Switchgear Circuit Breakers

[sonic02]

Hi All,

I'm adding four(4) new, 15kV metal-clad switchgear breakers to an existing line-up. I plan to utilize DC power for the tripping, closing, spring-charging and protective relay. Now, my concern is whether the existing battery cells have the adequate capacity (i.e. battery voltage)to provide what I need.

What should I do to ensure or how do I make a check if the battery cells have the some spare capacity for my application.

Appreciate your inputs.

 

[pwrengrds]

Figure out how much capacity you have from the batteries. (how many amp hours are in the battery)
Figure out how much capacity you currently use or need to have to hold in reserve. (what loads you have currently and how many time you want to be able to operate them and for how long)
Figure out how much capacity you will add. (what load you will add and how long they will need to operate or how many times)
Do the math.

Test the batteries if needed if there is some reason to believe that they are weak.

 

[Marmite]

Another thing to bear in mind is the standing load of your protection relay. Your existing breakers may have electromagnetic relays with no standing drain, wheras new relays are likely to be electronic. Depending on the type of circuit breaker there may be an electronic control module with a standing load. If you do have standing loads you would need to check the charger output is sufficient.
Regards
Marmite

 

[mgtrp]

Battery bank sizing is covered in several IEEE standards, perhaps IEEE 485 (from memory) might be suitable for you.

There is more to it than you might initially consider, although it is not that complicated to work through.