Compressor motors?

[BrazosJake]

Question for some of you electrical types: What's the difference between a "compressor" motor and just an everyday induction motor? I see HF has their 2HP compressor motor on sale again, and just wondering what it might be good for, I know it could be used to drive a DC, but how about a bandsaw?

Thanks from a motor ignoramous:-)

[Thom2]

I'd be curious to hear the 'official' answer to this as well. The best 'guess' that I've been able to come up with is that the motors I see listed as compressor motors turn at 3450rpm instead of 1725. I just always assumed that was the difference between the two.

Thom
curious in PA

[sscherin]

Well according to the Baldor site General Pourpse is a compressor motor.

Looking at the HF offerings I noticed almost all the "Compressor" motors have start and run caps.. The GP motors only have start caps.

[LarryG]

I don't think RPM has anything to do with it, as I'm pretty sure I've seen compressor motors that run at both speeds.

I always thought "compressor duty" meant that the motor had sufficient start-up torque to overcome the resistance of the compressor unit itself. I would think that would be a somewhat more difficult chore than, say, spinning the wheels on a bandsaw.

[don_hart]

In general compressor motors should be called compressor duty motors. This means the unit is not designed for contious duty but for intermittant duty for such uses as you guessed it compressors. Most of these motors are designed fopr 50% duty cycle meaning the run and rest the same amount of time.

[BrazosJake]

quote:Originally posted by don_hart

In general compressor motors should be called compressor duty motors. This means the unit is not designed for contious duty but for intermittant duty for such uses as you guessed it compressors. Most of these motors are designed fopr 50% duty cycle meaning the run and rest the same amount of time.

Thanks Don. I suspected that was the case, as I see Leeson makes both and the compressor-duty motors seem to be priced about 1/2 of what the same HP/RPM regular motors cost.

[messmaker]

Who has put this motor on a tablesaw for the 1/2 hp bump? Pretty cheap upgrade. A lot of blades cost that much.

[dedaddy]

Compressor duty motors have greater starting torque needed to get a compressor started. That is why it has both a start and a run capacitor. The start capacitor is bigger than the run capacitor and gives the motor greater torque at low speeds when starting. But it really kills efficiency at running speed. Thus a smaller capacitor is used once it is running.

A fan load usually does not require the start capacitor since there is almost no load at low speeds.