I was of the understanding that speed of a capacitor start, single phase motor was a non-starter. But a Hobby Machinist member provided this link:
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Speed control for single phase induction motors
- Thread starter DavidR8
- Start date
Single phase motor vfd's have been around for some time. They do work but you need to isolate the wiring from the capacitors and the clutch. Effectively using the windings themselves. Some motors do not bring that wiring directly out so you have to go in to the motor and bring the wires out. Also you can not reverse the motor as wired, you have to physically change the wiring, which I guess you could do with a contactor or switch, but you could never do this while powered. So an interlock would need to be installed. In industry as time is money, its more likely to put a 3 phase motor in, like 99 out of 100 times, even more. As for hobby it is completely viable. Maybe just not affordable with all the single to three phase vfd's and three phase used motors around. Now having said that, there are a lot of pieces of equipment that may have rare or even extinct motors on them and this then becomes a viable option. You may still get motor heating and harmonic issues depending on load as the motor would not be designed for vfd use.
Warning do not believe any of the wire to wire connection vfd's on some sites, they will not work. If they do work it will be for a very short amount of time. You can not connect to L1 and N and expect the motor or vfd to survive.
You take this:
And isolate the windings:
Then wire to one of these two:
Warning do not believe any of the wire to wire connection vfd's on some sites, they will not work. If they do work it will be for a very short amount of time. You can not connect to L1 and N and expect the motor or vfd to survive.
You take this:
And isolate the windings:
Then wire to one of these two:
@kevin.decelles do you think a VFD for your belt sander (3" by ... 72"?, folks I have one too) would be a useful addition? Do you find the sander too fast?
Looking at the instructions for the 2hp unit is concerning. I could be wrong but they show connection without the cap and clutch and one with. I am not sure how this would work without issues. Leaves me scratching my head. When I did the eaton dsg1 course we had a pretty big discussion about this very issue.
Correct way, that I have seen from several manufactures:
Way that makes no sense to me, they have the wiring below on the sales page but it is not in the manual. I wonder how well the vfd deals with the current before the clutch opening and the start cap being removed from the circuit.? I would not wire the one below.
The sales page - https://www.gohz.com/2-hp-single-phase-output-vfd
Manual - https://www.gohz.com/Content/Images/uploaded/GK3000-single-phase-vfd.pdf
Correct way, that I have seen from several manufactures:
Way that makes no sense to me, they have the wiring below on the sales page but it is not in the manual. I wonder how well the vfd deals with the current before the clutch opening and the start cap being removed from the circuit.? I would not wire the one below.
The sales page - https://www.gohz.com/2-hp-single-phase-output-vfd
Manual - https://www.gohz.com/Content/Images/uploaded/GK3000-single-phase-vfd.pdf