Electronics > Projects, Designs, and Technical Stuff
Faster capacitor bank bleeder
jmelson:
--- Quote from: Circlotron on March 06, 2019, 11:39:27 pm ---A 1000W 240v radiator bar is 60 ohms so two in series will have a time constant of 0.576 sec. All done in under 3 seconds. An SCR might be a better choice than a relay because of no contact bounce and consequent arcing.
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If power is just blipped, the SCR could stay on, and set things on fire. Also, you need a circuit to detect power loss and turn on the SCR. The arcing issue should be limited on contact closure, and the cap bank should be at near zero voltage when the relay is energized and the contacts open.
Jon
jmelson:
--- Quote from: OM222O on March 07, 2019, 12:11:58 am ---simplest and safest way: use a constant current DC load, fairly cheap and simple to build.
Use an IGBT with suitable high voltage rating, any basic rail to rail op amp (I've had good results with MCP6002) and high power resistors.
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NEVER use an IGBT in the linear mode, they are specifically built to not tolerate that. In the linear mode, the current hogs to the warmest part of the die, due to the negative temperature coefficient of Vce. Even very small currents relative to the max collector current rating will destroy them, when not saturated hard.
Jon
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