Siemens Rotary Switch

[Scra99tch]

I have an old German cylindrical grinder I have been working on and I am trying to understand the 6 lead motor wiring on a 2 speed motor.

The switch disintegrated and left me with a motor that buzzes when the switch is turned on it eventually trips the breaker.

The motor wiring starting with the 6 leads goes UaVaWa above, below that is UbVbWb. The plastic identification clips used on the wires are on top U8V8W8 and below that are U4V4W4.

So measuring the resistance on the U winding its about 70 ohm, on the V winding about 70 ohms and on the W winding about 140 Ohm's

The voltages follow the same pattern about 220V on U and V and about 440 on W. When I flip the rotary switch I get the buzzing but was able to see on my multimeter about 2 A's being drawn on the U winding, before it tripped.

Below are some pictures of the switch. My question is how many poles is this switch 3? What would I be looking at for a replacement considering the motor wiring? There seem to be plenty of modular rotary switch on line that can handle the voltage reuqirements but not sure on what I would need considering the configuration of the siemens over engineered broken one.








I

 

[markba633csi]

OK so that's a 3 phase motor, so the switch must be basically 3 pole. But it may have a special switching arrangement to switch between the 2 speeds.
I believe the motor windings are similar to other two speed, 3 phase motors, there should be some info on this site about it somewhere
It runs on 380 volts at low current so easy to power it from a VFD
For the sake of originality you could try gluing the switch back together with JB weld since it looks like you have all the pieces.
-Mark

 

[Scra99tch]

OK so that's a 3 phase motor, so the switch must be basically 3 pole. But it may have a special switching arrangement to switch between the 2 speeds.
I believe the motor windings are similar to other two speed, 3 phase motors, there should be some info on this site about it somewhere
It runs on 380 volts at low current so easy to power it from a VFD
For the sake of originality you could try gluing the switch back together with JB weld since it looks like you have all the pieces.
-Mark

Its blown apart pretty good, theres more not included in the pictures, plus I am not sure If all the cams on the central post are in the position they where when I pulled it apart.

 

[markba633csi]

How are you planning on powering it? You notice that it's 380 volts/ 50 Hz

 

[Scra99tch]

Yeah I have a transformer 220 - 400V running it. I had it moving until something went wonky. I believe the cuplrit is the switch somehow but not sure how or what went wrong with it. I mean what in the switch was causing the breakdown and subsequent short.

I dont believe I have any burnt windings in the motors as I am getting consistnent ohmic readings off the three.

 

[markba633csi]

I seem to remember Jim Dawson posted a very helpful diagram once that showed how those motors are connected and the switching arrangements
If I can find it again I'll post it here
It showed the differences between the Y and the Delta connection and how you switch between them

 

[Scra99tch]

Here is the schematic of the switch as best I can depict it. Like I mentioned I have not idea how the cam's were in the switch and what contacts were left open and closed when shaft was rotated. Hoping someone has enough knowledge to figure it out can I am at a loss until I get to look and understand what is really going on.

 

[Scra99tch]

.

 

[graham-xrf]

It may help if you check out --This Thread from post #44 onwards.
It covered that type of rotary switch, and discussed the wiring up of them, ranging through various kinds of motors, reversing switch wiring, and changing for 220/240 VAC conversions.

It also ends up with all the correct switch connections diagrams, if you chase the thread far enough.
The discussion on the way amounts to a motor wiring education.
I believe you can get replacement switches in that same style that do the trick, though possibly not the same brand as the broken one.

 

[Scra99tch]

Awesome thank you.