Monitoring of power transformers using thermal model and permission time of overload

International Journal of Electrical and Computer Engineering (IJECE)
Vol. 12, No. 3, June 2022, pp. 2323~2334
ISSN: 2088-8708, DOI: 10.11591/ijece.v12i3.pp2323-2334  2323
Journal homepage: http://ijece.iaescore.com
Monitoring of power transformers using thermal model and
permission time of overload
Huthaifa Ahmad Al_Issa1
, Mohamed Qawaqzeh1
, Serhii Kurashkin2
, Serhii Halko2
, Serhii Kvitka2
,
Oleksandr Vovk2
, Oleksandr Miroshnyk3
1
Department of Electrical and Electronics Engineering, Faculty of Engineering, Al Balqa Applied University, Al-Salt, Jordan
2
Department of Electrical Engineering and Elmecromechanics named after Professor V.V. Ovcharov, Faculty of Energy and Computer
Technology, Dmytro Motornyi Tavria State Agrotechnological University, Melitopol, Ukraine
3
Department of Power Supply and Energy Management, Faculty of Energy, Digital and Computer Technologies, State Biotechnological
University, Kharkiv, Ukraine
Article Info ABSTRACT
Article history:
Received Apr 20, 2021
Revised Dec 19, 2021
Accepted Jan 10, 2022
This paper presents the problem of increasing the reliability of electricity
supply to consumers. Uninterrupted power supply to electricity consumers
depends on the reliability of power supply system in general and power
transformers in particular, the accident rate of which is quite high. The causes
of the problem are the location of transformer substations at a considerable
distance from the service centers, their spreading out over a large area, missing
information about the current modes of their operation and so on. One of the
ways to solve this problem is development and implementation a system for
continuous diagnostics of power transformers. Failure analysis of power
transformer based on fault tree is considered, the diagnostic parameters are
determined. The insulation wear rate and permission operating time under
overload have been defined with help of equivalent heat circuit. It is proposed
to use a permission time as a parameter to diagnose the operation mode and
increase the efficiency of maintenance of substations through remote
monitoring based on the global service mobile (GSM) network. Remote
diagnostics allows to receive an information about emergency situation
timely. It helps to reduce operating costs, to ensure the reliability and quality
of electricity supply for consumers.
Keywords:
Condition monitoring
GSM
Power transformer
Remote monitoring
Substation protection
This is an open access article under the CC BY-SA license.
Corresponding Author:
Huthaifa Ahmad Al_Issa
Department of Electrical and Electronics Engineering, Faculty of Engineering, Al Balqa Applied University
Al-Salt, Jordan
Email: h.alissa@bau.edu.jo
1. INTRODUCTION
Power transformers are required components in the transmission and distribution network of
electricity delivery on the reliability of which depends the quality of electricity supply to consumers. The failure
of even a single transformer can lead to significant economic losses and poor maintenance of dozens of energy
facilities. The reliability of power transformer is largely determined by the reliability of its winding [1], [2],
which depends on the insulation condition. The aging of insulation is influenced by various operational factors,
but current overload played the main role when thermal wear is accelerated. Overload leads to local insulation
defects of winding and then complete short circuit and power transformer failure. In addition to current
overload, the power transformer is affected by other factors as shown in Figure 1. One of them is the ambient
temperature, which has significant fluctuations both during a day and season. Rising an ambient temperature
directly causes overheating of insulation resulting in intense wear [3].

 ISSN: 2088-8708
Int J Elec & Comp Eng, Vol. 12, No. 3, June 2022: 2323-2334
2324
Figure 1. Transformer failure tree
Ambient humidity affects the insulating properties of transformer oil, accumulation of oxygen and
sediment in the oil and on the active parts of the transformer, reducing the mechanical strength of insulation
and raises its wear. The load of the power transformer depends on many factors–seasonality of work, number
and type of consumers. Incomplete design of electrical networks, lack of automation and control over the load
of powerful electricity consumers also affect overloads. Starting currents of powerful electric motors, short
circuits and switching overvoltages in distribution networks have dangerous operational influence on isolation
of the transformer. Systematic overloads are the cause of untimely insulation aging and transformers failure.
Cooling conditions deterioration of the insulating structure occurs due to leakage of transformer oil, insufficient
natural ventilation [4].
Factors mentioned above affects both individually and collectively on insulating structure reliability
of the transformer winding–the most vulnerable element of its structure. Although transformers are considered
to be very reliable equipment, the current fleet of them is quite old. The average age of transformers operated
in distribution networks is 30 years, in utilities–20 years, in industry–15 years [5] that is, the service life of a
significant part of the operating transformers has a limit value or close to it. Most of these transformers are
installed at 10/0.4 kV consumer transformer substations and are under specific operating conditions
asymmetrical load, seasonal load schedule, ambient temperature fluctuations, long transmission power lines.
This, in combination with the significant ageing of transformers, leads to the fact that over the years the number
of transformers failures increases as shown in Figure 2.
Figure 2. Development of the transformer failure rate in three different applications

Int J Elec & Comp Eng ISSN: 2088-8708 
Monitoring of power transformers using thermal model and permission time … (Huthaifa Ahmad Al_Issa)
2325
A similar problem of increasing the continuity and quality of power supply exists in the European
Union (EU) countries, where up to 8-10% of transformer substations fail annually [6]. Unexpected fails of
power transformers cause serious limits in the operation of distribution networks. It leads to unscheduled power
outages and problems for electricity delivery to consumers–this affects the economic performance and
reputation of both energy supply companies and their customers. The significant cost of power transformers
and their repair should also be taken into account [7]. The above shows that at present there is a problem of
improving the operational reliability of power transformers installed in consumer substations.
The main reasons of power transformers failure are short circuits in electrical grid, overload,
atmospheric overvoltages, reduced quality of transformer oil during operation, deterioration of cooling
conditions, asymmetry with load currents [6]. In addition, the untimely and insufficient maintenance of power
transformers and shortage of reliable information about the current modes of their operation contribute to the
unsolved problem. This is especially true for that part of the power supply system where transformer
substations are spreaded out over a large area and a considerable distance from service centers [8].
One of the ways to increase the reliability of power transformers is the development and
implementation of remote diagnostics of their modes (remote monitoring). It allows to inform the emergency
situation timely, which reduces operating costs, ensures the reliability and quality of electricity supply to
consumers. First of all, remote diagnostics is actual for transformers without permanent maintenance. It leads
to a significant reduction of transformer failures–according to According to international council on large
electric systems (CIGRE) the probability of failures is reduced by 2.5 times. Early detection of problems can
reduce repair costs by 75% and loss of revenue by 60% [9].
Remote monitoring can be done in different ways. ABB uses the transformer electronic control (TEC)
monitoring system that receives all the relevant information from just a few multipurpose sensors [10]. Data
exchange is carried out through the ethernet or internet. A feature of TEC is its focus on industrial electricity
consumers, powerful transformers. But this way is not an optimal solution for consumer power substation.
Power transformer monitoring system, which is presented in [11], provides access to a wireless fidelity
(Wi-Fi) network that has a short range (up to 50 m from the access point) and in remote locations, the
installation of power equipment is not an appropriate solution.
Some of diagnostics systems are using supervisory control and data acquisition (SCADA) technology
with power line communication (PLC) protocol to remote monitoring of power transformers [12], [13]. It is
characterized by low operation costs, but it is sensitive to the quality of the electrical network and the
interference generated by low-quality consumer equipment. The maximum range of PLC communication is
only 400 meters, which also prevents it from being used for transformers of consumer substations dispersed
over a large area.
It is noteworthy the technology for collecting and processing data from distributed wireless sensors
low-power, wide area networking (LoRaWAN) [14], [15], which has a long range. A LoRaWAN network in
rural and semi-rural areas that are partially covered by vegetation, has a range of more than 20 km [16].
Communication between sensors and a base station (gateway) that transmits data to the server or internet occurs
over the air at the frequency 433 MHz or frequency band 864-865 and 868,7-869,2 MHz. However, this
technology is still not widespread due to the insufficient number of base stations–the end user needs to provide
a full set of expensive equipment.
According to discussed above, it follows that many power transformer remote diagnostics systems
use data transmission channels that are limited by distance. The most rational is the use of remote control based
on advanced wireless global service mobile (GSM) technology [17]. Base stations of various mobile operators
cover most of the territory near settlements, which allows using relatively inexpensive available equipment for
remote diagnostics and monitoring of power transformers.
The usage of GSM network for remote monitoring of power transformers is not new, several studies
[18]–[22] have previously paid attention to this issue. GSM network technology is used in the online
environmental monitoring systems [23], [24] as well. The use of a GSM modem to remote monitoring the
operation of a power transformer does not require saving its power consumption [25]. The industry produces
GSM-controllers and loggers for remote control of power equipment [26], [27] but such devices are only a way
of data transmission and does not take into account the thermal processes occurring in the power transformer.
The analysis of the above developments shows that most of them apply current and temperature
sensors, but do not take into account the thermal properties of the power transformer. For example, the heating
times of a temperature sensor and a complex object such as a power transformer are different, and the oil
temperature varies depending on where the temperature sensor is installed. Thus, it is impractical not to take
into account the thermal model of the power transformer during its monitoring. In contrast to the existing
remote monitoring, we propose to construct the operation of the diagnostic device on the basis of such a
diagnostic parameter as the permission operating time under overload. This will allow the overload
characteristics of the transformer under variable load conditions to be fully taken into account. The use of such
a device will increase the operational reliability of the power transformer and ensure uninterrupted power

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supply to consumers in case of permissible overloads and enable the transformer to be disconnected in case of
emergency. The following is required for the design of this device: i) to analyze the equivalent heat circuit and
system of thermal balance equations, ii) to obtain a mathematical model of the functional state of a power
transformer based on its thermal model, iii) to verify the adequacy of the obtained mathematical model
experimentally, and iv) to make an algorithm of the remote diagnostic device, in which the GSM-module
transmits information about the current state of the transformer.
2. RESEARCH METHOD
To develop a system for power transformer remote diagnostics it is necessary to consider a model of
its functional state, which means the transformer ability to transmit electrical energy. Power transformer has a
rated (nominal) functional state when transmitting electricity, a wear rate of the transformer resource is nominal
or less. When transmitting electricity, a wear rate of insulation resource is greater than nominal value the
transformer has a non-nominal functional state. The wear rate of transformer resource ε is determined mainly
by the consumption rate of isolation resource. It depends mainly on thermal wear of the insulation, and is
determined by the (1) [28]:
𝜀 = 𝜀𝑛exp (𝐵 (
1
𝜃𝑛
−
1
𝜃
)) (1)
where εn is nominal wear rate of isolation resource; В is a temperature coefficient characterizing the insulation
class (K); θn is a nominal absolute insulation temperature (K); θ is a current absolute insulation temperature
(K),
𝜃 = 𝜏1 + 𝑒𝑛𝑣 + 273 (2)
where 1 is an exceeding the insulation temperature of winding above the ambient temperature (ºC) and ϑenv is
an ambient temperature (ºC). Exceeding the insulation temperature 1 depends on many factors, but the main
one is the current load. To establish the relationship between exceeding insulation temperature and current of
the transformer, there should be considered how the heating process of power transformer runs during
symmetrical overload. According to equivalent heat circuit [29], [30] the power transformer thermal model is
presented as a system of three bodies – winding, magnetic circuit (core) and oil as shown in Figure 3.
Figure 3. The equivalent heat circuit-based thermal model of power transformer
Bodies 1, 2, 3 (winding, core and oil) have their own heat capacity С1, С2, С3 and interconnected by
thermal conductivity 12, 13, 23. Body 3 is linked to the environment by thermal conductivity. Environment
heat capacity Сenv is equal to infinity. Bodies release heat through active power losses Р1, Р2, Р3. It is assumed
that no dependence between heat capacity and thermal conductivity from temperature. The ambient
temperature env is constant. The system of differential equations of heat balance for the above circuit is as (3):
С1𝑑𝜏1 + 𝛬12(𝜏1 − 𝜏2)𝑑𝑡 + 𝛬13(𝜏1 − 𝜏3)𝑑𝑡 = 𝑃1(1 + 𝛼𝜏1)𝑑𝑡
С2𝜏2 + 𝛬23(𝜏2 − 𝜏3)𝑑𝑡 − 𝛬12(𝜏1 − 𝜏2)𝑑𝑡 = 𝑃2𝑑𝑡
С3𝜏3 + 𝛬𝜏3𝑑𝑡 − 𝛬13(𝜏1 − 𝜏3)𝑑𝑡 − 𝛬23(𝜏2 − 𝜏3)𝑑𝑡 = 𝑃3𝑑𝑡
} (3)
where 1, 2, 3 is temperatures rise above the ambient temperature of corresponding body (ºC); С1d1, С2d2,
С3d3 is energy used to heat up the corresponding body (J); Р1dt, Р2dt, Р3dt is energy released as heat in
corresponding body (J); 12(1–2)dt is energy transfer from winding to magnetic core (J); 13(1–3)dt is

2327
energy transfer from winding to oil (J); 23(2 –3)dt is energy transfer from magnetic core to oil (J); 3dt is
thermal energy transfer from oil to ambient environment (J) and  is temperature coefficient of resistance for
conductor material (1/ºC). The system of (3) solution using classical method [9], [10] does not take into account
the magnetic circuit and oil influence on transformer winding heating, so this system has been solved by
differential operator method. Taking into account the overcurrent ratio k, the system of (3) according to this
method is (4):
(рС1 + 𝛬12 + 𝛬13 − 𝛼𝑘2
Р1н)𝜏1 − 𝛬12𝜏2 − 𝛬13𝜏3 = 𝑘2
Р1н/𝑝
−𝛬12𝜏1 + (рС2 + 𝛬12 + 𝛬23)𝜏2 − 𝛬23𝜏3 = 𝑘2
Р2н/𝑝
−𝛬13𝜏1 − 𝛬23𝜏2 + (рС3 + 𝛬 + 𝛬13 + 𝛬23)𝜏3 = Р3/𝑝
} (4)
where p is a differential operator; P1n, P2n is power of corresponding body under nominal rate (W). The solution
to system of (4) after simplification is winding temperature excess:
𝜏1(р) =
𝛥1(р)
𝛥(р)
=
р2𝑏1+р𝑐1+𝑑1
𝑝(р3𝑎+р2𝑏+р𝑐+𝑑)
(5)
Coefficients of the equation are:
a=C1C2C3;
b=C1C2(Λ+Λ13+Λ23)+C1C3(Λ12+Λ23)+C2C3(Λ12+Λ13–αk2
P1n);
c=Λ12(C1+C2)(Λ+Λ13+Λ23)+C1Λ23(Λ+Λ13)+C2Λ13(Λ++Λ23)+C3(Λ13Λ12+Λ13Λ23+Λ12Λ23)–
αk2
P1n(C2Λ13+C2Λ23+C3Λ12+C3Λ23+C2Λ);
d=Λ12Λ23Λ+Λ12Λ13Λ+Λ13Λ23Λ–αk2
P1n(Λ12Λ+Λ12Λ13+Λ12Λ23+Λ23Λ+Λ13Λ23);
b1=C2C3k2
P1n;
c1=C2k2
P1n(Λ+Λ13+Λ23)+C3k2
P1n(Λ12+Λ23)+C3k2
P2nΛ12+C2P3Λ13;
d1=Λ12k2
(P1n+P2n)(Λ+Λ13+Λ23)+k2
P1nΛ23(Λ+Λ13)+k2
P2nΛ13Λ23+P3(Λ13Λ12+Λ13Λ23+Λ12Λ23)
According to Laplace transform
𝐹1(𝑝) = 𝑝2
𝑏1 + 𝑝𝑐1 + 𝑑1 (6)
𝐹2(𝑝) = 𝑝3
𝑎 + 𝑝2
𝑏 + 𝑝𝑐 + 𝑑 (7)
The (5) will take the form
𝜏1(𝑝) =
𝐹1(𝑝)
(𝑝𝐹2(𝑝))
(8)
The equation 1(t) is original function of image (7):
𝜏1(𝑝) =
𝐹1(0)
𝐹2(0)
+
𝐹1(𝑝1)
𝑝1𝐹2
′ (𝑝1)
𝑒𝑝1𝑡
+
𝐹1(𝑝2)
𝑝2𝐹2
′ (𝑝2)
𝑒𝑝2𝑡
+
𝐹1(𝑝3)
𝑝3𝐹2
′ (𝑝3)
𝑒𝑝3𝑡
(9)
   
 
t
p
t
p
t
p
e
c
bp
ap
p
d
p
c
p
b
e
c
bp
ap
p
d
p
c
p
b
e
c
bp
ap
p
d
p
c
p
b
d
d
3
3
2
3
3
1
3
1
2
3
1
2
2
2
2
2
1
2
1
2
2
1
1
1
2
1
1
1
1
1
2
1
1
1
1
2
3
2
3
2
3


















(10)
where p1, p2, p3 are roots of the (7). Relation (10) is the heating equation of power transformer winding as a
time function of thermal model that consist of three bodies (winding, magnetic circuit and oil). In contrast to
the classical transformer thermal model, in mathematical heating model obtained, each body affects the heating
of another body, including the winding, and part of this influence varies exponentially. A heating curve of the
transformer winding is the sum of three exponents. Each body effects on that heating. Non-variable component
F1(0)/F2(0) shows from which state (cold or heated) the transformer is loaded.
The temperature exceeding of transformer winding 1(t) depends on the constant design parameters
(heat capacity of the active parts and thermal conductivity between them), as well as on the variable parameters
(active energy losses in the bodies). The last depends on the overcurrent ratio k. Thus, it follows from (9), (10)
that heating equation of transformer winding as a heterogeneous system has the form:

 ISSN: 2088-8708
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𝜏1 = 𝜏1𝑠𝑡𝑎𝑏
′
(1 − 𝑒−𝑡/𝑇′
) + 𝜏1𝑠𝑡𝑎𝑏
′′
(1 − 𝑒−𝑡/𝑇′′
) + 𝜏1𝑠𝑡𝑎𝑏
′′′
(1 − 𝑒−𝑡/𝑇′′′
) (11)
where '1stab, ''1stab, '''1stab are established partial exceedances of the winding temperature (ºC) and Т', Т'', Т'''
are partial time constants of heating winding (s).
𝑇′
= −1/𝑝1; 𝑇″
= −1/𝑝2; 𝑇‴
= −1/𝑝3 (12)
According to research of TM-25/10 power transformer, the thermal model partial components that
have a larger time constant (Т) determine the duration of the thermal process, while the components with
smaller ones (Т'', Т''') affect only the initial stage of heating as shown in Figure 4. The heating curve of power
transformer represented by a homogeneous body is differs from curve of heterogeneous system. As seen in
Figure 5 there is a divergence up to 30% at the beginning of heating, which over time almost disappears. If
replace the real heating curve of transformer winding with an equivalent one, it could be obtained the heating
equation:
𝜏1 = 𝜏1𝑠𝑡𝑎𝑏(1 − 𝑒−𝑡/𝑇
) + 𝜏1𝑠𝑒−𝑡/𝑇
(13)
where 1stab is established and 1s is initial temperatures excess winding temperature (ºC); t is a current time (s)
and Т is equivalent heating constant (s):
n
n
n
n
Р
т
С
т
С
т
С
Т



 3
3
3
2
2
2
1
1
1 


(14)
where m1, m2, m3 are the winding, core and oil masses accordingly (kg); τ1n, τ2n, τ3n are the winding, core and
oil excess temperatures in nominal mode accordingly (ºC), ΔPn is power loss in the transformer in nominal
(W).
Figure 4. Partial components1, 1, 1 of heating
curve
Figure 5. Heating curves 1(t) of heterogeneous (1)
and homogeneous (2) power transformer model
The established temperature of winding is calculated as (15):
𝜏1𝑠𝑡𝑎𝑏 = 𝜏1𝑛
𝑎+𝑘2
𝑎+1−𝛼𝜏1𝑛(𝑘2−1)
(15)
where a is a relation of power loss in the core ΔРconst.n to power loss in the winding ΔРvar.n under rated load and
k is an overcurrent ratio
𝑘 = 𝐼/𝐼𝑛 (16)
where I is an effective value of the overload current (A) and In is a rated (nominal) value of the current (A).
When overload current increases, the permission operating time tp decreases. During this time the
winding temperature reaches the limit value. If to set a certain exceeding temperature limit for winding τp, it

2329
could be found the permission operating time under overload. On condition 1=τp, t=tp, 1s=0 the (13) will
change to:
𝜏𝑝 = 𝜏1𝑠𝑡𝑎𝑏(1 − е−𝑡𝑝/𝑇
) (17)
The permission operating time during transformer overload is calculated as (18):
𝑡𝑝 = Т 𝑙𝑛
𝜏1𝑠𝑡𝑎𝑏
𝜏1𝑠𝑡𝑎𝑏−𝜏𝑝
(18)
Finally, (1), (2), (14), (15), (16), and (18) obtained above represent a mathematical model of the functional
state of the power transformer, based on its thermal model.
3. RESULTS AND DISCUSSION
By using the functional state model, graphs of transformer winding TM-25/10 excess temperature
τ1 = f(t) under symmetrical overload from 20 to 60 percent relative to the rated mode of operation were received
as shown in Figure 6. The obtained dependences allowed to build the overload characteristic in Figure 6 and
to estimate the overload effect on power transformer permission operation time during the winding temperature
reaches τp. It could be concluded from Figure 7 that time depends on overcurrent ratio k and decreases if it
increases.
Figure 6. Graphics of excess temperature τ1 = f(t)
Figure 7. Permission operation time tр dependence on overcurrent ratio k experiment (1) and computation (2)
results

 ISSN: 2088-8708
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To validate received model the experimental verification was provided with loading of power
transformer TM-25/10. The research was conducted in the conditions of the repair service. To obtain reliable
information, the measurements were repeated three times. As a result, the overload curve was obtained. By
using the functional state model in Figure 6, the overload curve was calculated as well. Experimental (1) and
calculated (2) overload curves comparison of power transformer in Figure 7 shows that maximum discrepancy
between analytical and experimental data does not exceed 8%. It indicates the adequacy of obtained functional
state model of power transformer.
According to research, the thermal wear rate dependences of insulation on overcurrent ratio ε = f(k)
and ambient temperature env are obtained as shown in Figure 8. Based on the obtained results, it can be
concluded that thermal wear rate of the transformer insulation depends on its design parameters and
significantly depends on the ambient temperature, the overcurrent ratio and initial preceding conditions.
According to received model of the functional state of the power transformer, the data flow diagram for the
remote diagnostics device was developed. It is presented in Figure 9.
Figure 8. Thermal wear rate ε dependences of insulation on overcurrent ratio k and ambient temperatureenv
Figure 9. Data flow diagram of power transformer diagnostics
According to diagram, the values have to be set: nominal power losses ΔРconst.n (in the core), ΔРvar.n
(in the winding) and ΔPn (in the transformer); nominal temperatures τ1n (winding), τ2n (core) and τ3n (oil); heat
capacity С1 (winding), С2 (core) and С3 (oil); nominal absolute insulation temperature θn; temperature

2331
coefficient В, value of rated current In, exceeding temperature limit for winding τp. The values of effective
current I and ambient temperature υenv are measuring by sensors. Then the device calculates by a given program
an overcurrent ratio k, equivalent heating constant Т, temperature rise of winding 1, absolute insulation
temperature θ, permission operating time tp, wear rate of transformer resource ε. The remote monitoring device
periodically informs the operator about the current status of the transformer–whether it is overloaded (ε>1) or
not (ε≤1). In case of exceeding the permission overload time, the transformer is switched off. The above
algorithm is realized in the remote diagnostic device, a block diagram of which is shown in Figure 10. The
device consists of blocks: current sensor (CS), environment temperature sensor (TS), oil level sensor (OLS),
oil temperature sensor (OTS), programming microcontroller unit (MCU) with build in ADC convertor, GSM-
module, SIM card slot, relay module (REL1-REL3), power supply (AC/DC), antenna (ANT).
The device works as follows. The current sensor measures the root mean square current value of the
power transformer, at the same time ambient temperature and oil level in the transformer tank are measured.
The microcontroller MCU calculates the overcurrent ratio k according to data received from sensors CS and
TS. In case the transformer overload exceeds the rated value, the permission operating time during overload is
calculated tp. If value tp is less than time that has elapsed since the overload occurred, a signal to disconnect
the transformer from network is generated using relay module REL.
The oil level control in the tank is performed according to a separate subprogram-the signal for
shutdown is formed only if the level falls below the critical value. The flowchart for remote diagnostic device
is shown in Figure 11 and construction is shown in Figure 12. At software intervals, the device transmits the
measured and calculated data by installed SIM card by means of the GSM-module. It is reasonable to place a
large amount of received data on a third-party WEB-server. Thus, the available database can be further used in
SCADA-system design, providing full operator control over the process.
Figure 10. Block diagram of the remote diagnostic device
Figure 11. Monitoring flowchart

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Data is transmitted to the operator with a delay typical for the GSM network-no worse than
300-1000 ms (legacy 2G networks), but usually 100-500 ms (3G networks) and even less than 100 ms
(4G networks) [31], [32]. This is normal, considering that the power transformer shutdown instantly when the
permissible overload time is reached. In contrast to similar works, the proposed method calculates the
permission operating time based on received data (oil temperature, load current) in addition to transmitting the
current data of transformer state. The outage is not immediate in the event of an abnormal situation, but after a
time sufficient to ensure that the resource flow rate does not exceed the permissible value.
Figure 12. Remote diagnostic device construction
4. CONCLUSION
The power transformer reliability depends on timely and high-quality diagnostics of thermal processes
that occur during overload. To do this, it is proposed to use a model to diagnostics the thermal mode of the
transformer. It represented by a system of three bodies-winding, magnetic circuit and oil. The result of
calculations is allowable operating time determination when power transformer under overload. Since the
transformers of distribution networks 10/0.4 kV are located on a large area away from the service organizations,
the remote monitoring usage of functional state reduces operating costs, ensures the reliability and quality of
electricity supply to consumers. It is rational to perform this control on GSM network basis, which have a
significant coverage area and range. The data obtained from remote diagnostic devices on power transformers
16-160 kVA functional state can be used to organize SCADA systems for centralized territorial maintenance
of the distribution network.
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BIOGRAPHY OF AUTHORS
Huthaifa Ahmad Al_Issa received his Bachelor’s and Master’s degrees in
Electrical and Computer Engineering at the Near East University, Cyprus, in 2003 and 2005,
respectively with high honors GPA. He received his Ph.D. degree in Electrical Engineering at
the University of Dayton, Dayton, Ohio, USA, in 2012. Currently, he is an Assistant Professor
in the Department of Electrical and Electronics Engineering at Al Balqa Applied University.
He has been a member of the Jordan Engineers Association (JEA) since 2003. He can be
contacted at email: h.alissa@bau.edu.jo.
Mohamed Zaidan Qawaqzeh graduated from The Eastern Ukrainian State
University in 2001 and was qualified as an Electrical Engineer. He received his PhD in
Electric Engineering from Donetsk National Technical University in 2006. Currently, he is an
Asssistant Professor at Al Balqa Applied University, Jordan. His research interests are in the
area of power engineering, automation system, electric drive, Smart Grid, Renewable energy.
He can be contacted at email: qawaqzeh@bau.edu.jo.

 ISSN: 2088-8708
2334
Serhii Kurashkin received the PhD degree in electrical complexes and systems
from the Tavria State Agrotechnological University, Melitopol, Ukraine, in 2011. He is the
author of two books, more than 50 articles, and 9 inventions. Currently, he is an Assistant
Professor in the Electrical Engineering and Electromechanics Department at Dmytro
Motornyi Tavria State Agrotechnological University, Melitopol, Ukraine. His research
interests include renewable energy, quality of electrical energy, losses of electrical energy,
remote monitoring and control of electrified objects. He can be contacted at email:
serhii.kurashkin@tsatu.edu.ua.
Serhii Halko graduated from Melitopol Institute of Mechanical Engineers of
Agriculture, Ukraine, in 1994, and was qualified as an Electrical Engineer. He received his
PhD in Electric Engineering (power stations, systems and networks) from the Donetsk
National Technical University, Ukraine, in 2003. Presently, he is an Assistant Professor of
Dmytro Motornyi Tavria State Agrotechnological University and Educational Scientific
Institute of General University Training, Melitopol, Ukraine. He is the author of more than
100 scientific publications, 10 inventions, and two monographs. His research interests are
related to research in the field of renewable and alternative energy. He can be contacted at
email: serhii.halko@tsatu.edu.ua.
Serhii Kvitka received the PhD degree in application of electrical technologies
in agricultural production from the Tavria State Agrotechnical Academy, Melitopol, Ukraine,
in 2003. Presently, he is a Head of Electrical Engineering and Electromechanics Department
at Dmytro Motornyi Tavria State Agrotechnological University, member of two scientific
publications editorial board. He is the author of 7 books and monographs, more than 100
articles and more than 10 inventions. His research interests include the control and protection
of power electrical equipment, microcontrollers, automation system, and control systems for
induction motors drives. He can be contacted at email: sergii.kvitka@tsatu.edu.ua.
Oleksandr Vovk graduated from Tavria State Agrotechnical Academy, Ukraine,
in 1996, and was qualified as an Electrical Engineer. The PhD degree have been received in
in Electric Engineering (power stations, systems and networks) from Tavria State
Agrotechnical Academy, Melitopol, Ukraine, in 2003. Currently, he is an Assistant Professor
of Dmytro Motornyi Tavria State Agrotechnological University. He is the author of three
books, more than 50 articles and 7 inventions. His research interests are in the area of power
engineering, energy saving in electromechanical systems. He can be contacted at email:
oleksandr.vovk@tsatu.edu.ua.
Oleksandr Miroshnyk received the M.Sc. degree from the Kharkiv State
Technical University of Agriculture, Kharkiv, Ukraine, in 2004, and the Doctor of Technical
Sciences degree from the National Technical University "Kharkiv Politechnic Institute",
Kharkiv, Ukraine, in 2016, all in electrical power engineering. He is the author of three books,
more than 200 articles, and more than 30 inventions. His research interests include the Smart
Grid, renewable energy, quality of electrical energy, losses of electrical energy, overhead
power lines monitoring, power system automation. He can be contacted at email:
omiroshnyk@ukr.net.

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