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Registered Member #1403
Joined: Tue Mar 18 2008, 06:05PM
Location: Denmark, Odense C
Posts: 1968
Graham Armitage wrote ...
Antonio wrote ...
Put LEDs in series with the bleeding resistors. You can then see if it's safe to touch the circuit and if it is working correctly.
That's a great suggestion. Thanks
Take a sound advise from heavy industry, if you use light off for safe state, use two separate lamps in parallel, you do not want to think your circuit is safe just because a lamp failed.
This is why normal state of signalling lamps offshore is light always on and unsafe is light blinking.
Registered Member #30
Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706
I prefer neon lamps, they look more ominous than LEDs.
I wouldn't put things in series with the bleeder resistors either. If one of the LEDs comes loose, not only do you lose the high voltage warning, but you lose the bleeder resistor and the high voltage lurks around for longer.
I also spent some time thinking about the issue Mads mentioned. My solution was to add an analog voltmeter permanently wired to the DC bus. It serves as a backup to the warning lamps and also does something useful in its own right.
Registered Member #3324
Joined: Sun Oct 17 2010, 06:57PM
Location:
Posts: 1276
I would personally not have 5 minutes as im impatient. I would suggest a 10 second discharge though a high wattage resistor, not long enough to damage it. Use a contactor that is Normally Closed so when the circuit is not being powered from the socket, its being dumped and the resistor isn't connected when its being used, saving a tiny amount of electricity.
Registered Member #6038
Joined: Mon Aug 06 2012, 11:31AM
Location: Salado, TX
Posts: 248
Seems to be two threads in one here - one around the visual aspect and the other around the actual discharge. I tend to be impatient too and 5 mins would probably not work for me. I did have a relay that was normally closed with high wattage resistors and they would rapidly bleed the caps when power was turned off. That worked great until a strike to the primary fried it (they are not cheap). i don't mind a steady trickle bleed while in operation if I know it will passively start dropping the voltage as soon as I power down.
As Steve suggests, it's not good to have anything in series with the bleeder resistor, would this circuit work as an indicator? 2 LEDs for extra safety.
Ooops - LED's won't light up if they're wired that way. This should be better...
Registered Member #230
Joined: Tue Feb 21 2006, 08:01PM
Location: Gracefield lower Hutt
Posts: 284
no!! that circuit seems to be random components put down on paper. for a start the DC rail should be + and minus not neutral. The capacitor stops all dc from flowing so no leds will light. the leds are in backwards. There is no need for the diode in fact its inclusion will make sure the leds will not light I'm susre there are still more mistakes
Registered Member #6038
Joined: Mon Aug 06 2012, 11:31AM
Location: Salado, TX
Posts: 248
Correct - will not work. I realized after posting - I pulled it from another circuit, but that was an AC source in which case I believe it does work. Scratch that for the rectified DC supply.
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