Capacitor Bank Protection

[WattsNew]

Does anyone know of a standard/book related to capacitor bank damage curves? I need to plot this on a TCC and no software I know offers this capability.
Thanks in advance!

 

[DanDel]

Since a capacitor bank will only draw a fixed current based on the voltage and frequency applied, I'm not sure what kind of damage curve would apply. Can you clarify your application?

 

[WattsNew]

Capacitor banks utilize group fusing. The fuse should have a time-current clearing charactersitic that lies below the time current case rupture probability characteristic of the capcitor units. THere are 4 zones defined by 3 such curves - Safe Zone, Zone 1, Zone 2 and Hazardous Zone. Finally there is a inrush current similar to a transformer which has to be indicated on the TCC.

 

[rbulsara]

Norm is to size capacitor fuse to 135% of rated current of the capacitors. I think its Code also in USA.

You may wish to ask some manufacturers. But I am not sure damage curve applies to capactitors while any device may have some kind of withstanding capability for some current for sometime. I am not sure caps have any significant overcurrent withstand capability.

Damage curve comes only in play when a device (such as a cable or a transformer) has to continue under overload conditions to keep the system still powered up, untill some protective device opens. This does not apply to capactor banks, in fact they can and should come off line as soon as possible. Because keeping capactiors (assuming they are PFC) on line is not essential to keep the service running.

You do not want to size fuse any larger than it need to for capacitor bank at any rate.

 

[Sett]

Hi Tanuj!

Reviewing the standard IEEE C37.99-1990 "IEEE Guide for the Protection of shunt Capacitor Banks" I dont found nothing about it.

I recommend Ask to manufacturer!

Good Luck!!

 

[WattsNew]

Sett. I am doing the same thing at this point. IEEE C37.99-1990 "IEEE Guide for the Protection of shunt Capacitor Banks" has some good information but nothign related to the rupture characteristics. Search continues. Thanks.