Single phase motor reverse rotation

[waigy]

Will a smaller capacitor make it start more gently or is there a better way of making it gradually speed up?
I was using a bench grinder before which gradually speeds up but it didn't have enough power at 450 watts for polishing.
This motor is much more powerful at 2hp but it gets up to full speed instantly.

 

[westward10]

If it is correctly connected reversing it will have no effect on its performance.

 

[waigy]

I had to reverse the rotation to get my buffing wheel spinning in the right direction and it's working fine, but I would like it to start up gradually if possible.
Could I add a knob that adjusts the speed or similar?
I have one of those kicking about for adjusting the cooling fan speed on a car amplifier.

 

[westward10]

To confirm are you spinning it by hand to get reverse motion.

 

[waigy]

No, it spins in reverse direction by itself after I swapped those two wires.
I just double checked it with the buffing wheel off the shaft.
When I start the motor it now spins in the direction I want it to but when I bought the motor it spun the wrong way.
I've swapped those wires a few times as I blew a few fuses so tried putting it back the way it was before to see if that was the problem.
Every time I swap those wires it spins in the opposite direction.
Since I slackened the casing bolts a touch it has worked no problem in the direction I want.

 

[Lucien Nunes]

I hear your comment that it is starting in the correct direction, however interchanging two leads that are connected together by the copper link won't change anything, as they are both still connected to the same place electrically speaking. You might have actually altered something else too.

A smaller capacitor can reduce starting torque. If there are two in parallel, maybe disconnect one. However, this will alter voltages and currents and I can't say what will be out of spec - the capacitor voltage might be higher than intended - and can't really recommend random experiments on a forum. More conventional methods of taming a start would be an autotransformer or resistance.

Whatever method, it's important that the motor starts promptly so that the centrifugal switch cuts the start winding out of circuit within the rated operation time of the capacitors (which will fail catastrophically if lefft energised for too long).

 

[waigy]

Are you sure this motor has a centrifugal switch as I can't remember seeing one when I took it apart to change the bearings.
It doesn't have one of those switches that acts like brakes when the motor has been switched off.

 

[westward10]

It looks like a two value capacitor motor or capacitor start and capacitor run motor. Some means of switching, normally centrifugal opens to take the start winding out of circuit.

 

[waigy]

I thought these motors has a start and run capacitor but I've checked the website and it says some have start and run capacitors and some have capacitor start and induction run.
I can live with it the way it is just now by hand spinning the wheel just before starting.

 

[telectrix]

what you need is a variac. you start it on a lower voltage then increase as it spins up. like here, but a 240V one.

View: https://www.youtube.com/watch?v=AEyPBFOhhHw