UPS Maintenance Bypass Breaker Coordination

[LDPBen]

What is the proper way to coordinate with UPS (Uninterruptible Power Supply 26 33 53) maintenance bypass breakers?

Specifically working with small (less than ~250kW / 400A @ 480v) applications where manufacturer provided maintenance bypasses are often generic and circuit breaker types cannot be easily changed. Assume that manufacturer circuit breaker data is available, but cannot be guaranteed to be the same manufacturer as the other gear and circuit breakers in the building.

To further clarify: this is specifically discussing circuit breaker selective coordination (breaker trip curves), not the withstand rating of the equipment.

Thanks!

 

[ron]

What do you want them to be selective with? Other breakers immediately upstream or downstream in series, where opening any one would de-energize the same equipment? If so, then who cares and lay them right on top of each other where possible and let them all trip together and leave yourself room for other OCPD's that you can save for selectivity.
If it is another device, you will need to post a oneline so we can see what you are talking about. Sometimes you are just stuck with the devices you get if you didn't specify them early on requiring certain adjustable characteristics.

 

[LDPBen]

Attached!

The challenge is that we don't have control over the breakers within the UPS bypass as they are in "standard" panels by the equipment manufacturer. Larger systems (500kw+) are typically made to order, so we can change breakers around, but with smaller systems they're just standard in stock items.

The ideal would be to have the bypass breakers do nothing and act like switches within their rated ampacity. Coordinating the distribution breakers with the UPS input breakers upstream and confirming that the bypass breaker trip curves are outside the trip curves of the other breakers (I.E. the bypass breakers remain closed and their associated input breakers would open.

Note!! The breakers below are shown as 200A, but are in reality 250AT breakers.
Thoughts?

​

 

[ron]

Attached!​

I can't see it.

In any case, the approach where you can adjust characteristics depends on how much room you have on the TCC from other upstream / downstream devices.

Either you set the bypass breakers to be so high they are essentially acting like switches, or to set them on top of the upstream breaker that they are in series with.