Can moters be run slower with less voltage (brush types)

I heard power tools run on long cords go bad sooner. I assume because of the voltage drop the motor runs slower. I am thinking that the voltage drop is not a direct factor but slower speeds means less airflow since they all have a fan on the shaft (except pass through vacuums unless heavy duty. I remember in the seventies sears had a vacuum that had two speeds. But I think it was controlled by the entry point of the wire in motor, not a device that is like a dimmer made for brush motors. I saw one on a centrifuge and after market for routers.

I am asking if lack of air flow from lower speeds due to voltage drops damage power tools (skilsaw and such)

Reply to
davidlaska
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I wouldn't put much stock in it, but shorter, heavier cords are a good idea. I'd be more concerned about low voltage at the outlets. Maybe your tools are just cheap?

Reply to
Homer J Simpson

I only hear about power tools like skill saws can be damaged. Never had a tool go bad. I thought these motors can run at any speed if cool.

Reply to
davidlaska

I forgot to say that cheap tools do break quick, stuff from China, I am not blaming them though, they deliver what the market will take.

What I thinks I am really asking is a long cord voltage drop similar to after-market devices that slow down motors like a router?

Reply to
davidlaska

Similar, you're limiting the current though rather than effectively using PWM so you'll get less torque with voltage drop than with a speed controller, the motor shouldn't heat up more than usual though.

Induction motors on the other hand will overheat if the voltage drops. They're constant power devices and lower voltage will cause higher current to be drawn to compensate, higher current = more heat.

Reply to
James Sweet

Dont believe everything. The only motors so affected are induction motors, which are at times found in stationary tools but not hand helds.

Reducing V reduces both power diss and airflow, and temp stays roughly constant over a wide speed range.

NT

Reply to
meow2222

Thankyou: it is popular among carpenters but they can continue thinking that and get the large cords.

Reply to
davidlaska

Thankyou: it is popular among carpenters but they can continue thinking that and get the large cords. I do not want to explain it unless asked.

Reply to
davidlaska

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