Page 366 - Practical Power System and Protective Relays Commissioning

Chapter 21

A Guided Practical Value of

Some Test Results Collected
From Actual Power System

Testing at Site

21.1 POWER TRANSFORMER TEST
Example 1:
75/75/25 MVA transformer
220/70/11.5 kV F 5 50 Hz
1. Insulation resistance of winding
Injected voltage 5 5kV DC
High voltage (HV)—E 1250 MΩ
Low voltage (LV)—E 3000 MΩ
HV—LV 4000 MΩ
Tertiary—E 3000 MΩ
HV—tertiary 5000 MΩ
LV—tertiary 3500 MΩ
2. Wiring insulation
Injected voltage 5 1000 V
R . 1000 MΩ
3. Fan motor consumption
I N 5 1.8 Amp
I Start 5 7.62 Amp
Example 2:
125/125/45 MVA
220/70/11.5 kV
1. Audio noise level test
Average level of noise 5 77 dB

Practical Power System and Protective Relays Commissioning.
DOI: https://doi.org/10.1016/B978-0-12-816858-5.00021-6 361
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