Fridge compressor probs...

[Dennis]

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:


http://www.transtech-co.jp/electronics/en/Library/compressor7.pdf

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:
http://www.youtube.com/user/mikeselectricstuff#p/u/8/pdGSFc7VjBE

 

[Art Vanderlay]

On 25/09/2011 3:45 PM, Dennis wrote:

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:


http://www.transtech-co.jp/electronics/en/Library/compressor7.pdf

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:
http://www.youtube.com/user/mikeselectricstuff#p/u/8/pdGSFc7VjBE


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.

 

[Dennis]

"Art Vanderlay" <nospam@thank.you.very.much> wrote in message
news:j5p2m8$dmo$1@dont-email.me...

On 25/09/2011 3:45 PM, Dennis wrote:
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:


http://www.transtech-co.jp/electronics/en/Library/compressor7.pdf

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:
http://www.youtube.com/user/mikeselectricstuff#p/u/8/pdGSFc7VjBE


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.

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.