a) Discuss the methods used for finding the approximate transformer parameters Rser, Lser, Rpar, and Lpar.
b) Explain what each of the parameters Rser, Lser, Rpar, and Lpar model and show their positions in the transformer's circuit diagram.
Following transformer testing on a 100 WA, 50 Hz, 1000 V:250 V step-down transformer, the following results table was compiled:
|
|
Open-circuit test
|
Short-circuit test
|
|
Voltmeter reading (V)
|
1000
|
505
|
|
Ammeter reading (A)
|
2.5
|
7.2
|
|
Wattmeter reading (W)
|
105
|
88
|
c) From the transformer data and table determine the transformer's equivalent resistive parameters.
d) Likewise, determine the transformer's equivalent inductive parameters.
The transformer of (c) and (d) has an iron loss of 92 W and it is used on full-load with a power factor of one. What are the copper losses when its efficiencies are:
e) 98 %?
f) 84 %?