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Fridge compressor probs...

I picked up a small fridge compressor with the idea of playing around using it for a SMD vacuum parts pick up tool, but it behaves strangely.

On initial power up it runs fine, very quietly. It quickly/easily pulls down to 20kpa (-80kPa).

However if I disconnect the power and reconnect there is a quiet hum but the motor is stalled. If I disconnect again then wait a minute or two before reconnecting it powers on fine and will run fine - I've let it run for 5 minutes continuously with no problems.

As part of the terminals to the motor there appears to be a thermal overload switch, it gets warm but not hot (guess ~30 Celius)

Heres a link to the data sheet:

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I vaguely recall something about fridges having protection against rapid cycling of the power for some reason - but that could be rubbish.

Any ideas?

PS: neat home SMD vac pickup video:

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Reply to
Dennis
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When used in a fridge as designed if the power is removed then reapplied quickly, the pressure of the gas will cause the motor to stall. By waiting for a period of time for the pressure to disperse into the pipework, the compressor will restart. this usually takes a few minutes.

The thermal overload device on the input terminals will sense when the motor is stalled and results in the compressor cycling on for a short time (about 20-30 seconds), then goes off for about 3-5 minutes. Eventually the compressor will overcome the gas pressure and restart normally.

Reply to
Art Vanderlay

Thanks for the reply Art. Yep, I found a PTC thermistor under a cover on the compressor. Google led me to more infor on how it works.

Now to play with making my SMD pickup.....

Thanks.

Reply to
Dennis

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