I have a pump motor that I was trying to wire. It's been a long time since I've wired a motor and I haven't seen one with just 4 wire connections- U, V, W, and ground. I have 220v 3 ph power.

Can I wire it directly to a plug that can be plugged in to turn on and run the motor? Or do I have to have a controller?

Also do my red and black wires go to the U and V terminal and the neutral wire to the W terminal? That other terminal is the ground.

Thanks for y'alls help!enter image description hereenter image description here

  • \$\begingroup\$ What country you live? Are you sure you have 3x220V/60Hz or you are wrong and you have 3x400V/50Hz. You should have 5 wires: 3 phases, neutral, ground. Forget the neutral for this case. Measure the phase to phase voltage. \$\endgroup\$ – Marko Buršič Sep 1 '17 at 6:49

U, V, and W are all power. Ground is obviously, ground. Uggh, I can't read Chinese. :)

In three-phase 220v AC, the UVW colors are all but meaningless. They may be black/red/white, or yellow/orange/red... really anything. But a "neutral" should never be used in 3-phase wiring.

You can wire them in any order. If the pump runs in reverse (hope that doesn't destroy it...) just switch any of the two leads - like U and V. Then it will run in the other direction.

Any 3-phase motor should be fused, and the vast majority use a contactor (glorified relay) to start/stop. The proper way to wire this would be SOURCE --> FUSES --> CONTACTOR --> PUMP. Then it's "always on", and simply activating the contactor (which can be done from 220 or even 110) starts and stops the pump.

  • \$\begingroup\$ "But a "neutral" should never be used in 3-phase wiring." You should qualify this. Obviously it is used in for certain applications but generally not in three-phase motors. \$\endgroup\$ – Transistor Sep 1 '17 at 8:00

The wiring here is 3-phase "delta", meaning 220V between any two phase wires. Note the symbol above the 60Hz mark. You can supply it with either 220V "delta" or 220V "wye", in both cases phase-to-phase power must be 220V.

In the case of "wye" or "wild-leg delta" you will not be using the neutral. Keep in mind that in most of the world, the power is "wye", 220V phase-to-neutral/ground and 384-400V phase-phase. That is the wrong power for this.

"W" has nothing to do with "white". That is unrelated.

Assuming you are in the North American sphere of influence for wiring (Japan, parts of Philippines, American possessions), white means neutral. You would not be using neutral.

Now, if you are using multi-wire flexible cable, the stock colors are black white red and ground. This type of cable will work fine for 220V "delta" wiring, but make sure it is actually connected to real 3-phase with a triple breaker or triple fuses. If it is fed by a double breaker, that is 120/240V split-phase, white is neutral, and it cannot power this motor.

In this case you would be using white for a hot phase, so you need to wrap several loops of black or color tape around the wire to mark it as not a neutral. Do this on both ends of the wire if possible. Black tape is fine, it doesn't matter what colors the 3 wires are, as long as they are not white, gray or green.

You hook the three hot wires to the three U,V,W terminals. It doesn't matter which is which however you have a 50/50 chance of the motor spinning the wrong direction. You need to be on guard the first time you start it up to check for correct rotation, and shut it off immediately if wrong. The motor will be happy spinning either direction, but the pump may not. (This can really getcha with air compressors, they seem to work but the oil pump is running backwards. Rebuild time!)

If it does spin the wrong way, swap any two of the hot wires.


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