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A star connected 400V, 50Hz, 4 pole synchronous machine gave the following open circuit and short circuit test results :
Open circuit test : Voc = 400 V (rms, line-to-line) at field current, If = 2.3 A
Short circuit test : Isc = 10 A (rms, phase) at field current, If = 1.5 A
The value of per phase synchronous impedance in Ω at rated voltage is _____________
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- 156
- 15.06
- 16
- 5.06
Correct Option: B
For open circuit test :
VOC = 400 V (L – L)1 If = 2.3 A
For short circuit test :
ISC = 10 A (phase), If = 1.5 A
We know, 
| ∴ ISC = | × 10 = 15.33 A | |
| 1.5 |
| ∴ Zs = | ||
| ISC |
| = | = 15.06 | |
| 15.33 |
= 15.06 Ω / ph
