3 Phase Motor Wiring Trouble

[PhoenixMetal]

I am having trouble wiring a 3 phase motor properly.

The motor is the type with different jumpers to connect to adapt it to different voltages. I have 208V 3-phase power.

Here is the wiring diagram that came with machine:


When I hooked it up for the 220V option, the motor seemed to be running way way faster than it should have and the high pitched whining noise coming from it just seemed unhealthy.

So, I hooked it up for the 440V option, and it seemed to work normally. However, when a serious load is put on the machine (well within the limits of what the machine is supposed to be capable of), the motor bogs down and doesn't have enough power.


I noticed the diagram shows a Delta (triangle) sign above the 440V option, and TWO Deltas above the 220V option. Does anybody know what these symbols mean and does it explain why the motor didn't run normally when jumpered for 220V?

Is there some special way I need to wire the motor up to get it to work properly?

Any help would be greatly appreciated. Thanks!

[Al_The_Man]

Is this a 2 pole or 4 pole motor? it should say the rpm on the motor plate.
It should not be able to run any faster than it is capable of on 60hz, this is what decided the rpm, not the connection.
Hook it up to 220 the way the digram shows and check the off load current.
The symbols are star (wye) and delta for the triangle.
The 220 appears to be both delta windings in parallel.
Al.

[PhoenixMetal]

Originally Posted by Al_The_Man Is this a 2 pole or 4 pole motor? it should say the rpm on the motor plate. It should not be able to run any faster than it is capable of on 60hz, this is what decided the rpm, not the connection. Hook it up to 220 the way the digram shows and check the off load current. The symbols are star (wye) and delta for the triangle. The 220 appears to be both delta windings in parallel. Al.

Hi Al,

I'll check in the morning as to the 2 or 4 poles, run the current test that you reccommended and will get back to you.

By the way, when I said it was running way faster than normal, that statement was really based mostly on the sound it was making - so it is possible that it was still running its normal speed. The motor is running a hydraulic pump, so its not as if I was able to clearly view things moving faster or slower. However I really do think it was running way fast. But faster or not, the motor definitiely was not making happy noises when I had it jumpered for 220!

What does it mean to have the delta windings in parallel? Is this perhaps specifying a certain type of power supply that is different from what I have?

[Al_The_Man]

If the motor was connected to the hydraulic pump, it is most likely the whine you heard is from the pump.
The Delta in parallel connection is what appears to be the designated connection for 220.
Your voltage is the lowest of any of the designated connections, so anything but the correct connection is going to be underpowered.
Al.

[PhoenixMetal]

Ok, I have checked the faceplate on the motor to determine whether it is a 2 or 4 pole motor, and unfortunately it doesn't say. However perhaps its model number (FC112MT/4) gives a clue (the 4) suggesting that it is a 4 pole motor.

[rlabonte18]

2 pole will have an rpm around 3000 and a 4 pole will have an rpm around 1700. Yours is probably a 2 pole motor.

[Al_The_Man]

Doesn't it mention rpm on the plate?
If the pump is connected and the current is within the FLA which hopefully it also mentions, then it should be OK.
Al.

[PhoenixMetal]

Originally Posted by Al_The_Man Doesn't it mention rpm on the plate? If the pump is connected and the current is within the FLA which hopefully it also mentions, then it should be OK. Al.

The plate says 1704 RPM. I have found some literature online from the motor manufacturer and it looks like this is in fact a 4 pole motor.

OK, but now what does this tell you?

[Al_The_Man]

Originally Posted by PhoenixMetal The plate says 1704 RPM. I have found some literature online from the motor manufacturer and it looks like this is in fact a 4 pole motor. OK, but now what does this tell you?

The 1704rpm confirms it is a 4 pole motor.
I was just trying to get an idea of what rpm you should be getting.
You need to confirm the running current, that will tell you if you have the hook up wrong.
Hopefully the motor plate shows FLA's or the H.P. at least.
Al.

[PhoenixMetal]

Hi Al,

The motor lists 4.8kw as its power.

I was going to do the current test that you requested, but then realized I have no idea how to do this on a 3 phase motor!

I can imagine how to do this on a normal AC or DC motor, with only 2 wires, but how do I do I measure current on a motor that has 3 leads?

[Al_The_Man]

That is around a 6HP motor so you most likely would draw ~18amps max. at full load on 220v.
The easiest way to measure the current is to borrow a clamp-on ammeter, this clamps over each conductor in turn, no contact is necessary with any conductor directly.
If you are running under 18amp on each conductor, you should be OK.
Al.

[jpgdesigns]

Just a thought... you said this motor is running a hydraulic pump... some hydraulic pumps do not like to be run in reverse... so be sure of your rotation.