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motor speed controler

i have a sewing machine motor controler (wired in series with motor) that uses a"carbon pile element" where pressure on the pile causes decrease resistance and more current to flow and at some pressure point a short by passes the carbon pile

controler is rated at 95-145 volts and 0.7 amps

now someone has claimed no troubles using the controller with a 120v - 1 amp motor

is this true ? why or why not

i thought the motor , rated 1 amp, would try to draw more current than the controller was rated for and of course overheat etc

any help greatly appreciated r

Reply to
robb
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Well, it probably does, and the speed control is probably getting hotter than before. But there is a safety margin built in so it hasn't melted down just yet.

Or, just because the motor says 1 A doesn't necessarily mean it draws

1 A except under heavy load.

Has he measured the current?

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Reply to
Sam Goldwasser

that

( this mesg was crossposted and multi-posted for which i appoligize to those that care)

Thanks for help Sam

no the curent has not been measured,

the question is based on the issue of a failed original 0.5 amp rated motor being replaced with a newer 1.0 amp rated motor and wether that is such a good idea given rating on the controler.

so the original safety control seemed to be factored with a 0.5 amp motor and 0.7 amp controler ?

thanks again for reply rob

Reply to
robb

The current draw relates more to the load on the motor than the size of the motor. It will probably be fine though, just keep an eye on the temperature.

Reply to
James Sweet

the

temperature.

well that makes me wonder then because the most load the motor probably gets is at startup

because the motor has a ~1/2" diameter pully and the machine has a ~4" diameter pully (which has a heavy flywheel ). The pullies connected with a big rubber O-ring belt. Getting the machine going is a big tug on motor... then when it is going it rarely gets any load of significance as fly wheel helps drive needles through the work when resistance comes

Plus one rarely runs machine for extended periods it is usually stop and go where machine runs for 20-30 seconds stops and repeat

thanks everyone for help, rob

Reply to
robb

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