Any one with Isolated Phase Bus - GCB Experience ? Need your assistance.

[ArcEnergy]

Hello all,

I have a question regarding the IPB in connection with completely enclosed Generator switch gear. Might be a little confusing.

The IPB data shows the average temperature rise of 50K at the ambient temperature of 40°C. At the generator circuit breaker terminal, the contacts have an allowed temperature rise of 65K. That means, when the IPB is connected to the switchgear, there is a possibility of the heat flow from switchgear module into IPB.

Now my question is how much temperature rise is allowed inside the IPB. The manufacturer guaranteed that his IPB will never have a temperature rise above 50K in any cases. I mean if his IPB is rated for the current of 12.5kA, then as long as the current value is below 12.5kA, the average temperature rise will never go over 50K,

I am at the moment testing the generator switchgear with an IPB (rated for 12.5kA current) of 2m long connected to the switch gear and a test current of 11.5kA is applied. During the test I have observed that the IPB had a temperature rise around 60K when measured 1m away from the connection terminals. I assume it is because of the over heating of circuit breaker terminals (rise was above 65K). Since the manufacturer has guaranteed that his 12.5kA IPB will never have a rise more than 50K, can I apply some forced cooling to the IPB in my test and bring the rise to 50K and let more current pass to circuit breaker (may be 12.3kA or so) ? . Will that make sense? .

Some opinions from your side will be highly appreciated.

 

[ArcEnergy]

None of you had an experience with IPB-GCB combination?

 

[ScottyUK]

Other than current rating we don't know anything about either the bus or the breaker. You need to engage the manufacturers involved - at this power level guesses are likely to be expensive, especially guesses based on virtually no information.