Winding Resistance Fractional HP Motor

[PNA]

We had an issue back tracing some wires through a terminal strip. There are 4 - single phase 110Vac 2 pole motors, each hot wire connected to an individual terminal.
Neutral/Common are all connected on a busbar.

What occurred when i did some continuity tests with a multimeter, was if i put 1 lead on the hot wire of 1 motor, i would get continuity through the other 3 hot wires BUT not through the neutrals.

Kind of thrown off by this.
I thought that with a continuity test, if the resistance is too high (which through windings of a motor lead me to believe that) i shouldnt be able to have continuity through all 4 motors.

Any ideas?

Paul

 

[Skogsgurra]

I can't quite follow you. Is it the fact that you have continuity through the motors that disturb you? Most windings are quite low ohm. So you should have continuity.

Or is it the fact that you don't have continuity from winding to neutral that you find confusing? That is also perfectly normal - there is no connection to neutral in a three-phase motor.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[aolalde]

PNA

Please clarify.
4 single phase motors. Two terminal leads per motor?
Connected to different phases of a 3-phase system?
I assume the motors are off line when the continuity test is performed, is it? but one terminal (to neutral) is still tied to the other 3 common leads?

 

[PNA]

Thanks for the responses

This is a 110 Vac single phase 60 hertz Canadian.
1 hot wire (black) 1 neutral wire (white) and 1 ground wire (green).

(For the UK and Europe, it would be 220/230/240 single phase) which is 1 hot wire (brown), 1 common (baby blue), 1 ground or pe (green with yellow)

We have the motors each on there own switch.
All switches are off.

There is no power applied to any motors.

Yes 1 terminal is tied to the other 3 common leads.

Paul

 

[bklauba]

I believe that the signal path the ohm meter is "looking" is: Thru the motor whose hot lead you have one meter lead on, which has continuity to the neutrals (whether tied together there, or earlier in the control or ultimately, the electrical service panel) have continuity to all three motors thru their windings. If the motors each have a DC resistance, for instance, 100 ohms, then you should be seeing 200 ohm readings from any motor hot to any motor hot.

BK

 

[waross]

Try to measure continuity from one spot on the neutral busbar to another spot on aathe neutral busbar. If you still don't get continuity, clean the surface of the busbar and try again.
respectfully

 

[jraef]

Yes, I too think the problem here is in your not measuring continuity to the neutral(s). You should, AND that would coincide with your being able to measure through to the other hots. Probably a measurement error, i.e. bad connection as waross implied.

JRaef.com
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