[Tomaz-dentas]

Hi,

our Cincinnati Arrow 750 is displaying that its spindle is under 40% overload even if its just spinning freely. Even when its going into tool change its displaying overload.
When turned off the spindle rotates normally. So we think that the bearing are fine.
Has anyone ever encounter with problem like this?

Thank you

[gwood]

TD, I would shut down the machine and lock-out the electrical power. Then mark & disconnect the a,b,c (u,w,v) armature wires at the spindle drive.
1) Use a high quality DMM to Ohm the 3-leads going out of the M-11 Contactor to the spindle. Leg-to-Leg A-b, A-c, B-c. They should all be low-Ohms the same within .1 Ohms.
a) If different check for loose or broken wires, or go to step 3)
2) Have someone gently push in the m-11 contactor with a plastic pen and hold it in. Take the same measurement from the wires disconnected at the drive. Results should be the same.
b) If different check the M-11 contacts for arcing.
3) If you have a Meg-Ohm Meter (Insulation Tester) the armature wires can be meggered at 1000V by a trained electrician, from the M-11 contactor as well.
4) When finished reconnect the 3-wires disconnected.

[Tomaz-dentas]

thanks for the reply, but we checked the contactor and its working alright. Is there anything else we can check?

[maver1ck]

thanks for the reply, but we checked the contactor and its working alright. Is there anything else we can check?

What Greg suggested was a lot more than just checking the contactor. Perhaps you should reread his suggestions and look into the rest of it.

The load meter is displaying what the spindle drive sees

[maver1ck]

The load meter displays what the spindle drive sees as happening. You could have an issue in the spindle drive reporting an incorrect load, but more likely is that the spindle drive is working hard to keep the motor at the speed set point because something is making it do that.

As Greg suggested, motor and cable issues could cause this, but you could also be getting erratic feedback signals causing it to constantly adjust output to compensate.

[Tomaz-dentas]

My coworker checked the contactor or at least he said he did, he measured all the wires with load meter and everything was in order. But today we found out that the contactor is burned. So now that we know the problem we need to find a new contactor, we are in EU and the company that made the contactor is not making them anymore, even the company that sells spare parts isnt making them anymore. Does anybody knows where we could find new contactor.

[meckardt55]

I would remove the contactor and take it to an industrial electrical supply company to size it up for the voltage and current. You can use any similar contactor with the same rating and coil voltage.

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