7.2 Circuit breaker used in 4.16 kV

[lume7006]

Hello,

One circuit breaker was designed using IEC standards, it is 7.2 kV and its maximum interrupting current is 20 kA at 7.2 kV.
However, this one is used in 4.16 kV.

My question is:
How can we determine the maximum interrupting current at the operating voltage????

Any suggestions/ideas will be welcome!

 

[dpc]

You need to get the data from the manufacturer. It will be at least as high (in amps) as the 7200 V rating and probably higher.

 

[whycliffrussell]

dpc. yes, with a BUT:

"older" breakers were rated with a nominal I.C. for the nominal voltage and a maximum I.C for the max rated voltage, AND the I.C for every point in between was CALCULATED as:

I.C (At Voltage V)= ((Voltage V)/(Nominal V))*Nominal I.C.

NOWDAYS, most NEWER breakers appear to be maximum rated devices, that is the I.C. on the breaker is the maximum that it is rated for.

I would contact the Mfg (or check out the data for the breaker online if available), and see if it is maximum rated device.