Unclarity about wound rotor of old motor and VFD
Unclarity about wound rotor of old motor and VFD
(OP)
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?
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?





RE: Unclarity about wound rotor of old motor and VFD
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
RE: Unclarity about wound rotor of old motor and VFD
Is that a slip energy recovery system using a big motorized variac?
RE: Unclarity about wound rotor of old motor and VFD
RE: Unclarity about wound rotor of old motor and VFD
"Is that a slip energy recovery system using a big motorized variac?". I doubt it but I am not sure.
RE: Unclarity about wound rotor of old motor and VFD
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
RE: Unclarity about wound rotor of old motor and VFD
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
RE: Unclarity about wound rotor of old motor and VFD
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.
RE: Unclarity about wound rotor of old motor and VFD
RE: Unclarity about wound rotor of old motor and VFD
See:
http://www.tes.cz/en/services/repairs/
RE: Unclarity about wound rotor of old motor and VFD