses.
Techniques to Gauge Permeability of CRGO Silicon Steel
Gauging the permeability of CRGO silicon steel is vital for examining its performance in
numerous applications, specifically in electric transformers and other magnetic gadgets.
Numerous techniques are utilized to identify the magnetic permeability of CRGO silicon steel,
each with its very own collection of benefits and restrictions. Here will certainly talk about a few
of the most extensively used techniques.
1. Epstein Structure Method
The Epstein framework method is a basic strategy used to measure the magnetic properties of
electrical steels, including CRGO silicon steel. This approach entails winding the steel sample in
a detailed configuration within a framework, permitting exact control and measurement of the
electromagnetic field and change thickness. The crucial parameters determined include:
Specification Description
Electromagnetic Field (H) Toughness of the used magnetic field
Magnetic Flux Thickness (B) Quantity of magnetic flux in each location
2. Solitary Sheet Tester (SST)
The Single Sheet Tester (SST) is another method used to determine the magnetic properties of
CRGO silicon steel. This method entails placing a single silicon steel sheet in a test apparatus
31. that uses a magnetic field and measures the resulting magnetic change. The SST approach is
specifically helpful for reviewing the performance of individual sheets and can provide
comprehensive information on:
Specification Summary
Core Loss Energy loss in the steel as a result of hysteresis and eddy currents
Magnetic Permeability Proportion of magnetic change thickness to magnetic area stamina
3. Vibrating Sample Magnetometer (VSM)
The Vibrating Sample Magnetometer (VSM) is a very delicate technique utilized to measure the
magnetic properties of materials, including CRGO silicon steel. In this technique, a small
example is subjected to a differing electromagnetic field while its magnetization is measured.
The VSM can provide accurate dimensions of:
Specification Summary
Magnetic Hysteresis Loop
Graph showing the partnership between electromagnetic field and
magnetization
Coercivity The strength of the electromagnetic field needed to reduce magnetization to no
4. B-H Curve Tracer
The B-H Contour Tracer is an instrument developed to measure the B-H curve of magnetic
materials, including CRGO silicon steel. This device applies an electromagnetic field to the
example and determines the resulting magnetic flux density, permitting the construction of the B-
H curve, which is crucial for comprehending the product’s magnetic actions. Key dimensions
include:
Criterion Description
Preliminary Permeability Magnetic leaks in the structure at low magnetic area toughness
Maximum Permeability Highest worth of permeability attained
Each of these techniques gives beneficial insights into the permeability of CRGO silicon steel,
assisting to guarantee that the product fulfills the strict needs of its intended applications.
Permeability: CRGO Silicon Steel vs Other Silicon Steels
32. CRGO silicon steel is particularly crafted to show high permeability in the rolling direction. This
is attained with a precise production process that straightens the grains in the steel, minimizing
hysteresis loss and enhancing magnetic properties. On the other hand, cold rolled non grain
oriented silicon steel (CRNGO) does not have this grain positioning, causing lower permeability
values and greater core losses.
Properties CRGO Silicon Steel CRNGO Silicon Steel
Permeability (μ) High (up to 40,000 μ) Modest (up to 15,000 μ)
Core Loss Reduced Higher
Magnetic Saturation High Modest
Applications Transformers, High-efficiency motors General electrical motors, Generators
Another essential element that distinguishes CRGO from other silicon steels is its ability to keep
high permeability across a series of running frequencies. This makes CRGO silicon steel
specifically ideal for high-frequency applications where keeping efficiency and decreasing losses
are extremely important. On the other hand, CRNGO silicon steel tends to show a decrease in
leaks in the structure at higher frequencies, limiting its efficiency in such applications.
Additionally, the texture coefficient, which evaluates the level of grain alignment, is
substantially higher in CRGO silicon steel compared to other silicon steels. This greater texture
coefficient even more adds to its premium magnetic properties, making it the material of
selection for lots of innovative electric applications.
FAQs about CRGO Silicon Steel Permeability
1. What is CRGO Silicon Steel?
Cold Rolled Grain Oriented (CRGO) silicon steel is a specialized material extensively used in
the electrical industry due to its remarkable magnetic properties. This steel is specifically
engineered to have a high degree of permeability, which makes it highly efficient in reducing
core losses in electrical transformers and other magnetic devices.
2. What is the Role of Permeability in CRGO Silicon Steel?
The permeability of Cold Rolled Grain Oriented (CRGO) silicon steel is a critical attribute that
significantly influences its performance in electrical applications. Permeability, in the context of
CRGO silicon steel, refers to the material’s ability to support the formation of a magnetic field
within itself. This property is essential because it directly impacts the efficiency and
33. effectiveness of transformers, inductors, and other electrical devices that rely on magnetic fields
for their operation.
3. How to Enhance the CRGO Silicon Steel Permeability?
To achieve improved permeability in CRGO (Cold Rolled Grain Oriented) silicon steel, several
advancements and techniques have been developed. They include grain orientation, raw material
pureness, annealing, coating, laser cutting, etc.
4. How to Measure the Permeability in CRGO Silicon Steel?
Measuring the permeability of CRGO silicon steel is crucial for assessing its performance in
various applications, especially in electrical transformers and other magnetic devices. Several
methods are employed to determine the magnetic permeability of CRGO silicon steel, each with
its own set of advantages and limitations. These methods include the epstein structure method,
solitary sheet tester (SST), vibrating sample magnetometer (VSM), B-H curve tracer, etc.
No-load losses in a transformer, also known as core losses, typically range from 5% to 10% of
the transformer's rated power. These losses, which occur even when no load is connected to the
transformer, are primarily due to hysteresis and eddy currents in the core material. Properly
constructed transformers usually have total losses (no-load and load losses combined) between
0.3% and 0.5% of their rated kVA, with no-load losses accounting for 25-35% of the total.
Elaboration:
No-load losses:
These losses occur when the transformer is energized but not delivering power to a load. They
are caused by:
Hysteresis losses: These losses arise from the magnetic material's resistance to changes in the
magnetic field, as the core's magnetic domain orientations are constantly flipping as the voltage
varies.
Eddy current losses: These losses occur due to circulating currents induced in the core by the
changing magnetic field.
Load losses (on-load losses):
These losses occur when the transformer is delivering power to a load. They are primarily due
to the resistance of the transformer windings (I²R losses), which causes energy to be converted
into heat.
Importance of minimizing no-load losses:
Reducing no-load losses improves transformer efficiency and reduces energy waste.
No-load loss testing:
No-load loss testing is a routine factory acceptance test for power transformers, ensuring they
meet specified performance requirements, according to a LinkedIn article. If the measured no-
34. load loss is significantly above the guaranteed value, the transformer may be rejected or a
reduction in cost imposed.
Product Description
Silicon steel, also known as silicon steel Sheet or Electrical Steel, it is a ferro-silicon soft
magnetic alloy steel with very low carbon content, usually containing 0.5% to 4.5% silicon. The
addition of silicon can increase the resistivity and maximum permeability of iron to reduce the
coercivity, iron loss and magnetic aging.
The difference between oriented silicon steel and non-oriented silicon steel
Non-oriented silicon steel: ferro-silicon alloy with very low carbon content. In the deformed and
annealed steel sheet, its grains are distributed randomly. The silicon content of the alloy is 1.5%
to 3.0%, or the sum of the silicon and aluminum content is 1.8% to 4.0%. The products are
usually cold-rolled plates or strips, which are mainly used to manufacture motors and generators.
2400-3500USD
Important Electrical Properties of CRGO Cold Rolled Grain Oriented Steel & Hi - B CRGO
Grades
Core Loss Details of Popularly used CRGO Electrical steel.
Manufacturing mills of CRGO Grain Oriented Electrical Steel guarantee the Core Loss figure at
flux density of 1.5 Tesla in Case of CRGO Conventional Grain Oriented Electrical Steel Grades
and in Case CRGO HIB Grades and CRGO HIB LS Electrical Steel at 1.7 Tesla,50 HZ.
Thickness
MM
CRGO Grade Assumed Maximum Core Loss Minimum
Induction
at 800 A /
m T
KG/DM3 At 1.5T At 1.7T
37. M-6 1.11 1.57 1.8
Technical Details of CRGO
CRGO Cold Rolled Grain Oriented Electrical Steel is available in various grades (Generally
called M3, M4, M5 & M6). Followed link below “more grades of CRGO” for Major
international standards such as Japanese (JIS), American (ASTM), German (DIN) and British
Standards which specify CRGO grade and Thickness.
Important physical properties of CRGO Steel
Density gm/c3 7.65
Silicon content % 3.10
Resistivity micro Ohm-centimeter 48.00
Ultimate Tensile Strength 0° to Rolling Direction Kg/mm2 32.60
Ultimate Tensile Strength 90° to Rolling Direction Kg/mm2 38.20
Stacking factor % M4 (.27 mm) 96.00
Stacking factor % M5 (.30 mm) 96.50
38. Stacking factor % M6 (.35 mm) 97.00
CRGO materials come either in the form of coils or sheets. Given below the details of
dimensions and tolerances as per JIS C 3553.
Dimensions and Tolerances of CRGO Electrical Steel
CRGO MOTHER
COILS
Thickness
0.18 mm (0.0071 in. )
0.20 mm (0.0079 in.), 0.23 mm
(0.0091 in. )
0.27 mm (0.0106 in.), 0.30 mm
(0.0118 in. )
0.35 mm (0.0138 in.)
Width
(Standard width available
with range)
914 mm (36 in.), and 1000 mm
(39 in. )
from 50 mm(2 in.), to 1.050mm
(41 in. )
Inside Coil Diameter 508 mm (20 in. )
CRGO Sheets Thickness 0.30 mm (0.0118 in.), 0.35 mm
(0.0138 in. )
39. Width
914 mm (36 in.), and 1000 mm
(39 in. )
Length
Length will be available
according to negotiation
CRGO Grain Oriented Electrical Steel Tolerances in Dimensions & Shape of CRGO Steel
Conform to JIS C 2553.
Width
mm
Thickness
mm
TOLERANCE
Thickness
mm
Deviation
of
thickness
in
transverse
direction
mm
Width
mm
Camber
in any 2
metres
(Slit
Products)
mm
Shear
Burr
mm
150
or
under
0.18
0.20
0.23
0.27
0.30
0.35
+0.02
+0.02
+0.02
+0.03
+0.03
+0.03
0.02 or
under
+0.20
1.0 or
under
0.04
or
under
over
150
to 400
0.18
0.20
0.23
0.27
0.30
0.35
+0.02
+0.02
+0.02
+0.03
+0.03
+0.03
0.02
or under
+0.30
40. over
400
to 750
0.18
0.20
0.23
0.27
0.30
0.35
+0.02
+0.02
+0.02
+0.03
+0.03
+0.03
0.03
or under
+0.50
over
750
0.18
0.20
0.23
0.27
0.30
0.35
+0.02
+0.02
+0.02
+0.03
+0.03
+0.03
0.03
or under
+0.6
0
Note : Stipulation of camber shall be applied only for the crgo steel strips (width 75mm
over).
Besides the Watt Losses of CRGO at specific flux densities of 1.5 T and 1.7 T CRGO
manufacturers also give curves of indicating Watt Losses ad A.C. Magnetization at various flux
densities. These curves are of immense help to Transformer designers, and available on customer
request.
Conventional CRGO Grades Generally M3, M4, M5, M6 are used regularly for Transformer
Cores in Transformers. However recently due to environmental protection, energy savings are
becoming a very important factor and minimizing core loss in Transformers is becoming a
must.Nippon Steel Corporation JAPAN has come out with low loss Hi-B Grades materials,which
guarantee low Watt Losses at 1.5 Tesla flux density. Such materials are called CRGO Hi-B
materials. Table 3 gives magnetic properties of CRGO Hi-B material. Popular Hi-B grades used
in India are 23 MOH and 27 MOH.
Hi – B CRGO MATERIALS :
Thickness Grade Core Loss Lamin
ation
Factor
42. 27ZD
KH95
0.95 0.65 0.88 0.39 0.52 1.91
27ZD
MH90
0.90 0.62 0.84 0.38 0.53 1.91
97.9
27ZD
MH95
0.95 0.65 0.88 0.39 0.53 1.91
27ZH9
5
0.95 0.69 0.93 0.41 0.55 1.91
98.1
27M-
OH
1.03 0.72 0.99 0.43 0.59 1.91
27M-
1H
1.09 0.74 1.03 0.44 0.61 1.91
0.
30
1
2
30ZH1
00
1.00 0.73 0.98 0.44 0.58 1.92
98.3
30M-
OH
1.05 0.74 1.01 0.44 0.60 1.91
0.
35
1
1
35M-
1H
1.16 0.85 1.13 0.52 0.68 1.92 98.5
No-load losses in a transformer, often called core losses or iron losses, are primarily due to the
energy wasted in the core material. CRGO (Cold Rolled Grain-Oriented) core is a common
material for transformer cores, but it's not the only option. Amorphous metal cores, for example,
43. are known for significantly reducing no-load losses compared to CRGO. The selection of core
material, including CRGO, is a crucial design decision that impacts transformer efficiency and
cost.
Here's a more detailed look:
1. No-load Losses and Their Causes:
No-load losses occur even when no current is flowing in the secondary winding.
These losses are primarily caused by the magnetic field oscillating within the core.
Hysteresis loss and eddy current loss are the main components of no-load losses.
Hysteresis loss is due to the energy required to realign the magnetic domains in the core material
with each magnetic cycle.
Eddy current loss is caused by induced currents in the core material, which create heat.
2. CRGO Core (and its Limitations):
CRGO steel is a common material for transformer cores due to its high magnetic permeability
and low hysteresis loss.
CRGO laminations are often used to reduce eddy current loss.
While CRGO is effective, it's not the most efficient option for minimizing no-load losses.
CRGO cores can have higher no-load losses compared to amorphous metal cores.
3. Amorphous Metal Cores (and their Advantages):
Amorphous metal cores offer lower no-load losses compared to CRGO cores.
They have a random grain structure, which reduces hysteresis loss.
Their high resistivity and thin film thickness (about 1/10th of CRGO) reduce eddy current loss.
Amorphous core transformers can have 70-80% lower no-load losses than CRGO core
transformers of the same rating.
4. Factors Affecting No-load Loss:
Core Material: Different materials have different magnetic properties and thus different no-load
loss characteristics.
Lamination Thickness: Thinner laminations reduce eddy current losses.
Core Joint Size: A smaller core joint can reduce no-load losses, but it needs to be balanced with
manufacturing costs and steel usage.
Operating Voltage: Higher voltages can increase no-load losses.
5. Selecting Core Material:
The choice of core material depends on factors like desired efficiency, cost, and application.
For high-efficiency applications with a focus on minimizing no-load losses, amorphous metal
cores are often preferred.
For applications where cost is a primary concern, CRGO cores may still be a viable option.
44. Consult industry standards and guidelines for specific requirements and recommendations.
No load lose in Transformer
51. Core Losses in Transformers
2024-07-30 10:06:45
Any electrical equipment experiences losses over prolonged operation, and
power transformers are no exception.
1.Definition and Principle Unlike copper losses, core losses in transformers are independent of
the windings and current magnitude. Core losses, also known as “no-load losses,” are related to
the transformer’s iron core and occur whether the transformer is under full load or no load. These
losses are a fixed component of transformer losses. However, during operation, power loss
decreases as the electric field intensity reduces.
2.Classification Core losses in transformers can be categorized into hysteresis losses and eddy
current losses.
Hysteresis Losses: The transformer’s operating principle is based on electromagnetic induction,
facilitating voltage transformation and current variation. The magnetic flux flows through the
52. iron core, which presents magnetic resistance to the flux, similar to how a conductor resists
electric current. This resistance generates heat, resulting in losses known as “hysteresis losses.”
Eddy Current Losses: When the primary winding of a transformer is energized, the magnetic flux
it generates flows through the iron core. Since the iron core is also a conductor, an induced
electromotive force (emf) is generated in the plane perpendicular to the magnetic lines. This emf
forms a closed loop in the cross-section of the iron core, creating currents known as “eddy
currents.” The losses resulting from these eddy currents are termed “eddy current losses.” To
mitigate these losses, the iron core is made up of thin laminations, as thinner laminations
increase resistance and reduce current.
3.Influencing Factors
Operating Voltage and Frequency: Core losses are affected by the operating voltage and
frequency of the transformer, as these factors influence the magnetic field strength and hysteresis
phenomena in the core.
Core Material: The hysteresis characteristics of the core material significantly impact core losses.
Poor selection of core material can lead to increased hysteresis losses.
Manufacturing Process: The manufacturing process of the transformer, including the method of
lamination and insulation treatment, also affects core losses.
4.Methods to Reduce Core Losses
Select High-Quality Core Materials: Using core materials with low hysteresis losses can reduce
transformer core losses.
Optimize Manufacturing Process: Improving the lamination method and insulation treatment
during manufacturing can help lower core losses.
Rational Design: During the design phase, optimizing the structural design and selecting
appropriate parameters can reduce core losses.
By addressing these factors, the efficiency and operational lifespan of transformers can be
enhanced, thereby reducing operational costs and improving overall performance.
Comprehensive Guide to Transformer Core: Types, Materials, and Applications
1 Comment / By Shinenergy / October 31, 2024
The Transformer Core is like the “heart” of a human being. Without it, the flow of electricity
cannot proceed smoothly. In all types of transformers, the material and design of the core
determine the efficiency and quality of power transmission. A good transformer core is like a
53. highway that allows power to flow from one end to the other without hindrance. In this guide, we
will take an in-depth look at the various types of transformer core materials and their application
scenarios. Let’s start with the core elements of a transformer core and demystify it step by step to
help you find the best option.
Figure 1 transformer cores
Table of contents shinenergy
1 What is a Transformer Core?
1.1 What is the function of Transformer Core？
1.2 Benefits of Choosing the Right Transformer Core
2 Components of a Transformer Core Construction
2.1 Transformer Core Limbs VS Core Columns
2.2 Transformer Core Yoke VS Connecting Part
2.3 Materials for Transformer Core: Importance and Selection Criteria
2.4 Cold Rolled Grain Oriented Steel
2.5 Amorphous Steel
2.6 Nanocrystalline Materials
54. 3 Key Manufacturing Processes in Core Production
3.1 Cold Rolling
3.2 Annealing
3.3 Lamination
4 Core Design and Assembly Configurations
4.1 what is shell type transformer？
4.2 Core Type transformer
4.3 Shell Type Transformer vs Core Type Transformer
5 Comparing Limb Configurations in Transformer Cores
5.1 Three Limb Core
5.2 Four Limb Core
5.3 Five Limb Core
6 Types of Transformer Cores for Specialized Applications
6.1 Distributed Gap Core
6.2 Laminated Core
6.3 Amorphous Cores
6.4 Nanocrystalline Cores
7 Recommended Transformer Cores Materials for Maximum Efficiency in Various Applications
7.1 Photovoltaic (PV) Power Systems
7.2 Energy Storage Systems
7.3 Wind Energy & Hydrogen Production
7.4 Data Centers
8 Conclusion: Best Practices in Transformer Core Selection
9 FAQ
9.1 What advantages do UTC iron core transformers offer in audio processing？
9.2 what is the best transformer core material for adding color to audio?
9.3 What are the key steps in the construction of transformer cores, particularly for iron core
construction and current transformer construction?
9.4 What are transformer windings typically wrapped around, and why is this core structure
important?
9.5 What is the purpose of the transformer, and how does it support electrical systems?
9.6 What are transformers made of ?
9.7 What role do transformer windings play in their function ?
9.8 How many types of transformer are there, and what are the types of transformer based on
their function?
9.9 How to remove copper wire from transformer safely and effectively?
What is a Transformer Core?
55. Figure 1-1 Transformer core materials
What is the function of Transformer Core？
Figure 1-2 Purpose of transformer core
The transformer core acts as a “bridge” between energies. Simply put, the core is responsible for
conducting the magnetic field between the primary and secondary coils, transforming electrical
energy from one voltage to another without loss.
It is the iron core that allows the power to travel smoothly “across the bridge” to where it needs
to go, without losing too much energy due to resistance in the process. The transformer core is
made up of high-quality magnetic materials to ensure efficient energy transfer.
56. Benefits of Choosing the Right Transformer Core
Figure 1-3 transformer core losses
Choosing a high quality core is the same as equipping the transformer with a more efficient
“engine”. A high-quality iron core reduces energy loss, improves the efficiency of the
equipment, and allows more stable transmission of electricity. This not only extends the service
life of the transformer but also reduces the cost of routine maintenance, just like a high-
performance car is less prone to breakdowns, reducing the trouble of repair. In addition, the
efficient iron core can also save power, especially in the long operation of large equipment the
effect is significant, helping equipment to maintain the best performance.
Components of a Transformer Core Construction
Each part of iron core for transformer has its own role to play and works together to ensure the
smooth flow of power, like a team, without which you cannot do anything. Core type transformer
construction involves winding coils around the core limbs to create a robust magnetic circuit.
What is core made of ?Let’s take a look at these key components and their specific functions:
57. Figure 2-1 what is the material used for construction of transformer core
Transformer Core Limbs VS Core Columns
Figure 2-2 limbs meaning
58. Core Columns are like “highways” for the transmission of electricity. They are the main conduit
for magnetic flux. Magnetic fields are conducted through these core columns and electrical
energy is converted between them. The quality and structure of the core columns determines the
efficiency of the magnetic flux transfer, just like the width and quality of a highway, which
directly affects the smoothness of the traffic flow.
Transformer Core Yoke VS Connecting Part
Figure 2-3 yoke transformer
The crossbeam is connected to the ends of the core columns and acts as a “connecting hub” on
the bridge, linking each core column in series. It not only closes the magnetic circuit, but also
ensures the smooth flow of magnetic flux throughout the core. It is the presence of the crossbeam
that keeps the magnetic force circulating within the core without “spillage” or “leakage”. The
stable beam design acts as a sturdy bridge, guaranteeing the efficient flow of energy within the
core and providing the transformer with long-lasting, stable electromagnetic performance.
Materials for Transformer Core: Importance and Selection Criteria
59. Figure 3-1 what material is used for the core of a transformer
Choosing the right material is critical for transformer cores. The material determines the
magnetic permeability, energy loss and overall performance of the core. Good materials make
the core more efficient in energy transfer, just as choosing quality cable materials makes the
current flow smoother. Below are a few commonly used materials and their performance
characteristics:
Cold Rolled Grain Oriented Steel
Figure 3-2 CRGO steel
CRGO steel is like the “gold standard” for transformer cores. The material is specially oriented
to provide a significant increase in magnetic properties. The directionality of the grain structure
makes it easier for the magnetic flux to flow along specific paths, reducing hysteresis losses.
This material is particularly suitable for power transmission scenarios that require high efficiency
and low losses, and like a road surface designed for high speeds, it ensures that the magnetic flux
flows “at high speeds” through the core, thus improving the overall efficiency of the transformer.
Amorphous Steel
60. Figure 3-3 the development trends in amorphous core transformer
Amorphous steel excels in terms of no-load losses. It has a disordered structure, like
“uncrystallized glass”, and this amorphous structure allows the magnetic flux to pass through
with less resistance. Amorphous steel cores are better suited to energy-efficient transformers,
especially in situations where power is used intermittently, such as in photovoltaic systems. Its
low no-load losses mean that even in non-operating conditions, energy losses are very low, like
an energy-saving appliance in standby mode, minimizing waste.
Nanocrystalline Materials
Figure 3-4 nanocrystalline materials
Nanocrystalline materials are the “new kid on the block” in transformer cores, with extremely
high permeability and excellent thermal stability. The nano-scale grain structure allows the
material to better adapt to high-frequency electromagnetic wave conduction and reduce eddy
current losses. This characteristic makes nanocrystalline materials particularly suitable for use in
high-efficiency transformers, especially in modern applications requiring high frequency and low
loss, such as data centers and energy storage systems. It can be said that nanocrystalline
materials have brought the core into a new era of “precision technology”, supporting higher
energy efficiency in a small space.
Key Manufacturing Processes in Core Production
61. Figure 4 Manufacturing Processes in Core
The manufacturing of an efficient transformer core is not possible without a high level of
craftsmanship. Key processes not only determine the performance of the material, but also
greatly enhance the energy efficiency of the core, just as the precise temperature and time of
baking determine the texture of the pastry. The following are the three main processes commonly
used in the production of iron cores:
Cold Rolling
Figure 4-1 cold rolling process
The cold rolling process works like “precision engraving,” pressing the material thinner and
denser to improve magnetic properties. Cold rolling increases the density and strength of the core
material, significantly reducing energy losses.
This process makes the material tighter, like the pages of a hard-compacted, laminated book,
which is less likely to “leak”, thus enhancing the effect of magnetic flux conduction. Cold rolled
cores are significantly more efficient and loss resistant, making them ideally suited to the needs
of high-performance transformers. Soft iron is used as a core of transformer to enhance magnetic
flux efficiency and reduce losses.
Annealing
62. Figure 4-2 annealing process
Annealing is the process of “stretching” a material. By heating the material and then slowly
cooling it, annealing releases stresses within the material, increasing the permeability and
allowing the magnetic flux to flow more smoothly. Think of it as a deep massage for tired
muscles, where energy travels more easily through the core. Annealed cores are more stable
magnetically, reducing energy loss due to material stress and extending the life of the core. Soft
iron is used to make the core of transformer due to its excellent magnetic permeability and low
energy loss.
Lamination
Figure 4-3 lamination process
The lamination process reduces eddy currents generated by changes in the magnetic field by
dividing the transformer core lamination material into thin slices and stacking them one on top of
the other, like placing a fence in a high-speed stream of water, reducing unwanted “whirlpools”.
This layered design not only improves energy efficiency, but also reduces heat generation and
ensures that the transformer remains “cool” during long periods of operation. The application of
the lamination process makes the core more adaptable to high-efficiency, low-loss operating
environments.
63. A laminated iron core minimizes eddy current losses, enhancing transformer efficiency and
performance.
Core Design and Assembly Configurations
Figure 5 shell type transformer and core type transformer
The way the transformer laminations is designed and assembled directly determines the
operational performance of the transformer. Different configurations are adapted to different
needs, just as a bridge is designed to take into account flow and topography. There are two main
designs of transformer cores – Shell-Type and Core-Type – which are unique in their structure
and function.
64. What is shell type transformer?
Figure 5-1 shell type transformer
The shell core is like a “fortress”, the core surrounds the coil in the center, forming a stable,
closed flux circuit. This design greatly reduces magnetic leakage and ensures centralized energy
transfer. The advantage of the shell structure is that it is highly resistant to short-circuits, which
makes it suitable for high-current-demanding scenarios, such as large-scale industrial power
equipment or equipment with stringent requirements for voltage fluctuations. They act as a
strong lock, keeping the energy tightly inside and minimizing “leakage”. A core and shell type
transformer uses different structural designs to optimize magnetic flux distribution and meet
various application needs.
Core Type transformer
65. Figure 5-2 core type transformer
The core type core is relatively open, with the coil surrounding the outside of the core and the
magnetic flux being conducted throughout the core. This design is more flexible, simple and
relatively inexpensive to produce. Core constructions are better suited for applications that
require more space for heat dissipation, such as high-power power transformers. They act as an
unobstructed thoroughfare, allowing current to flow freely through the core, which facilitates
heat dissipation and reduces heat loss.
Shell Type Transformer vs Core Type Transformer
Figure 5-3 difference between shell type transformer and core type transformer
The core type and shell type transformer difference lies in their magnetic circuit design and
winding placement, impacting efficiency and application suitability.
Comparing Limb Configurations in Transformer Cores
66. Figure 6-1 Comparing Limb Configurations in Transformer Cores
The column configuration of the transformer magnetic core can be flexibly adjusted according to
power requirements and application scenarios. The design of different number of columns, like
the layout of pillars in a house structure, determines the stability and applicability of the whole
transformer. Let’s take a look at the unique advantages and typical applications of three-, four-
and five-pillar designs.
Three Limb Core
67. Figure 6-2 3 limb core transformer
The Three Limb Core is the “classic” of transformer cores. Its compact layout is suitable for
most conventional applications, especially where space is limited. The three-post design reduces
the use of core material, making the transformer simple and cost-effective. The lightweight
design serves as an “all-around compact sports car,” meeting regular power needs without taking
up too much space, and typically suits low to medium power applications, such as residential or
small commercial facilities.
Four Limb Core
Figure 6-3 4 Limb Core
The Four Limb Core adds an auxiliary post to the original three-post design to enhance the
balance of the magnetic field. This configuration allows the lamination of the transformer to
perform better with asymmetrical loads, acting as a “balance stabilizer” for more complex
current variations. This design is particularly suitable for applications where load balancing is
required to help maintain a smooth power supply, such as medium-sized industrial equipment
where continuity of supply is important.
Five Limb Core
68. Figure 6-4 5 Limb Core
The Five Limb Core is a “high-strength heavy-duty player”, and its design adds a balancing
column to the four main columns to enhance the stability and fault tolerance of the iron core.
This structure is suitable for industrial applications with very high power and high-reliability
requirements and is capable of stable operation under the most extreme load conditions.
The five-pillar design gives the transformer core greater shock resistance, functioning as a solid
bridge that withstands any current fluctuation, no matter how strong. Heavy industry, power
stations, and large infrastructure projects commonly use this design.
Types of Transformer Cores for Specialized Application
Figure 7 core type transformer diagram
Different types of cores show their own advantages in specific applications. Choosing the right
types of core based on the application scenario and energy efficiency requirements is like tailor-
made equipment that can significantly improve the overall performance of your equipment.
69. Below are a few common core types and their unique benefits. A core type transformer features
windings surrounding the core, providing efficient magnetic flux flow and improved stability.
Distributed Gap Core
Figure 7-1 distributed gap core
Distributed air-gap cores are like carefully arranged small partitions, with multiple small air gaps
spread out in the magnetic circuit to reduce concentrated “leakage” of magnetic flux. This
structure effectively reduces leakage losses and results in a more uniform energy flow, like a
diversion dam on a river, spreading the pressure of the water flow. This design is particularly
suitable for applications sensitive to energy loss, such as precision instruments and control
systems, to help maintain high efficiency in power transmission.
Nickel iron transformer vs steel highlights differences in magnetic permeability and efficiency,
with nickel iron offering lower losses at high frequencies.
Laminated Core
Figure 7-2 laminated core transformer
Stacked cores reduce eddy current losses caused by changes in the magnetic field by dividing the
core into thin sheets and stacking them one on top of the other. This structure acts as an
insulating layer of thin paper, preventing “short circuits” from occurring. The laminated design
70. in conventional transformers offers an economical and effective way to improve energy
efficiency. For low-frequency power applications or long-duration equipment, laminated iron
core transformers provide reliable performance, making them popular in power transmission and
distribution. Laminating the core with thin sheets of silicon steel reduces eddy current losses and
increases efficiency.
Amorphous Cores
Figure 7-3 amorphous core transformer
Amorphous and nanocrystalline cores are known for their high efficiency and low losses.
Amorphous cores have a disordered structure that resembles liquid solidified “glass”, which
greatly reduces no-load losses. This material is ideal for energy-efficient applications, such as
photovoltaic power generation and energy storage systems, where energy efficiency is
maintained at low loads. An amorphous core transformer provides high efficiency and reduced
energy losses due to its unique core structure.
Nanocrystalline Cores
Figure 7-4 amorphous nanocrystalline cores
71. Nanocrystalline cores excel in high-frequency applications due to their ultra-high permeability
and very low eddy current losses. It’s like a technological “energy-saving device” that is
especially suited for applications requiring high efficiency and stability, such as data centers and
high-end industrial equipment.
Technical Specifications
Characteristics of CRGO electrical steel are affected by impurities, grain size, grain orientation
and surface insulation. Even minor stresses, burrs, edge cambers or bends can increase core
losses and magnetizing current significantly. Jay Bee Laminations Limited has the facilities to
ensure proper handling and stress free processing of the material.
General physical and mechanical properties of CRGO steel
Density 7.65 g/cm3
Thickness of sheet 0.23 - 0.35 mm
Silicon content 3-4 %
Yield Point (relative to rolling
direction)
0 degrees • 330 N/mm2 90 degrees • 355 N/mm2
Tensile strength 0 degrees • 348 N/mm2 90 degrees • 412 N/mm2
Elongation 0 degrees • 11% 90 degrees • 31%
Number of bends 0 degrees • 21 90 degrees • 15
Hardness (Hv) 204
Stacking factor 95-98%
Electrical Steel
Grade
(BIS nomenclature)
Grade
(Conventional nomenclature)
Thickness
(mm)
Max Core loss
(W/kg) 50 Hz
@1.5T @1.7T
CRGO 20HP70D 20-70 0.20 0.52 0.70
23HP75D 23-75 0.23 0.55 0.75
72. Electrical Steel
Grade
(BIS nomenclature)
Grade
(Conventional nomenclature)
Thickness
(mm)
Max Core loss
(W/kg) 50 Hz
@1.5T @1.7T
23HP85D 23ZDKH 0.23 0.60 0.85
23HP90 23M0-H 0.23 0.64 0.90
23HP100 M3 (Low loss) 0.23 0.68 1.00
23CG110 M3 0.23 0.70 1.10
27HP90D 27ZDKH 0.27 0.66 0.90
27HP100 27M0-H 0.27 0.70 1.00
27HP110 M4 (Low loss) 0.27 0.78 1.10
27CG120 M4 0.27 0.85 1.20
30CG130 M5 0.30 0.90 1.30
CRNGO
35C230 0.35 2.30
50C470 0.50 4.70
50C600 0.50 6.00
Grade classification of Electrical Steel
Tolerance chart for dimensions of CRGO laminations (as per IS 3024)
Attribute Attribute Range/Value Tolerance
Width
0 - 100 mm
100 mm - 230 mm
230 mm - 400 mm
400 mm - 750 mm
+0.00 / -0.15 mm
+0.00 / -0.20 mm
+0.00 / -0.30 mm
+0.00 / -0.50 mm
73. Length
0 - 350 mm
350 mm - 1,000 mm
1,000 mm - 2,000 mm
2,000 mm - 3,000 mm
3,000 mm - 4,000 mm
+0.00 / -0.30 mm
+0.00 / -0.60 mm
+0.00 / -1.00 mm
+0.00 / -1.50 mm
+0.00 / -2.00 mm
Thickness
0.23 - 0.27 mm
0.30 - 0.35 mm
+/- 0.025 mm
+/- 0.030 mm
Mitering Angle 45 degrees +/- 5 minutes
Burr Height
0.18 - 0.23 mm
0.23 - 0.30 mm
0.30 - 0.35 mm
10 microns
15 microns
20 microns
Wave Factor
Material width > 150mm,
Flatness deviation
Max. 1.5% of width
Edge Camber Material width > 150mm
Max. 0.8 mm
for length of 1.5m
Hole Dimension Up to 34 mm +/- 0.15 mm
Figure 8-3 green hydrogen production
Wind energy hydrogen systems need cores stable under high loads. Both CRGO steel and
nanocrystalline materials reduce losses and boost durability. Nanocrystalline cores perform
better in high-frequency, fluctuating outputs, while CRGO steel provides low losses and
efficiency with load variations.
Data Centers
Figure 8-4 data center transformer
Data centers require continuous high-density power supply. The low eddy current loss of
laminated cores and the high efficiency of nanocrystalline materials enable them to stably
support sensitive loads in data centers. In addition, nanocrystalline materials help to reduce heat
accumulation and lower cooling costs, further improving data center operational efficiency.
Conclusion: Best Practices in Transformer Core Selection
Figure 9 core current transformer
74. Choosing the right transformer iron core is essential for performance and energy efficiency.
Different applications require specific core types, such as distributed air gap, laminated
structures, or energy-efficient amorphous and nanocrystalline cores. Selecting the right core
enhances efficiency, reduces operating costs, and supports long-term energy savings. For more
information or procurement needs, contact Shinenergy, dedicated to providing high-quality,
efficient transformer core solutions for diverse industries.
