3 Phase Delta WYE Resistances

[Scra99tch]

So the motor connection I have is 6 lead.

U1 V1 W1

U2 V2 W2

If I measure across from U1 to W2 I get 71.9 Ohms
from V1 to U2 I get 128 Ohms
from W1 to V2 I get 71.9 Ohms

If I measure from U1 to U2 I get 71.8, from V1 to V2 I get 71.9 from W1 to W2 I get 128.2

This I take it means it is wired for both. If I want high speed I bridge U1,V1,W1 with line in for WYE or star winding.

My question is why the higher resistance on one of the windings should they not all be the same.

Thanks

 

[markba633csi]

They should be the same, there may be a problem. Hard to say what it is, if there was a short in one winding you would expect one winding low and the other two high.
Have you measured them to ground? (the case)
-Mark

 

[Scra99tch]

Yup all are open to ground. NO resistance on any leads to the case. Which is I good sign.

I am just wondering being a two speed motor could they have wound the wires a few more loops on one of the windings or used a different smaller gauge?

Have not read anywhere to be the case, that different gauge wires are used in windings.

 

[markba633csi]

Here's a diagram of a typical 3-phase unit- no matter how you measure it it should be equal on all three sides
So looking at the series delta- low speed diagram I'm thinking that one of the six junction points is open: T1 thru T6 Just a guess
Try measuring U1 to U2, then V1 to V2, then W1 to W2 see what you get

 

[Scra99tch]

U1 to U2..... 70.1, 70.2 and 128

 

[markba633csi]

Seems to be something fishy with the W1 to W2. See if wiggling the wires changes the reading. I guess the next step would be to open up the motor.
There may be a flaky solder joint

 

[Scra99tch]

Okay.

This is the motor in question don't know how much its changed from the one I have from 1968.

I'll try disconnecting all the wires and pull it apart.

Three-Phase Asynchronous Motors KOD - GEORGII KOBOLD

www.georgiikobold.de

 

[Scra99tch]

So it is a two winding motor. Measuring across UaVa, VaWa and UaWa I get equal(ish) ohm readings, tying UaVaWa together and measuring UbVb, VbWb, and UbWb I get another set of equal(ish) readings.

Motor is good, I confirmed by supplying line voltage to each setup and strobe'd the pulley speed which is close to printed speed. I checked the current draw with my amp meter and both speeds pull stated amperage.


Now for the hard part, anyone want to take a stab at my Dahlander switching problem??

 

[Lo-Fi]

Now for the hard part, anyone want to take a stab at my Dahlander switching problem??

I think I've missed that somewhere?

 

[Scra99tch]

I've posted to numerous places so maybe not in here yet.

The old switch was a Siemens switch made out of bakelight and it crapped the bed causing one of the cams not not function. I was not able to get the cam position initially when I pulled it apart.

I bought a new dahlander switch and when hooked up to the above configuration on position 1 of the switch which would be 123 (UaVaWa of motor leads) contacted to RST. The will motor hum and will trip the breaker in both low and high speed position. I can send a picture of the new switch also if need be. But the picture below is the wiring diagram for the new switch as you can see there is 4-5 places where terminals are shorted. On the old switch there are 3 terminals which are shorted.