What's the meaning of safety category in a DMM? If the same DMM can be cat 3 to 600V and cat 4 to 300V, then what's it about?
- posted
6 years ago
equipment safety categories
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- posted
6 years ago
In US "high voltage" is defined as something more than 600 V, while in the rest of he world, the IEC limit is at 1000 Vac.
On voltage test equipment, there is an issue with peak voltage and duty cycle. A 6000 V pulse with 1 % duty cycle will dissipate the same as 600 V continuous measurements averaged out. The peak power dissipation is 10,000 times the 600V value and 100 times the average power dissipation.
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- posted
6 years ago
I seem to be rather slow getting to posts...
A meter that is safe making readings on a CD player may blow up when making measurements on a 1000A 480V service. The blow-up may or may not be caused by misuse (but everyone makes mistakes).
Part of this comes from the recognition of the hazard of "arc flash" on high capacity sources. Arc flash can more than ruin your day.
Good reference:
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