Identifying electric motor lead wires

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Ken1
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Identifying electric motor lead wires

Post by Ken1 » Thu Sep 20, 2007 6:29 pm

Is there a simple method of identifying the lead wires on a 3/4HP 120/240V single phase capacitor start reversible electric motor? The motor is an old Westinghouse 1725 RPM motor. It has 6 wires in the junction box. The capacitor is good. The motor hums but won't turn. I thing it just might be wired for 240V right now, but I would like to know for sure somehow.
Also, is there a book on AC motors that would explain all the different types and how they are wired including schematic diagrams of each type?

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dacflyer
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Post by dacflyer » Thu Sep 20, 2007 7:54 pm

can you supply the info thats on the data plate ? model # etc..

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Crowbar
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Post by Crowbar » Thu Sep 20, 2007 8:18 pm

One of the best books on the subject...


http://books.google.com/books?id=PpW71B ... le#PPP1,M1
Keep Prying...

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Ken1
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Post by Ken1 » Fri Sep 21, 2007 7:35 am

Westinghouse type FJ induction motor. Serial U20039 Frame 186 single phase 24hr duty. Several patent dates; most recent is 1943. Canadian Westinghouse Company Hamilton Canada.

sparkle
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Older motor connections...

Post by sparkle » Fri Sep 21, 2007 2:49 pm

For a distinguished motor such as yours, my father liked Fractional Horsepower Electric Motors by Cyril G. Veinott, McGraw-Hill, 1939. Veinott was a motor design engineer at Westinghouse. The color codes then were a bit different than the NEMA ones shown at http://www.patchn.com/motor_connections.htm, for dual voltage/main winding only reversible motors, but the basic idea was the same. The main windings 1:GN 2:YEL 3:RED 4:GRAY were hooked in parallel (1 to 3 and 2 to 4) or in series (2 hooked to 3) across L1 and L2, and the auxillary winding, capacitor, centrifugal switch circuit was hooked across the full line voltage for LV (8:RED to L1, 5:BLK to L2), and from the center tap (2,3) to L2 for HV operation. A common and repairable cause for humming no-start motors is a faulty centrifugal starting switch (open). Cleaning/adjusting the contacts is an excellent second troubleshooting step, after first verifying that the shaft is not seized. If your motor has an exposed terminal board, you can temporarily connect all terminals together, disconnect the capacitor, and ohmeter the two capacitor wires. If there is no continuity, something is open in the auxillary starting circuit, likely the switch but could be wiring or winding.

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Edd
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Post by Edd » Mon Sep 24, 2007 1:24 am

.

I am in concurrence on info given to date. Particularly, as is relevant to any internal centrifugal starter contacts.
In my situation I am using a like HP rated motor but running at twice your op speed on a table saw with a 66 tooth carbide blade to get razor smooth cuts.
You didn't specify the application of your motors use....or if merely being bare bones and your subjecting it to a trial bench operational test.
If the motor has been used in woodworking shop environs, that switch is certainly subject to deposition of sawdust down within its innards. Once a film is built up on the contacts, you eventually might only hear a buzzing motor that one time when you hit the power switch.

In my case I am usually cutting hard woods on that table saw, but there is also some pine 2x4's & 2x6's with their high / sticky rosin content.
Their sawdusts tenacious build up eventually insulates that switch contact and I am out of business until a disassembly and clean up of that pair of contacts.The degree of contamination is so bonded, that even a pressurized blast from an air hose will not free it. I say out of business, but really not, since I am so intent on finishing the task at hand that I will lift the pivoted / gravity hung motor mount and flip off (<b>BING</b>....the bird....LOL) the V-belt to the saw blade .
Then I take a 2 ft length of venetian blind cord and multiiiiiii- turn wrap it down within the motors pulley, then give the end of the rope a solid / even tug and then run like hell......no, maybe I THEN flipped the switch,and the motor ran like hell. I then flipped the V-belt onto the running motors pulley and was then able to finish the immediate cutting job at hand.The motor teardown to be done a bit later.
Now with that info on hand, what you might now try is to mechanically secure that motor from movement and starup counter inertia and try that identical manual rope starting technique on it, and even though it might presently be wired for 220 operation it wil cerainly, run for your initial evaluation now on 120 V power-up.
That would then only leave the parting of the motors end cover plates to access the contacts. And I certainly am not expecting any start windings faults..probably just a non-active contact action.

Thassit.
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73's de Edd
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Ken1
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Post by Ken1 » Tue Sep 25, 2007 6:50 am

Thanks for your replies. I got the motor running. 2 things were wrong with it. Both leads of the auxiliary winding were tied together and connected to one side of the line and the centrifugal switch assembly was seized with fine dust. It now works perfectly. As a note 5 of the 6 wires have the same color of cloth braid on them, that's why I needed the advice on wire identification.

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