Short Circuit Contributors
Short Circuit Contributors
(OP)
I am interested to ask whether we should include Frequency converters, harmonic filters and capacitors as contributors and model them in calculating short circuit currents.
I was having an impression that motors connected to VFDs do not contribute that much and are negligible, same as capacitors and harmonic filters.
I was having an impression that motors connected to VFDs do not contribute that much and are negligible, same as capacitors and harmonic filters.






RE: Short Circuit Contributors
RE: Short Circuit Contributors
RE: Short Circuit Contributors
BOb
RE: Short Circuit Contributors
There is a lengthy discussion of capacitor fault currents in Conrad St. Pierre's book "A Practical Guide to Short Circuit Calculations."
But I don't think ANSI or IEC standards for short circuit calcs have any guidance regarding capacitors.
RE: Short Circuit Contributors
RE: Short Circuit Contributors
Thanks Rags004 for the R-L-C circuit recap.
Thank you for the reminding me also about the bypass contactors...I am learning a lot from this forum.
RE: Short Circuit Contributors
As a supplier of complete installations comprising converters and harmonic filters, I've been working on Isc calculation on marine HV networks. My conclusions are :
1. For converters:
Only converters with thyristor bridges on network side (ie static frequency converters) can contribute to a short-circuit. They will contribute only if the short-circuit occurs when the drive is regenerating. You can find quite good explanations in IEC61363-1. Calculations are quite difficult as the contribution depends on the operating point of the machine at the time the fault occurs;
2. For harmonic filters and capacitor banks:
Obviously they are never taken into account. Our calculations on a few typical projects have shown that due to the time constants of these R-L-C circuits, they do not contribute to the peak value of the short-circuit current, wich is usually the most critical value to verify.
Hope we are in phase guys?