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SMT750 and Cat generator

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mahohmei_apc
Cadet
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107

SMT750 and Cat generator

This was originally posted on APC forums on 9/5/2016


At my workplace, we have a load connected to an SMT750, but the building is backed by a Cat diesel generator. We recently had a 2-day power failure due to a hurricane, but the generator had more than enough fuel for this. City power failed at 2332, and I got the following 7 times during the failure; 5 within the generator's first hour:

 09/01/2016    23:32:47    Device    UPS: RFC1628 MIB alarm entry removed.
 09/01/2016    23:32:47    Device    UPS: RFC1628 MIB UPS is no longer battery.
 09/01/2016    23:32:47    Device    UPS: No longer on battery power.
 09/01/2016    23:32:46    Device    UPS: RFC1628 MIB UPS is on battery.
 09/01/2016    23:32:46    Device    UPS: On battery power in response to distorted input.

I also got two entries of "UPS: On battery power in response to rapid change of input.", also within an hour of the generator coming online.

Is this to be expected as a generator engine stabilizes/warms up in its first hour?

Thanks!


Accepted Solutions
voidstar_apc
Janeway
Janeway
0 Likes
0
107

Re: SMT750 and Cat generator

This was originally posted on APC forums on 9/5/2016


Short answer: You should find a sensitivity setting in the LCD menus that can minimize these nuisance transfers. If it's only two nuisance transfers, it might not be worth worrying about.

So, computer power supplies have a holdup time during which they can ride through loss of power. The UPS needs to respond faster than the holdup time to protect the computer which means responding to slight changes in line condition. The LCD menus should have a sensitivity setting you can adjust so the UPS is less prone to overreact at the expense of being slower but still within the holdup time. You generally want the highest sensitivity that doesn't cause problems with your generator because as the equipment ages it can become less able to ride through interruptions, and of course some equipment may not meet spec.

See Answer In Context

1 Reply 1
voidstar_apc
Janeway
Janeway
0 Likes
0
108

Re: SMT750 and Cat generator

This was originally posted on APC forums on 9/5/2016


Short answer: You should find a sensitivity setting in the LCD menus that can minimize these nuisance transfers. If it's only two nuisance transfers, it might not be worth worrying about.

So, computer power supplies have a holdup time during which they can ride through loss of power. The UPS needs to respond faster than the holdup time to protect the computer which means responding to slight changes in line condition. The LCD menus should have a sensitivity setting you can adjust so the UPS is less prone to overreact at the expense of being slower but still within the holdup time. You generally want the highest sensitivity that doesn't cause problems with your generator because as the equipment ages it can become less able to ride through interruptions, and of course some equipment may not meet spec.