Is it possible to measure a voltage beyond what your multimeter is capable of measuring by measuring the amps providing you know the resistance? Just wondering if the voltage would still harm the meter.
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1\$\begingroup\$ How high are we talking about? Why not setup a resistive divider? (Also take into account the breakdown voltage of the resistors themselves, in which case you can use many in series). \$\endgroup\$– Wesley LeeOct 9, 2017 at 2:56
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\$\begingroup\$ Were talking around 2K VAC. \$\endgroup\$– user1897830Oct 9, 2017 at 3:02
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\$\begingroup\$ If you can accept some small error, get a cheap TekPower TP7040 ( amazon.com/dp/B0006GD7NU ) which already does 1000 VAC at \$9\frac{\textrm{k}\Omega}{\textrm{V}}\$; \$9\:\textrm{M}\Omega\$ input resistance at the \$1000\:\textrm{V}\$ setting. Add four \$2.2\:\textrm{M}\Omega\$ resistors in series into the plastic body of one of your probes. (Four because they usually stand off \$200\:\textrm{V}\$ each.) You really want them to be \$9\:\textrm{M}\Omega\$, but the slight added error is probably okay. The meter already has 4% error spec; another few % may be fine. \$\endgroup\$– jonkOct 9, 2017 at 6:12
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\$\begingroup\$ Thanks Guys, I think I will just build a voltage divider. \$\endgroup\$– user1897830Oct 9, 2017 at 12:44
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\$\begingroup\$ Please don't add "thank you" as an answer. Instead, accept the answer that you found most helpful. - From Review \$\endgroup\$– RicardoOct 9, 2017 at 14:10
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2 Answers
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Meter specs tend tend to use 250v or 500 V rated parts. Exceeding these ratings by some margin may result is catastrophic failure to other parts when an arc bypasses the part.
There are 10:1 to 1000:1 probes rated to higher specs which must be observe/chosen.
Using high voltage rated resistors you can make a voltage R divider for DC and for AC use high voltage rated capacitors to make a C divider.
(not to scale) $1 rated for 6.1kV
simulate this circuit – Schematic created using CircuitLab
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If you know the resistance of the meter you can add resistance to increase the voltage range. if the meter has 1M resistance on the 1000v range adding 9 more 1000V rated 1M resistors in series would allow measurement of up-to 10KV, 2kV in would read 200V after the modification. but if you need to be safe, buy a proper high-voltage probe, don't try to build your own.
answered Oct 9, 2017 at 11:43