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Red Chinese 20 Amp variac overload at 4 volt and 40 volt when turning dial fast
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robsims:
Hi,

I have a red Chinese 20 Amp max Variac. When i turn the dial fast in clockwise direction my multimeter shows OL at 4 volts and at 40 volts. When i turn the dial very slow i don't get the Ol message on my multimeter. When i turn the dial counter clockwise i don't get any OL message on my multimeter. Anyone know what the problem might be?
TMM:
I assume your multimeter is 4000 or 40000 counts? The multimeter shows "OL" (over-limit) briefly when the value reaches the limit of the range and it has to change up to the next range. This is normal. When you turn the variac slower it can probably change to the next range before the reading reaches the over-limit, therefore doesn't need to display "OL".
robsims:
Many many many thanks TMM. Yes the multimeter shows OL briefly. I have two Extech MN16A multimeters and indeed they are 4000 counts. Problem solved. Thanks again
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