Motor swap

[strantor]

There is no ''Torque Mode'' parameter in VFDs that I'm aware of. I think the problem you were seeing with your compressor is due to the firmware in the VFD. It is not programmed to foldback and sacrifice speed to maintain constant power supplied to the motor. Quite the contrary, it is programmed to keep increasing the output power and maintain constant speed, which it will do until it faults out due to over current. You implemented the only way I know of to maintain constant power output, and that is to use an external controller. I was going to do the same thing with my compressor and realized I would need a computer in the mix to make it all work. I have never implemented that.

I didn't get a chance to tinker with the compressor this evening but I opened up the yaskawa files I was working with back then and I see why I did what I did. V1000 doesn't have torque mode so I basically had to roll my own. V1000 is the entry level Yaskawa; higher models do have torque mode. And of course GS2 doesn't have it because that's an even more dumbed down drive than V1000. Other high end drives also have torque mode (officially "torque control" mode) - Toshiba AS3 (ref manual E6582106), Parker 690+, 890 drives, AC30, AC10, Some Lenze drives I believe, and some SEW (Movitrac I think?) drives I have seen running torque control applications.

Anyway, I've attached a snapshot of my constant HP program from the onboard Yaskawa onboard PLC in case you ever rekindle the idea of the constant HP compressor. You could probably do this in AD/Delta GS4/GS20 onboard PLC.

 

[Firebrick43]

Aha! That's a very good point. And the answer is no. I've never intentionally run any 60 hz motor below 40 hz. Someone somewhere with some authority had told me it was bad practice.
Now we're talking about 0-200 hz motors with 6k rpm. I'm downright flummoxed by the proposition. But thank you for all this information everyone. It'll take me some time to calm my nerves enough to let it soak in. Lol

You can run regular motors down to 20 hz without issues unless you are dogging them (heat issues). Go below this and the way a vfd works the voltage spikes will blow holes in the insulation of standard motors. Inverter rated motors and servos have H class insulation to deal with this and therefore run at very low speeds.