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Thread: Start capacitor, how to wire?
06-26-2009, 06:14 AM #1
Start capacitor, how to wire?
Oddly enough I've never had to do this. I just got a little motor for a project and it has no capacitor; stumped me for a moment why it would only run when I spun it up
Data plate info:
220v .25A 50hz 1250rpm with 4uF listed. I can dredge up a cap, just need to know where to put what wire.
the black is the same gage but with much thinner insulation. I hooked the blue and brown (usual hot and neutral colors here) to 220v and she ran when spun.
No way to see what the wires do in the motor as they disappear into the windings.
06-26-2009, 06:38 AM #2
The start cap goes in series with the start winding. If your motor as a start switch on the rotor with a pair of contacts that are closed when the motor is at rest, take 1 of those wires off the contact and put it on the cap, then wire the other side of the cap back to that contact.
06-26-2009, 07:41 AM #3
I'm not sure what you see is a starting capacitor but a phase shifting capacitor, which is common on single phase induction motors. Sometimes called "Run capacitor". This capacitor provide the auxiliary winding a 90 deg. shifted current. Look here: http://www.allaboutcircuits.com/vol_2/chpt_13/9.html for the "Permanent-split capacitor motor"
Use ohm-meter to messure the resistance between all the wires and note it here.
06-26-2009, 07:59 AM #4
06-26-2009, 08:10 PM #5
Well, its EUROPEAN...... that explains the colors totally...... so the black wire is the capacitor.
use your ohmmeter.
Find the wire to which the black has the lowest resistance..... that is the common, and the cap should go from black to the other one.
06-26-2009, 11:04 PM #6
Don't be mis-lead by the terminology. Start capacitors are used to phase shift
the current in relation to the voltage for a brief period of time to get the rotor
inside the motor to turn. Then it is switched out. If you can substitute a oil
filled capacitor for you motor you will probably never have to worry about the
capacitor wearing out again.
06-27-2009, 04:47 AM #7
That looks like a cap run motor as Avivz suggests: I can't see the centrifugal switch on it, so the common black wire goes to neutral and the brown wire to active leaving the blue to go to one side of the run cap with the other side of the cap going to active/brown. Run it for a very short time and watch for smoke with one hand on the power switch. A single phase motor should draw close to full rated current with no load if you have a clamp meter to check the black wire.
06-27-2009, 07:53 AM #8
It seems a bit strange to me that the resistance between all the leads is pretty much the same. Anyway I suggest that you contact these folks: http://www.groschopp.de/index.php?jump=en and ask, just to be sure. It will be a waste do damage it while you cannot trust the color of the wires.