Discharging a capacitor

[sako243]

Got to be careful that it can take the load (hence my suggestion of a huge wirewound resistor).

Doesn't matter if it's a high value resistor as I stated. A 1M resistor at 400kV will only pull 400mA, somehow I know that a single phase capacitor won't be charged up to 400kV.

Edit: bear in mind that for a 220uF cap a 1M resistor will discharge ~1/3rd of the voltage in 220s. T=RC.

 

[Turbo]

Part of my job as a maintenance engineer at a factory was to test the power factor correction capacitors in the switch panel in the plant room. Quite a simple task, disconnect them with a switch, connect a multi-meter, wait until the voltage was zero then test them with a capacitance meter. These things were huge, not to be messed with but if you followed the procedure it was a simple, safe task! Whole thing took around 2 hours so it was a cushy job on a Saturday morning at double time!

Not so for the previous guy that was given the task. Always thought he knew everything & not known for his patience he didn't wait for the voltage to drain completely before connecting a very expensive fluke capacitance meter. The result was a huge bang, one ruined meter & a clean pair of boxer shorts needed!

I got a nice new capacitance meter when I started & when the factory closed it followed me home!