"On battery power in response to distorted input." Iout jumps and Vout drops, is it a circuit issue?

[CKNYC]

SMX1500RM2UC running at 10% load for a Poweredge R720 server with dual OEM power supplies on a 20A circuit

An audible click was heard from the outlet the UPS was plugged into, and the NMC indicated a yellow "Warning: On battery power in response to distorted input." error condition which persisted.

Looking through the attached data logs, the Iout went up by ~10% and the Vout dropped from ~125v to 110v - 111v

The UPS was moved to an outlet on a different circuit, and the readings went back to normal. The warning in NMC went away.

On the incumbent problematic outlet, the GFCI reset button was pushed, and the UPS was moved back to the outlet.  The error and NMC Warning returned.

The UPS was moved back to the good outlet, and the fuse was reset in the panel, which was NOT tripped.  The UPS was moved back to the incumbent outlet and both the error readings and the NMC Warning returned.  The UPS was moved back to the good circuit as we await clarity on the incumbent outlet.

Is there something wrong with the circuit?  If so what diagnostic equipment should be purchased for troubleshooting?

[Teken]

I would start by using a quality True RMS multimeter and report back the AC volts on all three prongs.

Next press the TEST button on the GFCI and report back the results. Follow up by resetting the GFCI outlet and test it again with a GFCI Tester and report back the results.

Follow up by inserting any like a lamp to the GFCI outlet and wiggle the plug from side to side / up and down and report back the results.

Complete the inspection by turning off the breaker to this GFCI outlet. Remove the outlet and confirm all wiring especially the ground wire is secure and not touching any other exposed neutral / hot wires.

You’ll want to confirm all the wires at the service panel are also properly connected and secure at the breaker / ground / neutral bars.

Questions Ask . . . 👍