Physics Investigatory Project on transformers. Class 12th
- 1. * PHYSICS INVETIGATORY * PROJECT TRANSFORMERS Submitted by- Pratikshya Moharana Class- XII ‘A’ Roll No.- 16
- 3. Acknowledgement In the accomplishment of this project successfully, many people have bestowed their blessings upon me and given their precious time and support, I’m utilizing my thanks to all the people concerned with this project Primarily I would thank our physics teacher Mr. Sanjaya Kumar Parida, whose valuable guidance has been the one that has helped me patch this project and make it a full proof success. His suggetions and instructions have served as the major contributor towards the completionof the project. I would like to thank my parents and friends who have helped me with suggetions and advisory comments to enhance an rectify mistakes done in this project. Last but not not he least, a heartful thanks goes to my classmates whose assistance are of a huge success in the completion of this project.
- 6. Transformer is a device used for in the power transmission of electric energy. The transmission current is AC. It is commonly used to increase or decrease the supply voltage without a change in the frequency of AC between circuits. The transformer works on the basic principles of electromagnetic induction and mutual induction. Types of Transformers- Transformers are used in various fields like power generation grid, distribution sector, transmission and electric energy consumption. There are various types of transformers which are classified based on the following factors: o Working voltage range o The medium used in the core o Winding arrangement o Installation location Step-up Transformer: used between the power generator and the power grid. The secondary output voltage is higher than the input voltage. Step-down Transformer: These transformers are used to convert high-voltage primary supply to low-voltage secondary output. Air Core Transformer: The flux linkage between primary and secondary winding is through the air. The coil or windings wound on the non- magnetic strip. Iron Core Transformer: Windings are wound on multiple iron plates stacked together, which provides a perfect linkage path to generate flux. Autotransformer: It will have only one winding wound over a laminated core. The primary and secondary share the same coil. Auto means “self” in the Greek language. Power Transformer: It is used at power generation stations, as they are suitable for high voltage application Distribution Transformer: It is mostly used at distribution lanes for domestic purposes. They are designed for carrying low voltages. It is very easy to install and characterized by low magnetic losses. Measurement Transformers: They are mainly used for measuring voltage, current and power. Protection Transformers: They are used for component protection purposes. In circuits, some components must be protected from voltage fluctuation, etc. Protection transformers ensure component protection. 1. In voltage regulators for T.V, refridgerators , computers, air conditioners, etc. 2. A step- down transformer is used for welding purposes & obtaining large current 3. A step- up transformer is used for production of X- rays and neon advertisement. 4. Used in voltage regulators & stabilized power supplies. 5. Transmission of A.c currnet over long distances. Uses of Transformers
- 8. Theory Principle: a transformer works on the principle of mutual induction Principles of mutual induction: Faraday’s Law of Electromagnetic Induction: Changing magnetic fields generate an EMF in a conductor. Mutual inductance: When two coils are close together, the magnetic field from one links with the other, inducing a voltage in the second coil. Mutual inductance modifies current and voltage in a secondary coil Construction: A transformer essentially consists of 2 coils of insulated copper wire having different no. of turns and wound on the same soft iron core. The coil P to which electric energy is supplied is called the primary coil and the coil from which energy is drawn or output is obtained is called the secondary coil. When an alternating E.M.F is supplied to the primary coil P1 P2, an alternating current starts falling in it. The alternating current in the primary produces a changing magnetic flux linked with primary is also linked with the secondary is equal to that induced in each turn of the primary. Thus if Ep & Es be the instantaneous values of the E.M.F’s induces in the primary and secondary and Np & Ns are the no. of turns of the primary secondary coils of the transformer and ⅆϕ ⅆt = 𝑟𝑎𝑡𝑒 𝑜𝑓 𝑐ℎ𝑎𝑛𝑔𝑒 𝑜𝑓 𝑓𝑙𝑢𝑥 𝑖𝑛 𝑒𝑎𝑐ℎ 𝑡𝑢𝑟𝑛 𝑜𝑓 𝑡ℎ𝑒 𝑐𝑜𝑖𝑙 At this instant we have, EP = −Np ⅆϕ ⅆt …(1) And 𝐸𝑠 = −𝑁𝑠 ⅆ𝜙 ⅆ𝑡 …(2) Since the above relations are true at every instant, so by dividing (2) by (1), we get Es EP = − Ns Np …(3) As Ep is the instantaneous value of back E.M.F induced in the primary coil P1, so the instantaneous current in primary coil is due to the difference (E – Ep) in the instantaneous values of the applied & back E.M.F further if Rp is the resistance O, P1, P2 coil then the Instantaneous current Ip in the primary coil is given by, Ip = E − EP Rp E − Ep = IpRp when the resistance of the primary is small, Rp, Ip can be further neglected. Therefore, E − Ep = 0 E𝑝 = E (Thus back E.M.F = Input E.M.F) - For ideal transformers Es EP = Es E = 𝑂𝑢𝑡𝑝𝑢𝑡 𝐸.𝑀.𝐹 Input E.M.F = Ns Np = 𝐾 Es EP = Is Ip = Ns Np = Transformation Ratio
- 9. Efficiency Efficiency of a transformer is defined as the ratio of output power to the input power. η = Output power Input power = EsIs EpIp Thus in an ideal transformer where there’s no power loss, 𝐴𝑠 η = 1, But in actual practice there are many power losses η = Output power Input power x 100 Step- Up Transformer The formula is used to design a step up transformer is- 𝑵𝒔 𝑵𝒑 = 𝒗𝒔 𝒗𝒑 Where, Ns = no. of secondary turn Np = no. of primary turn Vs = voltage in secondary turn Vp = voltage in primary turn the number of turns in the secondary coils should be always greater than the number of turns in the primary coil. Np < Ns to work transformer as step- up transformers As the number of turns will be greater in secondary coil, so total E.M.F is more & hence the output voltage in secondary coil will be more than primary input voltage. Step- Down Transformer The formula is used to design a step up transformer is- 𝑵𝒔 𝑵𝒑 = 𝒗𝒔 𝒗𝒑 Where, Ns = no. of secondary turn Np = no. of primary turn Vs = voltage in secondary turn Vp = voltage in primary turn the number of turns in the secondary coils should be always less than the number of turns in the primary coil. Np > Ns to work transformer as step- down transformers As the number of turns will be less in secondary coil, so total E.M.F is less & hence the output voltage in secondary coil will be less than primary input voltage. (Ns > Np) (Ns < Np)
- 10. Flux leakage – due to air gap in the core the amount of magnetic flux linked with the secondary is less than that of primary as the energy is last. It can be reduced by winding the primary and secondary coil over one another. Inspite of best insulaters, therefore, rate of cahnge of magnetic flux linked with each turn of S1 S2 is less than the rate of change in magnetic flux linked with each turn of P1 P2 Copper loss - energy is loss in the form of heat in the copper coils of the transformer. This is due to joule heating of conducting wires. Iron loss - energy loss in the form of heat in the iron core of the transformer. This is due to formation of eddy currents in iron core. It is minimized by taking laminated cores. Hysteresis loss – loss of energydur to repeated magnetization and de- magnetization of the iron core when A.C. is fed to it. Magneto striation – humming noise of a transformer. ENERGY LOSSES
- 11. Soft iron rod (length- 15cm diameter- 1.3 cm) Enamelled copper wire (20 or 22 SWG) Enamelled copper wire (16 or 18 SWG) Step- down transformer having tappings 3, 6, 9 and 12 ac volts 2 ac voltmeters (0 - 10 volts) Thick sheet of paper
- 12. Procedure 1. Take a soft iron rod of length 15 cm & diameter 1.3 cm wrap a thick sheet of paper on it. 2. Wind 200 turns of a coil P of enamellled copper wire of 20 or 22 SWG. 3. Wind 50 turns of another coil of S enamelled copper wire of 16 or 18 SWG. 4. Both coils are wound over same length of rod, so that almost the entire flux produceed by the current in coil P is linked to the coil S. 5. Connect a step- down transformer (having tappings of 3,6,9 & 12 ac volts) & an ac voltmeter (0 – 10 V) across the ends of the coil P, as shown in the Fig. 6. Connect an ac voltmeter (0 – 10 V) across the ends of the coil S. 7. Connect the step- down transformer to the ac mains of 220 V. From it, supply 3 V to the coil P. Note the readings in both the ac voltmeters. 8. Using output tappingof 6 V & 9 V of the step- down transformer, supply 6V & 9 V to the coil P, in turn , & note down the readings of the both the AC voltmeters in each case.
- 13. Observations Sl. No. Input AC voltage Vp (V) Output AC voltage Vs (V) Ratio V𝑠 Vp 1. 3 V 9 V 1 3 2. 6 V 6 V 1 3. 9 V 3 V 3 Conclusions 1. Within the limit of experimental errors, the ratio Vs / Vp is constant & is equal to the ratio Ns /Np i.e., the ratio of output & input voltages of a transformer is equal to the turns ratio Ns / Np of the transformer. 2. By appropriate choice of turns ratio Ns / Np we can get a step- down transformer. 3. The coils P & S are placed very close to each other but they are insulated. The power in the primary is transferred to the secondary through mutual induction. 4. A steady DC voltage can’t be stepped up or stepped down by a transformer, because a steady DC current doesn’t produce changing magnetic flux & therefore can’t produce induced voltage.
- 14. Sources of Error Values of current can be changed due to heating effect or due to inaccurate counting of turns of coil. Eddy current can change the reading.
- 15. Bibliography Book References SL Arora Physics Lab Manual Internet References - https://www.microsoft.com/ - https://www.google.com/ - https://www.slideshare.net/ - https://byjus.com/ - https://youtube.com/shorts/ - https://www.bing.com/ - https://in.pinterest.com/