Dust Collector

[Little Bill]

Had a guy call me and asked if I could help see why his dust collector wouldn't run. I have not been there to see the unit, I've only talked and listened on the phone. From his info, it is a 240V single phase motor. He said it had push button switches. He said there was a box mounted beside the motor. I can only assume it's part of the control circuit.
When he pushes the start button, the motor just hums. I could hear it on the phone and it sounded like a 3Ph motor that had lost a phase trying to start.
I'm going to look at it but wanted some ideas as to what to look for. I'm guessing it might have a contactor that isn't pulling in, or maybe a capacitor that has blown.
So I'm looking for ideas as to what to look for.

 

[Joethemechanic]

Starting capacitor or start switch. Maybe if someone had their fingers into it, something connected wrong

 

[VirutalElectrician]

A lot of shop people will pick up used 3ph equipment and use a phase converter in their home shop. Maybe that's what is going on here?

A dust collector motor maybe gummed up with years of dust and needs a good cleaning or replacement?

 

[hillbilly1]

Starting capacitor or start switch. Maybe if someone had their fingers into it, something connected wrong

Yeah, most likely the starting capacitor.

 

[Little Bill]

A lot of shop people will pick up used 3ph equipment and use a phase converter in their home shop. Maybe that's what is going on here?

A dust collector motor maybe gummed up with years of dust and needs a good cleaning or replacement?

He does not have a phase converter. The dust collector is a complete unit, so nothing added to it.

 

[Joethemechanic]

It is most likely this capacitor start/ capacitor run



But it could also be this with just a capacitor start



Not really much to either circuit

 

[Joethemechanic]

And to reverse rotation you just swap leads on the main winding or the start, whatever is easier

 

[Little Bill]

Well I went to check the motor. I took the cover off the capacitors. I didn't even have to get my meter out since it was very obvious as to the problem. The start capacitor was disintegrated, and the run capacitor was bulging with the "goo" running out of it.

 

[Little Bill]

I just noticed the start capacitor says 125V, and the run cap says 250V. Why would these be different voltages?

 

[gadfly56]

I just noticed the start capacitor says 125V, and the run cap says 250V. Why would these be different voltages?

Ooopsie at the factory?

 

[Little Bill]

Ooopsie at the factory?

Maybe, but I wonder how it lasted so long?

 

[Joethemechanic]

I think as part of an L-C curcuit the capacitir never sees full line voltage. I'm not sure though, that class was like 50 years ago.

But the start only operates briefly. They are a non-polarized aluminum electrolytic capacitor

 

[augie47]

Looks like he may have had a visit from mr. lightning,
Also I would make sure and blow our the motor and controller. Dust collectors are notorious for dusty contacts,

 

[Little Bill]

I wonder if the centrifugal switch might need checking? Like maybe it isn't opening after the motor starts.

 

[augie47]

I wonder if the centrifugal switch might need checking? Like maybe it isn't opening after the motor starts.

That was my thinking about the dust, I've seen a lot of motors where the switch isn't working properly due to dust/dirt build up.

 

[Little Bill]

Another question. When replacing the capacitor, should I use the same MFD as the blown one since the wrong voltage cap was used? In other terms, 400 MFD 250V replacing 400 MFD 125V.

 

[Joethemechanic]

Start capacitors don't last long if left in the circuit

 

[Joethemechanic]

Another question. When replacing the capacitor, should I use the same MFD as the blown one since the wrong voltage cap was used? In other terms, 400 MFD 250V replacing 400 MFD 125V.

The start can be a lot bigger and not hurt anything, but the run should be close, but bigger is ok if it's not a lot maybe 125 or 150 percent larger

 

[Little Bill]

Thanks!

 

[MTW]

Another question. When replacing the capacitor, should I use the same MFD as the blown one since the wrong voltage cap was used? In other terms, 400 MFD 250V replacing 400 MFD 125V.

Increasing the voltage ratings can only help longevity. As to the MFD rating the run cap should keep the same MFD range. The start cap can be varied a bit as they come with larger range sizes from the capacitor manufacturers as standard. But the run unit is sized by the motor manufacturer for best efficiency and power factor.

Take the existing caps with you to obtain replacements, as higher voltage or MFD valued units may not fit in the capacitor covers on the motor. Even the replacement brand can affect the physical size. North American physical sizes can differ between Asian and European manufacturers. It's not a good thing when you have a replacement that doesn't fit in the cover or rattles around loose inside.