# Kostov Motor



## Guest (Apr 6, 2009)

I am finishing up my Kostov but I am having some trouble. The motor is a series motor with interpoles but it has 6 terminal posts. 2 for the main field windings and 2 for the interpoles and 2 for the brush ring. Most series motors have 2 for the main fields and 2 for the brush ring for the armature. My interpoles are separate from the main fields and that gives 6 terminals. I am needing to know how this is actually wired. On other Kostov motors I do not see 6 posts but only 4. I am unable to see how the brush rings are wired to the motor. Can anyone help? It is for sure a series motor and not a shunt or compound. It is just a series with interpoles. Here is my photo album with photos to look at. I have sent a request to the company that makes Kostov motors but have not yet gotten a response. I do not expect to have a fast response but I think they will this week. If any of you have any insight or help I would greatly appreciate the help.

Thanks
Pete : )

http://greenev.zapto.org/kostov


----------



## major (Apr 4, 2008)

gottdi said:


> My interpoles are separate from the main fields and that gives 6 terminals. I am needing to know how this is actually wired. Can anyone help? Thanks
> Pete : )


Hi Pete,

The interpole coils (called comm coils) are usually hard wired in the armature circuit, in series with the armature, in the A1 to A2 circuit, in normal convention. Then only the main field is in the S1, S2 circuit. This is the first time I've seen separate terminals for the comm coils. I guess it was done because wiring the comm coils, which are physically located in the field structure, into the armature circuit, which is in the end bell with the brushes, is a bit tricky. So just leave it to the user.

The polarity of the comm coils (the N,S polarity of the interpoles) always stay the same relative to the armature, regardless of direction of rotation or motor/generator mode. This will be a bitch to figure out. You'll have to wire it up without the comm coils connected, and determine the rotation direction and which main poles are the N and S. Then determine the current flow direction in the armature circuit, like into A1 and out of A2. From there figure out the N/S relationship for the interpoles relative to current flow direction in the comm coil circuit. I can't remember which is required, N or S, for the interpole leading the main N pole. I'll see if I can find a web page showing this.

Or, you can simply take a guess and wire the all the circuits in series, run it at no load, reduced voltage and observe commutation. Then switch the polarity of the comm coils and repeat. Which way sparks less? Bingo

Regards,

major


----------



## Guest (Apr 6, 2009)

Below is a picture of the motor plate showing the field posts. No mention of the armature posts. I am thinking that the armature posts actually wire up to the field posts within the motor but I see no way for two more wires going up the access hole for mounting the posts. It is just an odd thing.


----------



## major (Apr 4, 2008)

gottdi said:


> Below is a picture of the motor plate showing the field posts. No mention of the armature posts. I am thinking that the armature posts actually wire up to the field posts within the motor but I see no way for two more wires going up the access hole for mounting the posts. It is just an odd thing.


Pete,

The nameplate shows the normal way for interpole motors. The 3 hump coil symbol between B1 and the circle, representing the armature, represents the comm coils. This indicates that the comm coils were hard wired in the armature circuit, between B1 and A2.

I suspect someone has modified this motor. Moving the A terminals to those funky white insulator posts hanging out there. And connecting the comm coils to the terminal plate on the frame.

Regards,

major


----------



## Guest (Apr 7, 2009)

major said:


> Pete,
> 
> The nameplate shows the normal way for interpole motors. The 3 hump coil symbol between B1 and the circle, representing the armature, represents the comm coils. This indicates that the comm coils were hard wired in the armature circuit, between B1 and A2.
> 
> ...


I was thinking of that too but the original field coils that you see are no different. I see no where you can attach the armature to those field windings. I will ponder this some more. I was hoping to find something in my box but no go. It is what it is. I just need (want) to know. The guys at Kostov are going to send me some drawings. I was hoping someone here had some good photos of how the armature is attached to the field coils.

Pete : )


----------



## Guest (Apr 8, 2009)

Well we now have the 6 terminal post issue figured out. Those posts on the brush ring do not belong. The motor had been modified long ago but never put back into service since the modification. The interpoles are supposed to be connected to the brush and they are in series with the armature. The connecting points are connected together and should not be. I can reverse the modification with no issues to the performance or operation of the motor. I have found a site that where a Kostov was dismantled for repair and cleaning and I also got some excellent information direct from Kostov. I have a bunch of new photos in my album. I feel that the Kostov is an excellent alternative to the other motors and the Kostov also has interpoles where the others do not. These may not be perfect for a race car but for a good street car with decent performance they should be quite reliable. There are more out there being used than you may think. There are alternatives to the common ADC or Warp motors. 

http://greenev.zapto.org/kostov

Pete : )

I will be rewrapping my field windings and learning a good deal about DC motors. I will be getting some advice from Jim Husted. He has been very helpful during the past year. This will be an excellent project to learn about DC motor repair.


----------



## Telco (Jun 28, 2008)

So... any idea what the intended use of the extra poles was for? There must have been a reason for them to be added.


----------



## major (Apr 4, 2008)

Telco said:


> So... any idea what the intended use of the extra poles was for? There must have been a reason for them to be added.


Telco,



> *Interpoles *
> *Interpoles are similar to the main field poles and located on the yoke between the main field poles. They have windings in series with the armature winding. Interpoles have the function of reducing the armature reaction effect in the commutating zone. They eliminate the need to shift the brush assembly. *


courtesy of Reliance Electric


----------



## Guest (Apr 8, 2009)

Yes that is correct. What someone did was connect the interpole fields together and did not attach them to the brush ring where they belong. After that they realized they needed a way to attach to the interpoles and they installed those funky extra posts. I found the place where they connected the interpoles and it is an easy fix. I am missing nothing except an original cooling fan and cover housing for the fan which I can buy new if I want. The Kostov rep has been great. 

Pete : )


----------



## DIYguy (Sep 18, 2008)

Hey Pete,

Nice find. I like the idea of the Kostov for sure. Where did you pick it up?

Also, I saw a pic of another motor you have somewhere. Series DC.... I have a GE motor out of a forklift and I swear it is exactly the same motor. I would love to get some specs from yours. I think it is a 9" right? and the length is? The close ups I saw were the same as mine. I have a Hyster name plate for mine that leads to dead ends. Jim Husted told me that it is a good motor for an EV.

Cheers.
Gary
Sorry for hijacking...should have sent u a PM


----------



## Guest (Apr 9, 2009)

DIYguy said:


> Hey Pete,
> 
> Nice find. I like the idea of the Kostov for sure. Where did you pick it up?
> 
> ...


I picked up the motor on the bay area over a year ago. My Ghia has a GE 9" DC Series Motor. I also have another one I recently picked up. Both are the GE 9" and yes they are excellent for EV's. There are a few who run these motors and they are able to run 144 volts easy and the GE 9" is capable of a bit more in the RPM department. I was told to keep it within 5500 rpm while my Kostov should be kept within the 5000 to 5200 rpm limit. Go to my EV site and see the photo album. You will see the new one there too and it has a motor plate. The motor plate is for it's original purpose so the voltage is low and the amps are low. These motors do not have internal fans so it is important to keep them cool. For now my motor is staying cool but before the summer is over I will be installing a cooling fan. 

http://greenev.zapto.org/ge

Pete : )


----------

