UPS system MBB, RIB, IOB, coordination

[lielec11]

We are working on a design where the engineer has selected all of the breakers within the UPS to trip at 700A including the maintenance bypass breakers, rectifier input breakers, and inverter output breakers, and load breakers. The mains are set to trip at 800A.

My question is how do we try and coordinate this? Shouldn't the MBB, RIB, and IOB all be set higher than the separate load breakers? I would assume the MBB, RIB, and IOB should all be set at 800A as well, similar to the main since they serve the same load. And we'd only want the load breakers that serve downstream STS to be 700A.

I've shared an image below. The main is the 800A breaker at the top left. The load breakers are the two on the bottom right. The rest are either bypass or UPS input/out breakers.Thoughts?

 

[petersonra]

presumably (s)he knows what (s)he wants. if you have questions, the person to ask is him (or her).

 

[lielec11]

I agree with you however I guess I was more interested in other's general opinions on the matter. Sorry for the lack of clarity in my original email.

 

[ron]

For some better help with the acronyms, this graphic might help.

The RIB (and CB1 if it is present) has to deal with UPS losses and battery recharge, so it is often set higher than all of the other breakers.

If the output CB's and the other bypass breakers are relatively close trip values, it might not be practical for them to be much different than each other when you consider other upstream or downstream breakers in the distribution. Look at the TCC's.