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Author Topic: Power problem?  (Read 1476 times)

Mike Sokol

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Re: Power problem?
« Reply #20 on: May 19, 2014, 12:58:57 am »

Three power supplies in 6 months is certainly suspicious-but consider how many hours you have run without a problem, and how much time you have actually spent with a meter connected.  How likely are you to actually catch an anomaly "in the act"?

That's exactly why I suggested some sort of data logger. Even if there was a voltage spike happening several times a day, you might never see it if you blink at the wrong time. And one other thing comes to mind. I know that big water pump motors can create a big emf spike when the contactor opens up, but what about HVAC compressors? Since there's no zero-crossover switch like you get with a Triac switch, there's got to be a spike which will vary in size depending on what part of the sine wave it occurs. So perhaps this is the time to invest in some SurgeX voltage protection. 

Jonathan Johnson

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Re: Power problem?
« Reply #21 on: May 19, 2014, 04:21:14 pm »

That's exactly why I suggested some sort of data logger. Even if there was a voltage spike happening several times a day, you might never see it if you blink at the wrong time. And one other thing comes to mind. I know that big water pump motors can create a big emf spike when the contactor opens up, but what about HVAC compressors? Since there's no zero-crossover switch like you get with a Triac switch, there's got to be a spike which will vary in size depending on what part of the sine wave it occurs. So perhaps this is the time to invest in some SurgeX voltage protection.

I had a customer whose network would completely lock up for about a minute at fairly regular intervals. We determined that there was a power quality issue, but were never able to find the root cause. There was, however, a large welding/fabricating shop a couple of doors down that could have had something to do with it. We ended up putting in an online UPS on the network gear to overcome the issue.

I'm not proposing a solution, but simply trying to point out that power events can be sporadic, difficult to identify, and sometimes impossible to find the root cause. If you can determine that a voltage sag or spike is occurring on the incoming power feed, you'll probably need to get the power company involved. They do have a financial interest in delivering clean power, as in some states they can be held liable for equipment damage caused by events on their distribution system.
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Stephen Swaffer

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Re: Power problem?
« Reply #22 on: May 19, 2014, 10:47:30 pm »

POCOs usually also have the ability to require their customers to comply with certain conditions (ie soft starts/VFDs on  large motors, etc) to keep from interfering with other customers.  If there is a possibility that incoming power is an issue, I have seen them supply and install data loggers (usually a lot better than you can afford)in an attempt to find the issue-just be diplomatic-you want them to want to help you!
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Steve Swaffer
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