TESTING OF TRANSFORMER

Transformer tests:

There are 5 main tests of a Transformer

1.Polarity Test:This test is used to determine the polarity of primary and secondary.This test is carried out but connecting a voltmeter across the primary and secondary and if the voltmeter reads the sum of primary and secondary voltages then the secondary terminal is of opposite polarity with respect to primary.It the voltmeter reads the difference of the primary and secondary voltages then the secondary terminal is of the same polarity with respect to primary.

2.Dc Kick Test:This test is also used to find the polarity but here we connect ammeter across the secondary.

3.Open Circuit Test:This test is generally done on the Low voltage side of a Transformer and it is used to find the

Constant losses /Iron losses
The shunt parameters
Hysteresis and Eddy current losses

4.Short circuit test:This test is generally done on the High voltage side of a Transformer and it is used to find the

Variable losses/Cu losses
Series parameters

5.Sumpner's Test:In open circuit and short circuit test it is not possible to find Iron and Cu losses together at a time so the exact temperature rise of Transformer cant be detected so Sumpner's test is used to find both Iron and Cu losses at a time.Sumpner's test is also known as BACK TO BACK TEST.

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GENERATOR

GENERATOR: A Generator is a machine which converts Mechanical energy into Electrical energy.These are widely used inside the Power plants for the generation of Power. Generator In general the Generator we see in a Thermal power plant gains its mechanical energy from the Turbine connected to it and this mechanical energy is thus converted into the required Electrical energy by the Generator.I myself experienced a 15 days of internship in a Thermal power plant and the Generator was about the size of a lager hall both in its length and breadth and the output Electrical energy is thus achieved by the use of a Generator.

SWITCHING TRANSIENTS IN TRANSFORMER

Switching Transients: The word Transients is always very Scary for me but not any more hahaaa...........what about you???? Well coming to the point...why do these Switching Transients occur in a Transformer. When the switch is closed when the voltage is maximum...then the flux required by the core is zero and the available flux in the core is also zero and hence NORMAL OPERATION is sufficient When the switch is closed when the voltage is crossing zero...then the flux required by the core is maximum but here the avaliable flux in the core is zero and hence TRANSIENT OPERATION is required Here when the Transient operation takes place then the flux doubles gradually and this is known as Doubling Effect of Transformer.This Doubling Effect causes magnetic in rush current and Damage in the insulation. Using Secondary Harmonic Restraining Coil can reduce all these Drawbacks.

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