Products > Test Equipment

Can you use low impedance volt measurement to discharge capacitors

(1/1)

Skippy:
Just watched Dave's Agilent multimeter review. I see it's got a low impedance volt measurement input.

Could you use it to discharge  filter capacitors in power supplies? So, you've got 300V in your cap, you attach the probes, it's got 10k impedance across it, and you can watch the power drain out? Or would your multimeter melt? Or am I a numpty in some other way?

Excavatoree:
In SOME cases, you might get away with it,  but honestly, why risk an expensive meter when a cheap resistor (chosen correctly) is the best way to do it?

alm:
The low impedance mode is not very resistive at high voltages. The Agilent U1272/1273A, for example, is specified as having a 2 kohm input impedance in lowZ mode on the 1000 V range. 1000 V across 2 kohm would dissipate 500 W, not going to happen. So there is something like a PTC in series that goes up in resistance as the current through it increases. It is designed to discharge the stray capacitance of wiring, I would not rely on it dissipating the energy from a large cap. It might very well go high resistance and stop discharging the cap.

ddavidebor:

--- Quote from: Excavatoree on April 11, 2013, 01:36:10 pm ---In SOME cases, you might get away with it,  but honestly, why risk an expensive meter when a cheap resistor (chosen correctly) is the best way to do it?

--- End quote ---
+1

Navigation

[0] Message Index

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod