Guru
Joined: 26/07/2007
Location: AustraliaPosts: 1686
| Posted: 01:49am 15 Oct 2009 |
Gizmo, I think this bit needs some modification:
[quote] Please note, the capacitors in these circuits can store a lethal charge. If the windmill is run without a load, even if just for a few seconds, the capacitors will charge to several hundred volts. Even if the windmill has stoped, the capacitor charge will remain and must be considered lethal. In all circuits I've added a bleed resistor ( R* ) across the rectifier outputs. This should be a 10k 5 watt resistor. A better option is to add a resistor across each capacitor, use a 100k 1watt resistor. When performing any maintenance on a capacitor modified alternator, please remember to test for any stored voltage with a multimeter before touching any connectors. Even with the bleed resistors, it would be worth while using a 47ohm resistors and shorting clips across the capacitors, just to be sure. [/quote]
It is a good warning, but following the instructions [quote] A better option is to add a resistor across each capacitor, [/quote] will result in destroyed back to back capacitors.
Nothing must be allowed to touch the intermediate terminal between back to back caps. The R will destroy the assymetric leakage current.... which protects the oxide layer.
A resistor can go across a capacitor pair in the dc back to back system, but not across each capacitor..... there is a cap thread somewhere you can read if you have a few hours... it's all in there.
It must be mentioned, that a bleeder across a back to back pair will result in no potential left across the pair ( it will bleed off to zero), but full potential will remain across one of them until the leakage bleeds it away.... so some physical mechanism needs to be in place to make it impossible to get to the middle terminal as it will be alive.... but as a unit it will be benign with a normal bleeder as would any AC capacitor with a bleeder resistor..... they must be treated as a unit only, not individual caps.
..........oztules
Village idiot...or... just another hack out of his depth