motor speed controler

[robb]

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

 

[Sam Goldwasser]

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

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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[robb]

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?

( 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

 

[James Sweet]

( 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

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.

 

[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.

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