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Registered Member #3943
Joined: Sun Jun 12 2011, 05:24PM
Location: The Shire, UK
Posts: 552
I was just probing the secondary side of a transformer I found in the garage and noticed that the sine wave just doesn't seem to look "right" (or at-least from what I have seen on the internet).
Here is a waveform taken with a small resistive load across the secondary side.
Is it just me or do the tops and sides seem a bit flat, or am I just going on about nothing. I normally use batteries or DC supply's for the stuff I do so this is the first time I have measured anything to do with the domestic AC supply. So I am just posting here too see if what I am seeing is normal.
Registered Member #30
Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706
Yes the flat tops are normal. Nowadays there are a lot of rectifier loads that draw high currents at the voltage peaks, and the effect is to squish the peaks down. The power company just lets them squish, because it improves the power factor of said rectifier loads, and it would be expensive to fix anyway.
There is a statutory limit of something like 3% or 5% distortion.
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Mains harmonic distortion?
