wiring a three phase motor

I'm hooking up the hydraulic oil pump on my CNC lathe. Its a standard 9 wire motor so it can be wired 220 or 440 three phase. My trouble is that the IDs on the wire leads are almost unreadable and I'm not sure I have it connected correctly. Especially sense I have U1, U2, U3 and V1, V2 , V3 - can't tell a U from a V.

Will I smoke the motor if I have a lead switched? Or will the motor just hum with no damage? Are there any tests I can do with a multimeter to check before giving it the juice?

Also, after it runs, how do I check for correct rotation direction. Just leave a hose open and wait for the oil to squirt?


Reply to
Karl Townsend
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If I were you I'd make 9 legible labels, printing them on label tape. Then I'd go after that sucker with a connectivity tester, knowing the standard 9-points-on-a-spiral diagram. Clean the existing labels as best you can and use strong light and magnifying lenses. Figure out what the labels are using your brain and the measured connectivity data and the labels you can discern, and then relabel them properly. If the wires are in bad shape, consider sleeving them with heat shrink and/or extending them.

With all wires disconnected:

1 should be connected to 4 2 should be connected to 5 3 should be connected to 6 7 should be connected to 8 which should be connected to 9

440: connect 47, 58, 69 power to 1,2,3

220: connect 17, 28, 39, 456, power to 1/7,2/8,3/9

Here's some ASCII art:

1 / \ / \ 4 7 / \ / \ -*- | | - - | | 9 8 6 5 - - | | - - | | 3 2

Once you have it running, run it briefly to see if you have fluid, and if not, reverse any 2 power connections and try again.

Easier to do than to describe, but still a bit tedious.

Grant Erw> I'm hooking up the hydraulic oil pump on my CNC lathe. Its a standard 9 wire

Reply to
Grant Erwin

I don't know what you mean here. What's a nine point on a spiral diagram? FWIW, the wires are labeled u1 u2 u3 v1 v2 v3 w1 w2 w3, not 1 - 9. The little label on the motor cover talks about connections R, S, and T and I can't find this anywhere. These wires have been soaking in hydraulic fluid for twenty years - kinda hard on ink.

How do I measure connectivity? Am I looking for a certain ohm reading between wires? There's 9! (factorial) combinations of wires to test ohms between. I've done my VERY best at sluething with strong lights etc. but there's a very real chance I have it wrong as at least four of the wires are totally unreadable.

Sorry to be such a dumby, I need a little more help here. Or won't it hurt to just plug it in for 2 seconds to see if it spins? I think its right, but I don't KNOW its right.


Reply to
Karl Townsend

"Karl Townsend" wrote in news:phfmb.419$ snipped-for-privacy@newsread4.news.pas.earthlink.net:

Perhaps this will help. There are 6 windings in your motor. Since each winding has a wire coming out at each end there are 12 wires to connect. You only have 9 wires coming out of the motor, so clearly some wires are already connected.

Three of the windings have both wires coming out, that's 6. Three of the windings only have one wire coming out for a total of 9. The three wires left are all wired together inside the motor.

All of the windings have the same resistance. If you take an ohm meter and start measuring pairs of wires, you will get 3 different answers depending on which pair you happen to choose. You will get a resistance we will call R, you will get a resistance of twice R, and you will get a resistance which pegs the meter which means no connection. You should get 3 pairs with resistance R. Those are the windings with both wires coming out and should account for 6 wires. You should get 3 pairs with resistance 2R which should be the three distinct pairs you can make from the remaining 3 wires.

In the US at least, the standard way to label the wires is T1 to T9 in the following way. One pair with resistance R between them will have wires T1 and T4. One will have T2 and T5. One will have T3 and T6. The three wires which have the 2R resistance pair by pair are labeled T7, T8, and T9.

For the lower of the name plate voltages, connect T4,T5,andT6. Connect T3,T9,L1 (where L means line). Connect T2,T8,L2. Connect T1,T7,L3. Swapping any two lines will reverse the direction.

For the high voltage, connect T6 and T9. Connect T5 and T8. Connect T4 and T7. Connect each of the remaining wires (T1,T2,T3) to one of the line wires. Again, swapping any pair of line wires will reverse direction.

Reply to
Charly Coughran

Many thanks. I'll start measuring stuff.


Reply to
Karl Townsend

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