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From: firstname.lastname@example.org (milne_v)
Subject: Re: Why is the home voltage so high ?
Date: 3 Oct 2002 12:15:23 -0700
NNTP-Posting-Date: 3 Oct 2002 19:15:23 GMT
"News2020" wrote in message news:...
> I measured the voltage at the power outlets at home and found it to be close
> to 140 V.
> This is way beyond the expected range (110-120) ?
Do you have access to a scope? If yes then scope the mains, use a step
down transformer if you don't feel comfortable working at mains
Look for narrow spiked transients on mains sinewave. Could be at zero
crossing, could be elsewhere. If they are there, then these transients
can easily be the source of many of your problems. Make sure that
triac dimmers and inductive motor alliances in the home are off at the
time. If you find transients then move on to the homes grounding
system and scope a grounded metallic structure using an external
ground stake as a grounded referance. If transients also appear on the
homes grounded structures, then you have identified at least part of
your problem. Don't confuse the transients with power line
frequencies. They will produce very broad band RF. If they appear on
grounded structures with triacs and motors shut off then I doubt
whether the source is within the home. These transients can and will
produce nasty resonant harmonics in operating appliances. Should they
appear on grounded structures then you can assume that whatever is
producing them is not a toy. It's probably a high powered source in or
around your home that encorporates some type of high powered arc
discharge or some high powered line switching device. You can also use
a computer with sound card, a program such as "cool edit" and some
shielded cable with the appropriate plugs to record the grounded
structures signals with no danger and then analyze the waveform
looking for the same type of thing. Should these transients be present
then it's safe to say that they don't belong there. Should transients
be present then they will probably produce RFI harmonics that are
easily picked up on the lower end of a portable AM radio. If you get
as far as finding the RFI on the radio, then use the radio to check
for sources in and around your home such as your hydro meter and
neighbouring hydro meters. This can be used to determine if the
problem is specific to your neighbourhood or specific to your home.
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