Tuesday, 3 April 2018

Anyone Know What is Back To Back Test Or Sumpner Test! !?

Anyone Know What is Back To Back Test Or Sumpner Test! !? 




What is Used Of Back To Back Test And We Can Apply The Back To Back Test In Transformer!! 




This Test On Transformer is performed for finding efficiency, regulation and heating (Temperature Rise) under loaded conditions.



The O.C. and S.C. tests on Transformers are conducted to determine its performance i.e. efficiency and regulation without actually loading the transformer but cannot give heating information under Load Condition.


In Sumpner's Test, actual loading conditions are simulated and hence it is more Accurate Method of determining the efficiency and regulation than O.C. and S.C. tests

(A) 

Two Transformers Of Identical Rating are needed to perform this test Figer(A) shows the experimental circuit diagram for performing Sumpner's test on two identical rating single phase transformers .




The Primary Windings of two transformers are connected in parallel and are energized at rated voltage and frequency with the Secondary Windings open.


  • As secondaries of both transformers are open, The Wattmeter W1 reads the iron losses of both transformers. The secondaries of both transformers are connected in phase-opposition.

  • Their polarities can be checked by means of voltmeter connected across the switch If The Voltmeter reads zero, it means that the secondaries are in phase opposition and the switch (S) can be closed.


In case the voltmeter reads the secondary voltages, the secondaries are in same phase.

order to bring them in phase opposition, interchange Secondary Terminal of one of the transformer



A Reduced Voltage (hardly 5 to 10%) is applied across the secondary windings so that full load rated currents flow in both the secondaries and by transformer action, the primary windings also carry rated full- load currents.


  • As the Applied Voltage is very low, the iron w be very small and can be neglected.


A single phase variac can be used in the secondary circuit to obtain a reduced voltage.


As the full-load current is flowing in Secondary Circuit, the wattmeter reads full load copper losses of both the transformers.



Questions Related Back To Back Test :


(1)sumpner test is use for????
Ans: This test on transformer is performed for finding efficiency, regulation and heating (temperature rise) under loaded conditions.


(2)what is advantage of sumpner test?? 
Ans: In sumpner's test, actual loading conditions are simulated and hence it is more accurate method of determining the efficiency and regulation than O.C. and S.C. tests.


(3)which and how manny transformers are use in sempner test?? 
Ans:Two transformers of identical rating are needed to perform this test .



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