UPS: Bypass not in range ; either frequency or voltage.

[Anonymous user]

Hello, I need some help to understand the behavior of my ups. The model SKU is:SRT8KRMXLI it is wired on 3 phase + n on the main and it is connected in a genset transfer switch. The problem occurs only when the main voltage goes out and the transfer switch of the generator automatically transfer the UPS power to the Genset. We measured the quality of the 3 phase produced by the generator and it appears to be perfect, 230V per phase (related to neutral) and 50.2 Hz. Even the waveform appears to be perfect. That being said when the the ATS switch between the mains power to the generator each time different errors appears ( distorted waveform, low voltage and things like that) of course we have measured everything and they are correct. Below you van read the latest log.  I hope there is something in the configuration of the unit that I miss so can set correctly. We have others APC UPS powered by this genset and they are not affected by this issue but they are quite older than this one. Hope someone can help me to understand this problem better.

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[BillP · Accepted solution]

Hi Americo,

The UPS's data logs are not very granular, they only record once every 15 minutes, so they might miss any issue.

Can you map out the circuit for me, does it go generator/mains, ATS, UPS or the other way around, what model ATS are you using?

Is it possible that the generator was correct at time of measuring but that it is not consistent, it would be rare for a generator to provide perfect voltage and sine wave. 

-Gavan