capacitor bank fusing

[trackatino]

CAN ANYBODY HELP ME CALCULATE THE FUSE RATING FOR THESE PARAMETERS
INCOMING VOLTAGE=11KV
CAPACITOR BANK RATING= 200KVAR
KINDLY PROVIDE FORMULA USED.thanks

 

[waross]

Most utilities will have fusing tables for capacitor banks and transformers. Remember that capacitor voltage is proportional to the square of the voltage. Make allowances for over voltage operation.
Comparison example;- Canadian Electrical code.
Motors conductor ampacity> 100% plus 25% of largest motor.
Transformer conductor ampacity> 100% plus 25% of largest motor.
Capacitor conductor ampacity > 135% (CEC Rule 26-208,(1))

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[achimedes]

Even with the fusing table of utilities, how is the fuse rating calculated with a supply voltage of 11kv and a capacitor bank rating of 200kvar. Thanks.

 

[pwrtran]

Vll=11kV
Var_3Ph=200kVar
Icap=200/(1.732*11)=10.5A

As per IEEE 1036-1992, Section 4.4.1, the minimum fuse size is no less than 125%~135% of the capacitor current. In your case > 15E is ok
As per Canadian Code (OESC 23rd Edition) 26-210, the overcurrent device shall not exceeding 250% of the rated current of the capacitor.
We normally use 150~200% and also verify the capacitor damage curves obtained from the manufacture.

 

[magoo2]

200 kvar looks more like a single-phase can rating than a bank rating. Is it really a 200 kvar bank or a 600 kvar bank?

 

[pwrtran]

magoo2

Thanks for addressing that point. 200kVar really sounds odd for 3Ph...