Thread: Polisher/sander acts as if three phase motor controlled by VFD.

Polisher/sander acts as if three phase motor controlled by VFD.

Probably isn't, but it's behavior is intriguing:

Soft start, with variable speed thumbwheel. 1000 RPM to 3000 RPM.

Doesn't slow down when I increase pressure on the disc, though it will trip out on extreme loads.

The brand is GMC, "Global Machinery Company", a quasi-house-brand of Lowe's several years ago. Company based in Australia, tool made in China.

Model CSP711UL, 11 amps. No patents declared.

Can this behavior be replicated without a three phase motor, without a VFD drive?

It does have external brushes, so that negates three phase, eh?

Just wondering,
Steve

Universal (brushed AC/DC) motors, are easily speed controlled . No need for fancy electronics.. Maybe a small SCR circuit to help with soft start, low end torque..

Almost every decent hand drill made in the last 30 years has VS standard..

Such motors can cost more to make than an equal size 3 phase, and have wear parts (brushes and commutor). Most people do not have 3 phase at the wall, so a very popular item for home equipment.

But it might have a VFD and you don't realize it. A number of OEMs have taken to using little PCB mounted VFDs in their machines now, they take in 120V single phase and put out 230V 3 phase to a 3 phase motor. It might just look like some innocuous box to you, some even build them into the motor itself. I bought a new "energy efficient" washer and dryer, they have them now, I can hear them when it's running.

[QUOTE=S_W_Bausch;1822943It does have external brushes, so that negates three phase, eh?
Steve[/QUOTE]

yep. universal motor. see abarnsley reply