edison123
Electrical
- Oct 23, 2002
- 4,451
This week, we trialed a 125 KW VFD for testing LV motors in decoupled condition. During the trials, I noticed our LED lights started flickering even though they were switched off.
When asked, the OEM drive guru said there will be harmonics fed into the system, and we need to install an isolation transformer to prevent harmonics getting back into other loads.
Is this correct? If yes, what will be transformer connection, delta input/wye output, or delta/delta or wye/delta?
What will be the KVA rating of the isolation transformer?
If isolation transformer is required, can I go for 415 V input / 690 V output so that I can get a 690 V VFD output for testing some motors which are rated at 690 V?
Will a 690 V VFD give 415 V output (which will be the 95% of the motors we test) without any derating in current capacity?
When asked, the OEM drive guru said there will be harmonics fed into the system, and we need to install an isolation transformer to prevent harmonics getting back into other loads.
Is this correct? If yes, what will be transformer connection, delta input/wye output, or delta/delta or wye/delta?
What will be the KVA rating of the isolation transformer?
If isolation transformer is required, can I go for 415 V input / 690 V output so that I can get a 690 V VFD output for testing some motors which are rated at 690 V?
Will a 690 V VFD give 415 V output (which will be the 95% of the motors we test) without any derating in current capacity?
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