Any negative impact for increasing upper limit?

[APC_Customer]

I have a mix of SMTL1000RM2U and SMTL1500RM3U UPS's. Rated output voltage 120 VAC and Output Upper Limit 127 (default). In normal operating conditions, the UPS' input voltage is 120V to 122V. We recently had a power outage and after our generator kicked in, some of our UPS's would not turn on and displayed a "waiting for AC" error message. I could still access the NMC web GUI of these problematic devices and discovered that they had an input voltage of 140V+. My understanding is that with the default limit of 127V, the UPS can receive up to 139V (127 x 1.1), 10% being a given variance. Please correct me if my understanding is wrong. When I changed my upper limit value of 127 to 136 (the highest allowed), the outlet turned on, presumably because the units can now accept up to 149V (136 x 1.1).

Aside from seeing if facilities can reduce the generator's voltage output, is there any downside to keeping the Output Upper Limit to 136 (efficiency, lifespan of UPS, etc)? I also think the setting should be renamed to Input Upper Limit since from the UPS's perspective, it's input power from the wall socket. Any thoughts would be appreciated.

[Teken]

There is no impact on the UPS itself as it’s designed to operate in this voltage region.  The vast majority of consumer electronics today are dual voltage and frequency.

As such are capable of operating on 120~240 VAC 50/60 Hz. Having said this electronics that are not dual voltage are designed to operate no higher than 130 VAC.

If your sites generator is truly outputting 140 VAC there’s going to be lots of magic smoke coming to a town near you! 🤦‍♂️🤣

Anything that isn’t protected by a AVR, UPS, 1:1 Transformer, will begin to deteriorate.

Bottom line the generator needs some maintenance and fine tuning! 

Questions Ask . . . 👍

[APC_Customer]

Thank you for the response. All of our equipment sits behind a UPS. If there is no downside or negative impact to the UPS if it receives 140+V and the UPS is rated to handle it, why is the default 127V instead of the maximum configurable value of 136? From my understanding, the UPS is going to take that input and adjust accordingly to output as close to 120V to the connected equipment. A default value of 136 would have prevented downtime for my organization in this scenario.

[Teken]

As stated up above anything over 130 VAC will result in damage to electrical devices not so rated.

The default of 127 VAC is considered within the tolerance of the POCO and electrical standards.

I must stress again do not arbitrarily increase the upper input voltage limit until you validate the attached equipment is designed to accept the same! ☝️