Physics Project Report: Submitted To: Submitted by

2020-2021

PHYSICS PROJECT REPORT CONSERVATOR TANK

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It is to certify that

of class

XII-A, RATTAN CONVENT SCHOOL has completed his project file under my supervision. He has taken proper care and shown utmost sincerity in completion of this project. I certify that his project is upto my expectations as per the guidelines issued by C.B.S.E.

MR. VINOD

I would like to express my special thanks of gratitude to my teacher who gave me the golden opportunity to do this wonderful project on the topic , while working on this project i came to know about so many new things. Secondly i would also like to thank my parents and friends who helped me a lot in finalizing this project within the limited time frame.

INTRODUCTION PRINCIPLE CONSTRUCTION THEORY AND WORING EFFICIENCY ENERGY LOSS USES BIBLIOGRAPHY

INTRODUCTION A transformer is one of the most common devices found in electrical system that links the circuits which are operating at different voltages. These are commonly used in applications where there is a need of AC voltage conversion from one voltage level to another. It is possible either to decrease or increase the voltage and currents by the use of transformer in AC circuits based on the requirements of the electrical equipment or device or load. Various applications use wide variety of transformers including power, instrumentation and pulse transformers. In a broad, transformers are categorized into two types, namely, electronic transformers and power transformers. Electronic transformers operating voltages are very low and are rated at low power levels. These are used in consumer electronic equipment like televisions, personal computers, CD/DVD players, and other devices. The term power transformer is referred to the transformers with high power and voltage ratings. These are extensively used in power generation, transmission, distribution and utility systems to increase or decrease the voltage levels. However, the operation involved in these two types of transformers is same.

PRINCIPLE OF TRANSFORMERS A transformer is based on . the principle of mutual induction,

i.e., whenever the amount of magnetic flux linked with a coil changes, an emf is induced in the neighbouring coil

CONSTRUCTION A transformer consists of primary and secondary coils insulated from each other, wound on a soft iron core. To minimize eddy current a laminated iron core is used. The a.c. input is applied across the primary coil. The continuously varying current in the primary coil produces a varying magnetic flux in the primary coil, which in turn produces a varying magnetic flux in the secondary. Hence, an induced emf is produced across the secondary. Let EP and ES be the induced emf in the primary and secondary coils and NP and NS be the number of turns in the primary and secondary coils respectively. Since same flux links with the primary and secondary, the emf induced per turn of the two coils must be the same.

THEORY AND WORKING The working of the transformer is explained below. The transformer consists of two separate windings placed over the laminated silicon steel core.

The winding to which AC supply is connected is called primary winding and to which load is connected is called secondary winding as shown in the fig. below. It works on the alternating current only because an alternating flux is required for mutual induction between the two windings.

When the AC supply is given to the primary winding with a voltage of v1, an alternating flux  sets up in the core of the transformer, which links with the secondary winding and as a result of it, an emf is induced in it called Mutually induced emf. The direction of this induced emf is opposite to the applied voltage v1, this is because of Lenz’s law.

Physically, there is no electrical connection between the two windings, but they are magnetically connected. Therefore, the electrical power is transferred from the primary circuit to the secondary circuit through mutual inductance. The induced emf in the primary and secondary coil depends upon the rate of change of flux linkage i.e., (Nd/dt).

d/dt is the change of flux and is same for both the primary and secondary coils. The induced emf in the primary winding is directly proportional to the number of turns of primary coil. Similarly, induced emf in the secondary coil directly proportional to the number of turns in the secondary coil.

TRANSFORMER ON DC SUPPLY: As discussed above, the transformer works on AC supply, and it can not work on DC supply. If the rated dc voltage is applied across the primary coil, a constant magnitude flux will set up in the core of the transformer and hence there will be no self-induced emf generation, and as for the linkage of flux with the secondary coil there must be alternating flux not a constant flux.

According to OHM’s Law: PRIMARY CURRENT

=

DC APPLIED VOLTAGE

RESISTANCE OF PRIMARY COIL

The resistance of the primary coil is very low, and the primary current is high. So, this current is much higher than the rated full loaded primary coil current. Hence, as a result, the amount of heat produced will be greater and therefore eddy current loss will be more. Because of this, the insulations of the primary coil will get burnt, and the transformer will be damaged. Turn ratio: It is defined as the ratio of no of turns in the primary coil to that of the secondary coil. Turn ratio = N1/N2 If N2>N1 the transformer is called step up transformer. If N2