Unclarity about wound rotor of old motor and VFD

[pafkatata]

Hello,
I have problem with an old asynchronous motor with wound rotor it is VEB MEZ VSTEIN.I am intending to run the motor via frequency inverter by connecting it to the stator windings. I need to short circuit the rotor, but there are 6 poles coming out (a,b,c and a0,b0,c0) from the wound rotor collector and I don’t know which one to connect to which.it is quite huge motor it is in a testing facility. It is rotating a big fan in a tunnel and its purpose is to simulate a wind with a particular speed.But the guys want to get rid of this old scheme connection and want to control it via frequency converter. Actually i did this but with a normal asynchronous motor with wound rotor with only 3 poles on the rotor which i had to get short circuit them to each other, but this monster has 6 poles as you can see on the scheme (maybe 3 for the beginning and 3 for the end of the rotor winds). Can you help me with advice what to do with these 6 poles coming out (a,b,c and a0,b0,c0) from the wound rotor collector?

 

[rasevskii]

pafkatata:

From the dwg it is not clear what the rotor connections are. Does the motor have actually six sliprings, or is it a commutator? If it is a commutator, does it have a brush-shifting mechanism? If so it could be a Schrage motor. If not a shiftable brush rigging it looks like a Scherbius system. Were once rather widely used systems in the Germanic world. You are in former E.Germany, from the VEB it would seem so??

What is the KW rating and the speed range of the motor? Voltage?

Just some guesses...

rasevskii

 

[LionelHutz]

It appears the connections are each end of a winding. An ohmmeter check should be able to tell you if that is possible or not.

Is that a slip energy recovery system using a big motorized variac?

 

[pafkatata]

I am posting another photo now because i can post only one photo per post.This one is the rotor inside and connecting to these brushes, as you can see there 6 lines overall but here you can see only 4.

 

[pafkatata]

Posting another photo from the motor plate.

"Is that a slip energy recovery system using a big motorized variac?". I doubt it but I am not sure.

 

[rasevskii]

pafkatata:

This is not by any means a wound rotor induction machine, rather it is a variation of a Schrage machine using fixed position brushes, speed control is via the motorized induction regulator shown on your dwg. I will lookup the name of this type of machine. meanwhile do a Google of "Schrage Motor" and you will find a lot of info including a couple of huge PDFs on how this works.

I don`t see why you want to replace this with a VFD, which would seem to require replacing this motor with a VFD-compliant induction motor. It is only about a 20KW unit. But that is a question of costs versus keeping the old system.

rasevskii

 

[rasevskii]

pafkatata:

This could be a "Higgs Motor", the connections of which you will find on the "48_Folta" PDF which you will find when you Google "Schrage Motor". See page 37 of that PDF. Now, who was "Higgs"
anyway...?

A bit of Electrical Archaelogy required here...

rasevskii

 

[pafkatata]

rasevskii:
Thank you very much for the info so far. Please check in the next few days.I will post more photos and info about this motor.

 

[automatic2]

Not sure what you'd term the motor, but I'm guessing that the commutated field is being driven by a Leblanc exciter, where the field is sourced from a parallel line feed, but the lag is pushed out by the smaller converter. Starting your machine is a question. VF drive is an option, opposed to induction or other drive. I'd VFD the mainline which included the sync and exciter. You shouldn't then require external start drives. Brush shorting is typical in induction start.

 

[7anoter4]

I am not sure it is actually a Shrage Motor but you can contact the TES VSETIN and get some more information. This series SH is now for DC motors but you have a DYSH motor of 155 A, 180 V, 50 Hz speed variable from 350 to 2800 rpm. So I think is would be better if you could contact the Manufacturer.
See:

http://www.tes.cz/en/services/repairs/

 

[automatic2]

Could also be a synchronous generator being run as a motor.