Kind of a coincidence here given this thread, but I've been having problems at my shop with the voltage dropping. I recently noticed some of my test equipment going out of calibration or "lock" and started checking into what was going on. As it turns out, the voltage is dropping between 6 - 12 volts at random points during the day. While i thought it was more than a coincidence, a new business went in locally that pulls GOBS of power on a cyclical basis. I went down and talked to one of the guys working there and i was told that they are pulling appr 375 amps on an as needed basis. As such, i made them aware of the problems that i was having and one of the guys started looking things over. When their system fired up, the line voltage was sagging anywhere from 6 to 12 volts. Hmmm... Those are the exact same figures that i had come up with too.
I had already had our local utility provider out to check things over, but they couldn't find any problems. I surmised that this was due to the power dropping at random i.e. it is not a constant problem. As such, i guess i'll have to get them back out there and possibly change the transformer. The tech that had looked at it told me that it was VERY old and was what was feeding the whole grid in our area. As far as i know, i think that this transformer also feeds a portion of local residences within the area too. I have to wonder what it's doing to them ???
As a side note, a 375 amp draw is equivalent to appr 44 KW's of power. While i don't know the going rate for electricity in terms of KW per Hour around here, we assumed it was less then $0.10 per KW. At that rate, it costs that business $4.40 per hour for electricity when all of their equipment is running full tilt. As such, i thought that was pretty reasonable given the amount of power being consumed. Sean
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