DC Motor Connection, F2, F3 & A1 together??

[mongo1]

I recently replaced an old 200HP Louis Allis/Magnatek DC Drive with a new 200HP Baldor BC19H series Drive. After installation and a successfull startup I noticed the F2, F3 & A1 Leads were all terminated together at the motor with the A1 armature lead from the drive (F1 & F4 tied to Drives F+ & F-). assuming this was incorrect I had the F2 & F3 leads isolated from the A1 lead, in doing so the baldor reported a phase loss fault and would not run the motor. I had the F2 & F3 reterminated with the A1 lead and the motors been running fine since and apparently ran like this for years. has anybody ever seen this befor or know what i'm dealing with?

 

[Skogsgurra]

What motor is it? Do you have any diagram for it?. Is it an old (20+ years) one? Difficult to say if you do not know the motor. But I have had similar questions about other motors with more than two "F" terminals.

Is F2/F3 a series winding? That should not be needed if you have a "solid state" drive. If the motor is very old, a series winding can be explained, they were used with motor-generator sets. In that case, there should be just one Fx terminal connected to either A1 or A2.

Also, did the drive really report "phase loss"?

More questions than answers, I am afraid.

Gunnar Englund

http://www.gke.org

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

 

[edison123]

Are F2 & F3 leads as thick as A1 & A2 ? If yes, then they are from the series field winding and the motor is a compound field motor (shunt+series fields).

F1 & F4 leads must be of smaller size coming from shunt field winding.

* Women are like the police. They can have all the evidence in the world and yet they still want a confession - Chris Rock *

 

[mongo1]

I dont know what manufacturer motor it is. the motor was lately serviced by a motor rewind shop. I know it does have a series winding that is the same physical size of the armature leads(3/0 or so) that we are not using. It has four field leads labels F1 through F4(14 or 16 ga wire), 2 motor overtemp thermostat wires (14 or 16 ga) that I am monitoring and two additional 14 or 16 ga wires that arnt marked or used that I have no idea about.

 

[DickDV]

I would expect that F1 and F2 are one shunt field and F3 and F4 are a second shunt field. The motor nameplate will likely indicate a dual field voltage as in 150/300V. The shunt field is broken in half so, at 150V the two windings go in parallel and at 300V, the two windings go in series.

I don't know of any configuration where A1 would be in contact with the Field circuit unless the motor was designed for very old battery power.

A better description of the motor with nameplate data would be very helpful.

 

[edison123]

mongo1

It has four field leads labels F1 through F4(14 or 16 ga wire).

I think F1 & F2 is the first shunt field and F3 & F4 is the second shunt field. F2 & F3 were series connected (though I don't have any idea why there connected to A1 at all) and when you opened them (i.e. detached them from A1), the field got opened and hence the "phase loss" fault from the drive.

You can connect F2 & F3 together outside of A1 and I am sure the motor will work fine.

Are there two speeds or two field voltages indicated on the motor nameplate ?



* Women are like the police. They can have all the evidence in the world and yet they still want a confession - Chris Rock *

 

[electrolitic]

Mongo
Probably it is a compound motor ( shunt field winding + series field winding). If you need a fast speed loop control
the series field sense of current changing tends to turn the control unstable. The solution, when applied, is to connect the series field through a rectifier bridge that works as a "directional valve" that guarantees always the same series field polarity.
Regards

 

[mongo1]

Edison123 we left F2 & F3 attached and only detached them from A1 and recieved the Phase Loss Fault. I called Baldor they said an Phase Loss is derived from loosing an incomming AC line Phase. I checked the ac line and semi fuses and everything is as it should be... and the motors name plate isnt any help, it only lists horse power and armature voltage. this one is a real hair puller!

Thank you everybody for your responses.

 

[edison123]

mongo1

the motor was lately serviced by a motor rewind shop

I think the rewind shop is the best place to get an answer.

Thanks for trying my tip. Sorry, it didn't work.

* Women are like the police. They can have all the evidence in the world and yet they still want a confession - Chris Rock *