Best way control motor rpm...

[kpp]

HI,
I'm looking for help in determining what I need for the control winding circuit of this motor:

http://www.surpluscenter.com/item.asp?UID=2008042315303006&catname=&qty=1&item=5-1105

I'm trying to keep this setup as small as I can and cost is a factor also.

I have been using a small gear-motor vac with a fixed rpm of 80 for use as a hot liquid mixer. It overheats after about 15 minutes - probably since its not rated for continuous duty. I was able to add a low voltage cooling fan & heat-sink to solve that problem.

With all that added, the case is getting larger, and since I now see the need for an adjustable rpms - looking a for a new solution.

Guidance or input is appreciated....

Kevin

 

[bklauba]

Tough to control the speed of a single phase induction motor; typically more trouble than it's worth. Think either DC and a simple variable voltage drive, or 3 phase and a VFD. You don't have to have 3 phase to feed the VFD, especially in the size range you are looking, you can get a VFD that takes 120 VAC s.p. in, 3 phase out. Check out KB Electronics, they make both simple DC drives and modestly priced VFD's. There are plenty of DC and 3 phase motor/gearheads available surplus.

BK

 

[BobM3]

The catalog page says you need a 10 VAC control signal. I'd think the easiest way would be to use resistors across the 110 VAC to create a voltage divider. One of the resistors would be variable.

 

[jraef]

Or get a small transformer to drop the 110V to 10V, then put a potentiometer on the 10V signal.

Can't tell what that motor really is though. I would suspect that the motor itself is just a capacitor start 1 phase motor (hence the need for an external cap)> So the 0-10VAC speed control signal is maybe going to an eddy current or magnetic clutch drive perhaps? Hard to tell with surplus stuff like that.

 

[SteveWag]

There is a tab on the sale site page showing the wiring diagram. Looks strange to me. It shows the capacitor is series with one 120 VAC line, and then shows the motor reversed just by putting the cap in the other leg-strange to me.
Steve

 

[itsmoked]

Yep pretty strange. Maybe it's like a SloSyn synchronous motor. I don't see how the speed is going to be varied either.

But at $18?? Doesn't work no loss.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[waross]

I wonder if one line is common to both the 120 volt windings and the 10 volt winding. That would explain the connections. Yes, I know that it doesn't show it specifically, but most motors that reverse by changing the capacitor from one line to the other have two windings and one common line.
I'd check for continuity between the main leads and the control leads. If one line is common then possibly the motor is running with the main windings in series with the clutch/control winding. That would explain how it could work now with no 10 volt supply.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[kpp]

Thanks for the feedback. I'm going to order one and see what
can be done with it. As was mentioned, it won't break the bank if it doesn't work...

Kevin

 

[roydm]

Like most others I can't figure out how this is works.
I don't know that a simple voltage divider setup will suffice. The control input may be low impedance in which case you may need something to boost the current, a pair of transistors perhaps.
I wonder if a stepper motor would be simpler, you should be able to run one of those at whatever speed, you don't give the torque requirement.
Roy

 

[ScottyUK]

I have a suspicion that this motor is simpler than it seems and that the auxiliary winding is either providing a boost to the main winding flux or is bucking it to weaken the flux. This would give speed variation on a fan or similar application.


----------------------------------

If we learn from our mistakes I'm getting a great education!

 

[itsmoked]

Or it is saturating the magnetic circuit like a constant voltage resonate supply,(Sola). The cap would prevent ultimate meltdown.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[ScottyUK]

Will be interesting to see what happens once the OP gets one of these to play with. If it wasn't going to cost me a fortune in shipping I'd be curious myself.


----------------------------------

If we learn from our mistakes I'm getting a great education!

 

[everythingworks]

This may explain the rotation of reversal.

 

[bklauba]

Is this the same motor? Markings ID it as a DC motor, with input voltage requirement of 20 - 29 VDC.

BK

 

[waross]

The original post described an AC motor.
The last picture shows a DC motor.
The link on the original motor shows a capacitor in series with one of the leads. (Go to the link and then click the wiring tab.) A DC motor won't work with a capacitor in series with one of the leads.


Bill
--------------------
"Why not the best?"
Jimmy Carter