Generators and Motors
[Home] - [HELP] - [Forums] - [Articles] - [Photo Gallery] - [Groups] - [Chat] - [Classified Ads] - [Subscribe] - [Links] - [Books] - [Sponsors] - [Tools]

Go Back   SmokStak > SmokStak® Vintage Electrical Equipment > Generators & Motors General Discussion > Onan Generators
Forgot Password? Join Us!

Notices

Onan Generators Restoring, operating and maintaining vintage Onan generators.

Onan Generators

How-To, Exciter Rewind (both Stator & Rotor)


this thread has 20 replies and has been viewed 7953 times

Reply
 
Thread Tools Display Modes
  #1  
Old 05-07-2010, 01:12 AM
a31ford a31ford is offline
Registered-II
 
Join Date: Nov 2004
Location: Brandon, Manitoba Canada
Posts: 41
Likes: 12
Liked 20 Times in 8 Posts
Photo How-To, Exciter Rewind (both Stator & Rotor)

Greetings all,

I've decided to do a mini-series on rewinding the exciter (brushless) set on a 32Kw Onan head (MDKAF serial #002) this unit was the benchtest for onan when they first started making this model, so the unit has some notable history behind it.

NOTE: that the exciter set (Stator & Rotor) are NOT electrically burnt, rather they where damaged with a bar or chisel after the set was decomisioned from the testing.

The main armature and stator are in fine shape, it's just the exciter that was damaged.

I've pressed the excitor off the main shaft and removed the feild from the back housing plate, I've ordered wire, sinthite varnish, waxed lacing cord, and insulation paper from my supplier, the freight is MORE than the cost of the supplies (almost 2X) But... there is enough to do 2 or 3 more sets of exciters.

As the supplies arrive I'll document and photo the process.

I expect the entire thing to happen over the next 4-6 weeks, as I'll be doing the rebuild in-between other things, and the final cooking will take 3-4 days alone.

Will continue this thread as things arrive.
Reply With Quote
The Following 8 Users Like This Post:
Sponsored Links
  #2  
Old 05-07-2010, 09:47 AM
TomFG's Avatar
TomFG TomFG is offline
Registered-III
 
Join Date: Nov 2004
Location: Minnesota USA
Posts: 416
Likes: 1
Liked 29 Times in 13 Posts
Default Re: How-To, Exciter Rewind (both Stator & Rotor)

Sounds interesting. Will be looking forward to the presentation!
Reply With Quote
  #3  
Old 05-07-2010, 01:04 PM
BTPost's Avatar
BTPost BTPost is offline
Moderator
 
Join Date: Jan 2005
Location: Excursion Inlet, Alaska USA 99850-0090
Posts: 4,651
Likes: 514
Liked 1,713 Times in 1,131 Posts
Images: 1
Talking Re: How-To, Exciter Rewind (both Stator & Rotor)

When you get it done, We will look at making a FAQ Sticky out of it.....
__________________
Bruce in alaska
Reply With Quote
  #4  
Old 05-10-2010, 11:33 AM
Deneh Deneh is offline
Registered-II
 
Join Date: Oct 2008
Location: Herlong, CA
Posts: 44
Likes: 8
Liked 4 Times in 4 Posts
Default Re: How-To, Exciter Rewind (both Stator & Rotor)

I'm a Ex-Navy rewinder and work for the US Army now, formally repairing generators. I am REALLY looking forward to learning more about these Onan's from your upcoming article!!
AWESOME!!!!
Reply With Quote
  #5  
Old 05-22-2010, 09:55 AM
a31ford a31ford is offline
Registered-II
 
Join Date: Nov 2004
Location: Brandon, Manitoba Canada
Posts: 41
Likes: 12
Liked 20 Times in 8 Posts
Default Re: How-To, Exciter Rewind (both Stator & Rotor)

UPDATE,

The Synthite Laquer is here, the sleaving is here, just waiting on the mylar insulator sheet..... soon
Reply With Quote
  #6  
Old 05-30-2010, 11:55 PM
a31ford a31ford is offline
Registered-II
 
Join Date: Nov 2004
Location: Brandon, Manitoba Canada
Posts: 41
Likes: 12
Liked 20 Times in 8 Posts
Default Re: How-To, Exciter Rewind (both Stator & Rotor)

OK, Pictures to follow, BUT, here is the winding chart, it may look crazy but as we get into it, you will see why it looks like this, for now, we will have to wait for the photos as work has gone crazy for a bit, will update as I can.



a clearer copy can be had here:
http://pages.inethome.ca/a31ford/exc...ding-chart.htm

Greg
Reply With Quote
The Following 2 Users Like This Post:
  #7  
Old 06-02-2010, 10:42 AM
a31ford a31ford is offline
Registered-II
 
Join Date: Nov 2004
Location: Brandon, Manitoba Canada
Posts: 41
Likes: 12
Liked 20 Times in 8 Posts
Default Re: How-To, Exciter Rewind (both Stator & Rotor)

I just updated the chart (saw that the coil pic was missing, and also added a huge note about the windings at the bottom of the chart).
Reply With Quote
  #8  
Old 06-26-2010, 03:41 PM
a31ford a31ford is offline
Registered-II
 
Join Date: Nov 2004
Location: Brandon, Manitoba Canada
Posts: 41
Likes: 12
Liked 20 Times in 8 Posts
Default Re: How-To, Exciter Rewind (both Stator & Rotor)

NOTE: part 1 of the photo set.

Greetings All,

I know this has taken much longer that originally anticipated, and I appologize for that, but anyhow, here is some more info:

the wire is .046 (17 Ga.) used on the Exciter Rotor (on the Shaft )

I originally mis-read the wire size and had started winding it with 15 ga. (huge) as I started getting somewhere with it I realized that the there was problem, going back to the original wire I found it, and ordered replacement wire, SO, for the second time I am starting the re-wind......

The process is still the same, BUT, you will see that the photo's the first wire is considerably thicker, and then all of a sudden the photos look out of order, as there is only a couple windings on the rotor (where I re-start the winding process......)



Here is the original rotor, note bent and damaged windings in the forground.









Exposing the leads to the rectifiers and the "Y" (wye) connection.






Starting the process of mapping the windings........ (do not try this at home).




I know some people run dial-up connections, so I'll break the messages up for downloaing speed for them.


.
Reply With Quote
  #9  
Old 06-26-2010, 04:01 PM
a31ford a31ford is offline
Registered-II
 
Join Date: Nov 2004
Location: Brandon, Manitoba Canada
Posts: 41
Likes: 12
Liked 20 Times in 8 Posts
Default Re: How-To, Exciter Rewind (both Stator & Rotor)

NOTE: Part 2 of the photo set

Continuing On..


The Rotor has 36 slots, NUMBER THEM BEFORE you START !!!!


Breaking the laquer paint bond on the outer insulators (discard after removal)





insulators once removed, NOTE that the lower insulators are STILL inplace (we WANT to reuse these).





Me mapping the windings..... (this has been done for you, see chart at start of this message.) Note the broken laquer bits on the front of the vise.






The coil sets after the mapping process....

NOTE that if you look at the white set, starting from the left, the first two coils are wound clockwise (CW), the third is counter-clockwise (CCW), this is why there 2 sets of rectifiers on the rotor one set flows +, the other set flows -, because there is no actual wire connection, they use the 3rd winding as a "buck" winding to create the reverse flow for negative. this applies to each set of coils, and every third winding.




More to follow.
.
Reply With Quote
The Following 2 Users Like This Post:
  #10  
Old 06-26-2010, 06:10 PM
a31ford a31ford is offline
Registered-II
 
Join Date: Nov 2004
Location: Brandon, Manitoba Canada
Posts: 41
Likes: 12
Liked 20 Times in 8 Posts
Default Re: How-To, Exciter Rewind (both Stator & Rotor)

Note: this is the 3rd photo set.

Greetings all.

Continuing......


Notice the covering on the wire just under the screwdriver tip, I arbitrarily started with one coils' "end point" so to speak (this is where this coil comes out of the set) and had to "reverse wind" (unwind) the coils to see what and where it all happens. This starting point I called "one" (slot is above the number).







There is a "front" and "back" to the rotor core, the side with the threads for the rectifier screws, I called the front.




Because "one" was the starting point, "36" is the ending point, so when we reverse the un-winding, and start re-winding the new coils, we start at the last point and work are way back to one. (this is the reason why the winding chart starts at 36, I could have simply labled them the other way around (and should have) but WTH).




more to follow.

.
Reply With Quote
  #11  
Old 06-26-2010, 06:43 PM
a31ford a31ford is offline
Registered-II
 
Join Date: Nov 2004
Location: Brandon, Manitoba Canada
Posts: 41
Likes: 12
Liked 20 Times in 8 Posts
Default Re: How-To, Exciter Rewind (both Stator & Rotor)

NOTE: this is the 4th set of photos.

Continuing....



It REALLY, helps having a small scale to devide the magnet wire into 3 coils, the total on the rotor is about 1-1/2 lbs. (give or take) so 3 coils 1/2 lb. each should do it (it wouldn't hurt to be "heavy" on the wire, as the LAST thing we want to do is try and splice.....).

BTW, the white thing is a plastic tabacco can with a long bolt in the drill, I cut a slot at the top of the can, and twist a small loop into the wire, slide it into the slot and start winding, this takes some time, AS THE LAST THING WE WANT TO DO IS NICK THE WIRE......





I made a bunch of winding jigs from some vinyl tubing and some small steel tubing inserted in the vinyl tubing to hold it's shape on the rotor core.

BUT...I CHANGED to smaller rubber hose (windshild washer hose) and the wire from a coat hanger, as the others where too big for the new #17ga. wire.





I'm using a huge bolt, washers and 2 nuts, all bolted down tight on the core, so I can clamp the rotor in the vise without catching the wire on (or in) the vise..... ONE NICK IN THE WIRE"S INSULATION CAN CAUSE THE ENTIRE WINDING PROJECT TO FAIL !!!!!

Note the winding jigs.






END View, you can see the 3 sets of the windings starting ends (closest to the bolt, they are folded over), NOT all the windings are there yet, but this is where I figured out that there was a problem with using #15ga. Wire (to big), I have no idea how I screwed up on the guage, but the next post starts with the now correct #17ga. wire, and continues on from there.




More to follow.


.
Reply With Quote
  #12  
Old 06-26-2010, 06:55 PM
a31ford a31ford is offline
Registered-II
 
Join Date: Nov 2004
Location: Brandon, Manitoba Canada
Posts: 41
Likes: 12
Liked 20 Times in 8 Posts
Default Re: How-To, Exciter Rewind (both Stator & Rotor)

NOTE: This is the 5th photo set.

Continued.

After the wire guage screw up, and having to totally restart the process (OMG !) this is where I've ended up, 3 new sets of windings with a total of 12 coils on the rotor core, we are 1/3 of the way done, as the entire core holds 3 sets at 12 coils a set (hence 36 coils).

NOTICE that the coils are somewhat "droopy" in the middle part of the coil (when looking from the end or "front" view) this is to allow us to wind the 2 other sets of coils into the 2 slots between, all the coils overlap each other, and once all of them are in, the entire winding set is "Laced" with fiberglass winding cord, (VERY TIGHTLY) this is what holds it all together, and then it's dunked, but more info on that later.....

BTW, note the wire scraps that simply hold the loose ends, until I can get back to this project, these scraps are NOT part of the rotor.




until I can get back to this project...


.
Reply With Quote
The Following User Likes This Post:
  #13  
Old 10-03-2012, 06:34 AM
wiltaxis wiltaxis is offline
Registered
 
Join Date: Sep 2012
Location: Arezzo, Italy
Posts: 6
Likes: 4
Liked 0 Times in 0 Posts
Default Re: How-To, Exciter Rewind (both Stator & Rotor)

Hi a31ford I have just read with total admiration your thread on rewindind the exciter coils on your generator. You have given me the confidence to do the same.
I have an MDL4 16kva 50Hz 1500 rpm genny. I am at the stage where i have stripped and cataloged all of the coils as you advised and "hey presto" it seems to be identical to yours i am now obviously at the point of no return and have a question or two for you:
1 How do you recover the insulation that you took out of the top of the slot(with a hammer and washer) ?as i dont think i will be able to slide in a "U" section with the coils in place.
2 Do you have any more tips on the re assembly that you think may help someone as inexperienced as myself, but has managed to follow your passage and the brilliant chart you enclosed along with the photos.
Hope you can help me further and thanks for such an amazing post.
Kind regards
William
Reply With Quote
  #14  
Old 10-03-2012, 10:18 AM
Elden DuRand's Avatar
Elden DuRand Elden DuRand is offline
Subscriber
 
Join Date: Nov 2004
Location: Port St. Joe, Florida USA
Posts: 5,764
Likes: 7,477
Liked 4,033 Times in 1,785 Posts
Images: 6
Default Re: How-To, Exciter Rewind (both Stator & Rotor)

Greg:

What a project! I dunno if I'd have the nerve to try it ...... I'd prolly just send it to a motor shop for the rewind.

It'll be interesting to see how it works.
__________________
Take care - Elden
http://www.eldensengines.com
Reply With Quote
  #15  
Old 10-04-2012, 02:51 PM
wiltaxis wiltaxis is offline
Registered
 
Join Date: Sep 2012
Location: Arezzo, Italy
Posts: 6
Likes: 4
Liked 0 Times in 0 Posts
Default Re: How-To, Exciter Rewind (both Stator & Rotor)

Ok have finally finished the rewind not sure if i ever want to do another one.
It may sound daft but how can i test it before i reassemble the genny, can anybody tell me should there be a certain resistence? and the diods or rectifiers, what is the procedure Please help!!
Reply With Quote
  #16  
Old 10-04-2012, 07:32 PM
Jim Rankin Jim Rankin is offline
Registered-III
 
Join Date: Nov 2004
Location: Faunsdale, Alabama USA
Posts: 4,084
Likes: 42
Liked 1,106 Times in 882 Posts
Default Re: How-To, Exciter Rewind (both Stator & Rotor)

It's the same as a 3 phase motor stator, and as such it should rotate an aluminum can that is suspended over it with a thread. Can should fit around the outside of the armature when you put 3 phase power into it, it spins the can just like it would spin the rotor of a motor. If you don't want to do that, just check that each phase is connected to both the other two through the Y point with resistances approximately equal and no connection to the iron.

Now this thing is going to spin at 1800 rpm, so it must be well dipped and baked and the leads well laced so centrifugal forces don't shake them and eventually break the wires.
Reply With Quote
The Following User Likes This Post:
  #17  
Old 10-05-2012, 12:22 AM
Oldtech Oldtech is offline
Registered-I
 
Join Date: Aug 2010
Location: Saskatchewan Canada
Posts: 51
Likes: 29
Liked 17 Times in 12 Posts
Default Re: How-To, Exciter Rewind (both Stator & Rotor)

Great photos and description. My dad used to wind generators and motors. I never got that brave. Maybe lack of patience!!
Reply With Quote
  #18  
Old 10-05-2012, 03:00 AM
wiltaxis wiltaxis is offline
Registered
 
Join Date: Sep 2012
Location: Arezzo, Italy
Posts: 6
Likes: 4
Liked 0 Times in 0 Posts
Default Re: How-To, Exciter Rewind (both Stator & Rotor)

Thanks Jim i will certainly take your advice and bind and resign the windings as it dose spin 1500rpm (50Hz not 60)
I have not yet joined the three phases so that i can cheak them. Is there a way of calculating the resistence i should be getting on each circuit ?
Do you think that i can lead solder the "Y" joint or should i crimp them as they were ?
How do i cheak the "half moon" diode rectifier ?
Thanks again to all , such an imformative forum.
Reply With Quote
  #19  
Old 10-05-2012, 11:49 AM
len k len k is offline
Registered-III
 
Join Date: Jun 2012
Location: Manchester, New Hampshire
Posts: 5,699
Likes: 85
Liked 2,043 Times in 1,557 Posts
Default Re: How-To, Exciter Rewind (both Stator & Rotor)

You likely don't need it , but if you crimp them, might not be a bad idea to put some special grease on the wires before you crimp them to keep out moisture and corrosion, if you have some.
The grease I am thinking about is the type they use on connections in AC house circuit breaker boxs, like on the 100 amp wires. I never used it
Reply With Quote
The Following User Likes This Post:
  #20  
Old 10-05-2012, 07:09 PM
Jim Rankin Jim Rankin is offline
Registered-III
 
Join Date: Nov 2004
Location: Faunsdale, Alabama USA
Posts: 4,084
Likes: 42
Liked 1,106 Times in 882 Posts
Default Re: How-To, Exciter Rewind (both Stator & Rotor)

My opinion, clean the enamel off, twist together, slice a crimp band over it if you have one crimp and then solder the crimped joint. then slip some sleeving over it and lace it down. If you don't have the fabric insulating sleeving, I have used shrink tubing.

Same procedure on the opposite ends of the circuits, clean the enamel off the wires completely, slip on crimp band, insert flexible lead wire, crimp and then solder. Insulate with sleeving.

Checking a diode pack with several diodes in parallel is easily done as long as you have it disconnected from the rotor leads. Get an ohm meter or a meter with a diode check function, or you can use an AC test light as described in the old Onan manuals. Test each diode to the bridge, all 3 should conduct in the same direction and block in the opposite direction. Any that are different, probably should chuck them all and get new. Remember, each group of 3 should be all the same polarity.
Reply With Quote
The Following User Likes This Post:
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

F o r u m Jump

Similar Threads Chosen at Random
Thread Thread Starter F o r u m Replies Last Post
Rewind or Replace? mylesdw Generators & Motors General Discussion 105 08-05-2014 11:38 PM
Rust on stator and rotor reggie Onan Generators 1 10-02-2008 01:03 PM
Rotor Rewind panzerwillie Generators & Motors General Discussion 8 02-25-2008 11:51 AM
PM for rotor/stator...Miller/Onan TomMcnn Onan Generators 0 03-13-2006 10:04 PM
Rust proofing rotor/stator Arthur Generators & Motors General Discussion 5 01-23-2005 11:13 PM


All times are GMT -4. The time now is 09:27 AM.

Smokstak and Enginads site search!


All use is subject to our TERMS OF SERVICE
SMOKSTAK® is a Registered Trade Mark
A Community of Antique Engine Enthusiasts
Copyright © 2000 - 2014 by Harry Matthews
P.O. Box 5612 - Sarasota, FL 34277