Load test on transformer
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Transcript of Load test on transformer
LOAD TEST ON TRANSFORMER
NEED FOR LOAD TEST
Load Test helps to determine the total loss that
takes place, when the transformer
is loaded .Load test is used mainly
1. to determine the rated load of the
machine and the temperature rise
2. to determine the voltage regulation and
efficiency of the transformer.
CONTD.. The losses that are generated inside the
Transformer
on load appear as heat. This heats the
transformer and the temperature of the
Transformer
increases. The insulation of the transformer is the one to get affected by this rise in the
temperature
CONTD.. This aspect of temperature rise cannot be
guessed from the electrical equivalent
circuit. Further, the losses like dielectric
losses and stray load losses are not modeled in
the equivalent circuit and the actual loss under
load condition will be in error to that extent.
LOAD TEST ASCERTAINED Hence the only sure way of ascertaining
the rating is by conducting a load test.
WHAT U DO IN A LOAD TEST
EFFICIENCY
EFFICIENCY VS X
REGULATION: 1.Voltage regulation(V.R) is the change
in the
magnitude of secondary voltage from no
load to desired load.
2.This change is expressed as a percentage of
the load voltage.
USE OF V.R. To get the best performance out of your
transformer, you need the lowest possible
voltage regulation
EXPRESSION FOR VOLTAGE REGULATION:
APPROX. EQUIVALENT CIRCUIT
Since, the change in secondary
voltage depends only on the load current, the
equivalent circuit is further simplified
VECTOR DIAGRAM FOR LAGGING PF
FINAL EXPRESSION:
CAUSE OF V.R Thus voltage regulation is because of
resistance and leakage reactance of the
transformer
DISADVANTAGE Large amounts of energy are wasted
It is a stupendous task to arrange a load large
enough for direct loading