Reduced voltage/ lights dim

[Nietz001]

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• <font size="2" face="Verdana, Helvetica, sans-serif">I'm having trouble with low voltage issues. The building occupants have reported lights dimming, UPS's coming on,( for a few seconds) and had a computer server down. I contacted the utility Dept and they checked their readings for the last 2 months. Everything was normal. I have checked the building for large unusual loads, Magnets, motors, capacitors, ect... nothing jumps out as a problem. The low voltage does seem to be spread out over several different panels so I think the problem would be coming from the main service, but I'm not even positive of that. Anyone out there been through something like this? Help! Thanks Jeff
  Point of interest, 2 elevators are being upgraded, this might be the problem, so I checked and the 2 main transformers are both 2000kva. Thats not a large load for 2000kva transformers.</font>

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[ December 20, 2005, 12:59 PM: Message edited by: Nietz001 ]

 

[Tom.Margillo]

Re: Reduced voltage/ lights dim

Is there a transformer? Could be the prblem.

 

[charlie b]

Re: Reduced voltage/ lights dim

At a previous place of employment, I was involved in the investigation of a similar problem. It was at a six-story condominium. The problem occurred when the elevators were started, but not every time the elevators were started. I had convinced myself that it only happened when both elevators were started within moments of each other. That would have to take place once in a while, and it would explain the relative rareness of the light flickering problem.

It wound up being our position that the root cause of the problem was an undersized service transformer. The impact of a simultaneous starting of two 40 HP elevator motors was too much for the transformer to handle, and the resulting voltage dip caused lights to flicker and computers to crash. However, the owner and the utility did not agree, and the occupants started the process of bringing their complaints to court. I did not hear how the case turned out.

 

[benaround]

Re: Reduced voltage/ lights dim

Jeff,

I too had a similar troubleshoot, lights blinking,dimming,etc. and it to was when the elevator started.
It turned out to be (as you mentioned)the main equipment had a loose connection on one of the bus bars,it was getting red when I found it!
This was a new building and we took the job over as the GC was afraid the EC couldn't handle it,poor workmanship.

 

[beanland]

Re: Reduced voltage/ lights dim

I may be a little late on this but utilities base the transformer size on average load. Utilities generally do not consider themselves responsible for supplying a large transformer to mitigate the customer-equipment-caused voltage dips. I agree with others: look for bad connections (IR scan) and look for large load starting (HVAC, elevators, etc.) Also, poor/loose neutral could appear as intermittent high/low voltage. Soft-start may be required on motors to help mitigate any low voltage problem they care causing.