Breaker loss of gas, Trip or no Trip 1

[cranky108]

Within our group we have been discussing the breaker gas alarms, and if it is better to Trip the breaker on low gas pressure, or to block Trip for loss of gas. The breakers can do either, and the advantage depends of how quickly the gas is lost.

With that, I would like to hear other perspectives?

 

[slavag]

Hi cranky108.

NO TRIP and NO BLOCK. you block trip by low-low gas only, and this block must be provide by CB mnf by HW.

Yep it;s also possible provide trip by low gas, but not seems, as good solution,
What you can do, send signal low-low gaz to your BFP system for shorted time of BFP.

Just my opinion.
Best Regards.
Slava

 

[patrick7961]

Hello,
The utility I was at always tripped for low gas.

 

[oldfieldguy]

Assuming pressure dropping. First, alarm. Second, TRIP, third, block trip.

Having the breaker trip when gas pressure is still high enough for tripping to be safe insures that you won't have a breaker sitting in the yard that WON'T trip when the system is in trouble. Most grids can stand a single breaker opening, but a single breaker FAILING to open starts various breaker failure schemes that turn off a lot of lights very fast.

old field guy

 

[cranky108]

As the discussion have gone, it depends if the leak is a fast leak, there may not be time for a breaker trip. But that has to be a very large leak. If the leak is a slow leak, tripping the breaker actually helps, in that opening the breaker saves having to open several other breakers.

Presently we block trip for very low pressure. And the though is maybe that isen't the best practice.

Yes we alarm first.

 

[climb1]

from breaker side:
most breakers will have significant damage to the interrupter if operated without any gas, if the leak is that big.

what i have seen is a time delay on the low gas contacts, and if the breaker reaches third lock out stage before time delay closes, it will keep from tripping.

there is probability in fast leaks occurring, but in my experience i have not seen one that leaks 'very fast'.

 

[PHovnanian]

I like the "Slow leak, trip. Fast leak, block" scheme. Following a low pressure block, a subsequent protection trip command should be routed immediately to whatever backup logic one sends their breaker failure signals.

 

[zaza123]

In my opinion a slow leak shall give an alarm. If slow leak will trip there will be Emergency & many things connected will trip
Slow leak -Alarm
Then you can do the changeover on the downstream system & loadchangeover to be done. When there is no load on breaker you can easily trip the breaker.
If the amount of gas leak is more than it should give an alarm & Block the tripping.