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Old 09-17-2017, 10:33 AM
Findm-Keepm's Avatar
Findm-Keepm Findm-Keepm is offline
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Join Date: Jun 2007
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Quote:
Originally Posted by madlabs View Post
If you want to be real careful, put a 1 Mohm resistor in series to ground. Prevents big sparks/currents and is easier on caps when discharging them.
With some large (100uF) capacitors, the R-C discharge time with a 1 Megohm resistor could be over a minute.

Pomona Electronics made a 40KV discharge set (lucite handle, cooper bronze shank with swappable probe, hook, and balled ends) for the Navy - they used a 5K series resistor. That kept the RC time for discharge under 6 seconds for just about everything. Not sure of the composition/wattage of the resistor, but we had to megger it as a daily test. Me, I'd use a 2 Watt Carbon Comp in series, say 5100 or 5600 ohms, standard values.

450V discharging through a 5K resistor to ground keeps it under 100mA at all times on the discharge curve - no sparky-sparky at all.

Or, if you want to visually see the discharge effects, build one of these:

http://jestineyong.com/build-your-ow...scharge-probe/

Has LEDs that indicate if there is still voltage present.
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Last edited by Findm-Keepm; 09-17-2017 at 10:39 AM. Reason: Added link/info
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