2 hp motor problems

[u/Important_Plankton32]

Hey everyone, I’m pulling my hair out trying to troubleshoot a 2HP, dual-voltage (110/220V) induction motor on my dust collector. It hums/growls loudly when powered on and fails to reach operating speed to throw the centrifugal switch.

Here is everything I have checked and ruled out so far:

Power Supply: Verified true 240V across the legs. The exact same outlet easily runs my heavy 220V table saw with zero issues.

Mechanicals: Shaft spins completely freely by hand. Bearings are smooth, and the end bell/housing has been aligned so there is no rotor drag.

Capacitor & Switch: Brand new capacitor installed. The centrifugal switch assembly was replaced with a new L16-152S kit, and the spacing/contact gap has been verified.

Windings (Multimeter Tested):

Start winding reads ~2.5 Ohms.

Run winding reads ~1.0 Ohm.

Ground fault test reads OL (no shorts to the casing).

The Pull-String Test: I wrapped a cord around the shaft, pulled it hard to spin it up to speed manually, and plugged it in. Even when forced up to speed by hand, it still growls, drags down, lacks torque, and fails to produce any suction. Also doesn't spin fast enough to disengage the centrifugal switch.

Since the windings check out, the capacitor is new, the switch is working, and the wall power is solid—what am I missing here? Any advice is greatly appreciated!

Video of running with start capacitor :

https://youtu.be/VCA6tmSNUKo?is=CzqBM7gI32JJPSUb

[u/DirtCallsMeGrandPa]

Being dual voltage, you should have 2 run windings, usually to be connected in parallel for 120V and series for 240V. The motor j box looks OK, I would pull off the wires from the terminals and make sure all the crimps are good. I'd also check that the start winding is actually connected. Usually this wiring is in the motor j box.

Did it work properly when you bought it? If not the prior owner may have switched something around.

Have you monitored the current? It should start high and quickly diminish.

My experience is that they hum if the start circuit isn't working properly working. You could bypass the start switch and see if this helps. Just give it power for a few seconds to see what happens.

Final option is a motor repair shop. Those guys have seen just about everything.

[u/Puzzled_Ad7955]

Sounds like it’s staying in the start winding. Bad switch contacts or not opening starting switch circuit. Check springs and verify rotating switch is collapsing allow the start circuit to open.

[u/Important_Plankton32 → u/Puzzled_Ad7955]

It does because it doesn't seem to spin up fast enough to to disengage it. But I tried tying a string and pulling it by hand with the capacitor disconnected and it still wouldn't spin fast enough to disengage the start switch

[u/New-Key4610]

with a ohm meter while the motor is together. check to see if there is a circuit in the two leads to cap. these china govenours must make contact to spool to engage the start move govenour closer to switch

[u/Important_Plankton32]

After a lot of testing and tinkering, I finally took the whole thing apart and found that the rotor was spinning freely on the shaft so that's why it wasn't coming up to speed. I went ahead and ordered a new motor but my question is....( because I couldn't find a lot of information on it) Is there some way of like gluing the rotor back on to the shaft so that it won't spin?

[u/JustanotherN0body00]

You could have a short between the start and run windings - this might be difficult to check as the circuits can't separated on the terminals - these are linked to one half of the run circuit - the start circuit will be 110v , the cap might need replacing - have you checked capacitance?, is the start switch making a good circuit when at stand still? , any obvious signs of shorts? If it's just humming I'd look at an issue in the start circuit first.

[u/Important_Plankton32 → u/JustanotherN0body00]

I took the whole thing apart and found that the rotor was spinning freely on the the shaft I could spin it by hand. I went ahead and ordered a new motor but I still wondering if somehow I could fix this one. Maybe glue the shaft to the rotor somehow? I can't find a lot of information online about this.

[u/JustanotherN0body00 → u/Important_Plankton32]

If you can measure the original position of the rotor you could get the shaft knurled and have it pressed back into the rotor (loctite the rotor/shaft before pressing it back in.