bleed resistor across start cap
bleed resistor across start cap
(OP)
Can you think of any reason other than personnel safety for a bleed resistor across a starting cap on a single phase motor. If you tell me it protects the relay contacts, show me why.





RE: bleed resistor across start cap
Why would getting into the capacitors be considered a routine procedure anyway? It probably takes 10 minutes or more to get that deep into the motor, and it's not a typical procedure done at the motor, it's usually done on a workbench after removing the motor.
Eng-Tips: Help for your job, not for your homework Read FAQ731-376
RE: bleed resistor across start cap
RE: bleed resistor across start cap
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RE: bleed resistor across start cap
RE: bleed resistor across start cap
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: bleed resistor across start cap
Eng-Tips: Help for your job, not for your homework Read FAQ731-376
RE: bleed resistor across start cap
I have never seen a starting capacitor with a bleed resistor. The resistance of the starting winding is very low in relation to a discharge resistor.
I have used small individual capacitors for power factor correction and they do have a bleed resistor.
RE: bleed resistor across start cap
RE: bleed resistor across start cap
RE: bleed resistor across start cap
RE: bleed resistor across start cap
RE: bleed resistor across start cap
RE: bleed resistor across start cap
The capacitors stored DC charge energizing the start winding, as the motor slows and the switch closes, is what can brake a motor. Not the resistor.
RE: bleed resistor across start cap
RE: bleed resistor across start cap
resistor (other than safety) is that the potential
across the capacitor would be double, if it was
switched in when the line was at the opposite
polarity from the stored charge. How often this
would occur with conventional centrifigal switches
or relays is problematic - there are zero-crossing
SSR's and other methods of controlling switching
timing, but these would be a bit more expensive
than a resistor, methinks.
<als>
RE: bleed resistor across start cap
The problem with this is that since the cap is in series with the secondary coil you have an L-C series circuit and so you don't get a surge discharge but a slow measured discharge.
So far I don't see any valid answer to my original post. but I thank you for all your input.