"auto boost" and "torque boost"difference in AC Induction Mo

[ecenus]

What is difference between "auto boost" and "torque boost" during AC Induction motor start? If the motor has no load, is that possible to make the motor work at low speed range, say under 10hz?

Thanks!

 

[jraef]

Assuming you mean under the control of a VFD? Assuming you mean a 3 phase motor? What to you mean by "make it work" if there is no load? Spinning with ZERO load cannot be called "work" in my book. Please give the whole story; what are you trying to do and what do you have to work with?

 

[ecenus]

Yes, I am using VFD, 3 phase AC Induction motor. Spin the motor with no load first.

I actually want to understand more about the motor starting process which has "auto boost" and "voltage boost".

thanks!

 

[Skogsgurra]

Is it "weak" torque at low speed or reduced cooling that is your concern?

Many (most) vector control schemes overcome the problem with low torque at low frequencies. It is only when you have a scalar system (constant V/Hz) that you have a problem with frequencies below about five Hz. And that's why you add some boost to compensate for resistive voltage drop in the motor windings.

I do no know what "auto boost" is. Perhaps some manufacturer's trade name for slip compensation? Also only used in scalar controls. The latter is not used much these days.

Reduced cooling is sometimes a problem also when there is no load on the shaft. Especially with motors with high magnetizing current. But, usually motors can run unloaded at low speed without problems.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[gepman]

Some of the VFD parameters names mean different things to different manufacturers. If you want someone in this forum to interpret the meaning of the VFD parameter for you then you at least need to give the make and model number of the VFD, the parameter number, parameter name, and to be nice, cut and paste the actual description out of the VFD user's manual.

Even then the user's manual isn't always fully descriptive of how the drive software implements this particular VFD feature, especially on the more obscure parameters. Then you need to contact the manufacturer's representative in order to get a more detailed explanation.