Power problem involving liebert Units circuit boards frying

[MrJam]

These readings where taken from a 300amp main on the line side of the disconnect. The building owner has had two liebert units circuit board fried and asks me to monitor the incoming lines. The voltage continually glitches as in figure one. I don't know what’s causing it but I suspect a large UPS system is to blame. Can anyone explain why? Also figure two occurred after a transfer back to regular power from a weekly generator test. Two phases are 90 degrees apart, which isn’t right at all. Also would this affect the leibert units? Any help would be appreciated. All reading where conducted using a hioki 3196. Please ask any questions I'll get the answers.

 

[MrJam]

Here is figure 1

 

[Skogsgurra]

The voltages are OK. The glitches are practically non-existant. Currents when connecting a device to mains usually look terrible. That is normal and no reason to suspect a problem.

How are the Liebert units fried? PSU or something else? I think that you can forget about mains problems.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[alehman]

I don't see anything wrong there either. Looks like a maybe a motor starting.

 

[MrJam]

PSU was fried along with, what I believe is, a transistor on circuit board