Weird UPS Battery Issue.

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BGomolka

Member
Location
Denver
Occupation
Electrician
Hello,

I am curious if anyone can take a gander at what this electrical problem could be.

They are experiencing sporadic events a few times an hour in which new lithium battery cabinets there were installed are discharging or charging for an extremely brief period. See video below. Samsung says this is not normal for the cabinets. The old batteries did not have any type of monitoring to catch this event (if it was occuring). These each have their own computer to record the data.

All 9 UPS are fed from the same Medium Voltage "B" building feeder. Each B2, B3, and B4 are separate substations which each have 13.2kv to 480v transformers.

My first thought - Theoretically, Could a large inductive load (either in the building or even neighboring buildings) on the medium voltage feeders cause a momentary dip or spike in the 13.2kv line, pass through the separate transformers, and cause each of the UPS rectifiers to simultaneously spike or dip the DC bus voltage for a moment - thus causing the quick discharge/charge event? if the DC bus voltage goes down from 535v, the cabinets would show discharging, and if it spikes above, cabinets show charging. This quickly levels out once the spike goes away and the DC bus voltage is stabilized. The UPS are not new.

Video Link -
 

Hv&Lv

Senior Member
Location
-
Occupation
Engineer/Technician
~28% dip..
Possible, but very briefly and shouldn’t be often. Is there any delay on these or are they instantaneous?
I realize UPS and instantaneous, but I’m curious if they are doing this if the AC blip is say 2-5 cycles.
 

BGomolka

Member
Location
Denver
Occupation
Electrician
That's what I am trying to figure out. I'm going to throw a fluke 3 phase power quality analyzer / logger on one of the 480v UPS feeds today. I am hoping that I pick something up that correlates with this.

What do you mean 28% dip?

Are you asking if there is a delay in recording? The battery cabinets react instantaneously as its an active double conversion style UPS (all liebert 610's). The battery cabinets are always online and connected to the DC bus of the UPS. If the AC to DC rectifier on the UPS loses AC power due to outage or input breaker tripping, the DC bus is powered solely by the battery cabinets and current starts to get pulled from the batteries instantaneously.
 
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