Breaker nameplate minimum voltage

[wbd]

Hello,

Could someone explain what the minimum voltage rating means on a circuit breaker. The breaker is a Square D Type FG2 with the following nameplate information:
Continuous Current 1200 Amps
Minimum Voltage 13.8 kV (although manual lists this as 11.5 kV with 13.8 kV as a nominal voltage)
Maximum Voltage 15.0 kV

My concern is that this breaker is used in an application where the voltage is 6.6 kV. I can understand a maximum rating but why a minimum voltage rating?

Thanks in advance to all replys.

 

[mesutphen]

I've only seen this used for a "constant MVA" approach to short circuit rating. This approach was dropped a while ago. Basically, the symmetrical interrupting capability of a breaker was increased as the voltage was decreased (hence constant MVA) down to the minimum voltage. Below the minimum voltage, the interrupting rating stayed the same.
Like I said, this approach was dropped a while ago. Functionally, the breaker will operate the same at 6.6KV, you shouldn't have any issues.

 

[Kiribanda]

wbd,
Previously ANSI bkrs were classified as "constant MVA" and therefore "Voltage Range factor (K)" was defined.Your bkr must have K=1.30 printed on the name plate.That
means it can operate from 11.5 kV to 15.0 kV range. Accordingly the rated sym. interrupting capability varies from 23 kA to 18 kA.Now, ANSI C37.06 is harmonized with
IEC 60056, therefore now K=1.0.