Junkyard motors parade

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peskanov
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Post by peskanov » Thu, 04 Jul 2013, 11:28

Hi, it seems I can't resist the EV vice and now I am collecting items for a road legal car conversion!

My target is a 1200KG car with good aerodynamics. Maybe an Opel/Vauxhall Calibra, a Toyota Celica, a Mazda or a Ford Probe.

Again, my plan is a cheap conversion using a second hand Curtis and a rewound industrial AC. This means I am limited to ~100VDC, and probably less than 50HP peak.
Yep, I know this is little power for a 1200KG car, but it can be upgraded later to 80HP using another controller+more battery voltage and that's good enough for me.

That's was the base plan; now I am looking for and a junkyard AC motor who can reach peak 50HP (and hopefully 80HP ) in a 132 frame.
I have seen a few ones, and I would like your opinion about the candidates:
- ABB 7.5KW, 4 poles. Cos 0.88.
- Leroy Somer 9KW, 4 poles. Cos 0.85.
- AEG 11KW, 2 poles. Cos unknown.
- CEG 11KW, 2 poles. Cos 0.85.
- SOGA 9KW, 2 poles. Cos 0.87.

All of them weight 50-60KG and seem pretty much rust free. Maybe the CEG is heavier.

Here is a pic of the one I found more promising, the Leroy-Somer
Image

I can go to the junkyard again to check any spec, usually the motors remain there for a lot of time.
Thoughts?

Last edited by peskanov on Thu, 04 Jul 2013, 01:31, edited 1 time in total.

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Post by BigMouse » Thu, 04 Jul 2013, 15:04

Awesome! Chances are you'll have to get it re-wired anyway, so I'm not sure the polecount matters that much. In other threads, I think I've read it's better to start with a 4-pole motor, even if you're winding it to 4-poles again, due to them having more back-iron, though I could be mistaken. There's a thread somewhere on here with recommendations.

Either way, make sure you get one with an Aluminium frame.

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Post by a4x4kiwi » Thu, 04 Jul 2013, 18:16

Try and get one with foot and flange mount. It increases your mountung options to a gearbox and in a cradle.
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Post by Richo » Thu, 04 Jul 2013, 21:03

Yeah I'd start with the 4-pole.
Rewinding to a different voltage is easier than rewinding for different voltage and poles.
The 7.5kW would be fine.
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Post by peskanov » Fri, 05 Jul 2013, 00:09

Bigmouse,
logic says 4 pole motors should be heavier and have more back iron, but curiously Ivan Bennett says otherwise:
http://ivanbennett.com/forum/index.php?topic=2.0

"2 pole 3450 rpm, motors are likely to have more back iron."

I find it somewhat dubious, I am leaning towards 4 poles.

a4x4wiki,
Good call; I think only one of them has both flange and feet. I will have to check anyway.

Richo,
why the 7.5kw instead of the 9kw (Leroy-somer)? Both are 4 poles. Maybe you think the windings will be simpler?

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Post by BigMouse » Fri, 05 Jul 2013, 03:06

peskanov wrote: Bigmouse,
logic says 4 pole motors should be heavier and have more back iron, but curiously Ivan Bennett says otherwise:
http://ivanbennett.com/forum/index.php?topic=2.0

"2 pole 3450 rpm, motors are likely to have more back iron."
Ivan Bennett is the guy I was thinking of, I just mis-remembered which one was better. The number of poles should have a negligible effect on weight for the same frame size. It's essentially the same core, with the same amount of copper distributed differently. If there's any difference in the size of the stator, it would be made up for by the size of the rotor as the air gap will be about the same on all of them.

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Post by coulomb » Fri, 05 Jul 2013, 04:19

BigMouse wrote: ... I just mis-remembered which one was better.

I believe that 2-pole motors have more back-iron because they *need* more back iron; the magnetic path is longer, so you need the extra iron to prevent "magnetic voltage drop" across the long path, as it were. (MMF drop?)

So I don't think that 2 pole motors are to be favoured for the reason of the extra back iron.
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Post by peskanov » Fri, 05 Jul 2013, 12:41

To be fair, "2 pole motors have more back iron" is an ambiguous sentence.
More iron/kw?
More iron weight in relation to copper weight?
More iron for a given frame?

When I check motor specs in the inverterdrive shop, the heavier ones (for a given frame) are those having 4 poles. I think that's a good clue about this "back iron" mistery.

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Post by Richo » Fri, 05 Jul 2013, 21:00

I'm always a bit sceptical about odd-ball ratings.
9kW is uncommon.
Usually it means they have tweaked say a 7.5kW to get 9kW.
You may be lucky and it is just a long motor.
TBH until you have a Tm/Tn rating you'll be comparing oranges to oranges.
Just one might be rotten inside. Image

Looking at this:
http://www.leroy-somer.com/catalogue-in ... SES-en.pdf

A 9kW "NON-STANDARD POWERS" LSES 132 MU has Tm/Tn of 3.7 and weighs in at 68kg.
So on the face is probably good.
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Post by Richo » Fri, 05 Jul 2013, 21:03

The other 9kW FLSES 132 MR is 3.3 so still ok but is 88kg!

20kg of extra WHOA Image
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Post by Richo » Fri, 05 Jul 2013, 21:06

Most manufacturers have the options of different interchangeable fronts.
So don't get too hung up on the flange.
Just make sure you check they are available before buying the motor.
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Post by peskanov » Sat, 06 Jul 2013, 08:10

Well, after reading the 3.7 Tm/Tn spec, I couldn't resist the temptation and went for the Leroy-Somer. The guys at the shop tested it before selling it to me; it was not in working order, and the sold me it at scrap price: 60 euros (85 aud).

I am not sure the motor is the one in the catalogue, as it weights 60 KG (8 KG less). It looks nice, I will take the rotor to a motor shop to check the squirrel cage.
It seems the motor failed in the back side. The bearings are damaged, and the wires look slightly burnt. Front part looks like new.
Image
Front side is at the bottom of this pic:
Image
The back side of the rotor looks slightly cracked in the aluminium ring. Look like some heavy thermal cycling happened here:
Image
Front side ring looks like new:
Image
Windings:
Image
The rotor has 3 small cracks, the squirrel cage can be seen through them.
Image
Image

What do you think? Could the ring cracks be a problem in the future? I will post some detail pics of them after cleaning.
Last edited by peskanov on Sat, 06 Jul 2013, 03:19, edited 1 time in total.

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Post by peskanov » Mon, 08 Jul 2013, 03:32

Well, after some cleaning and closer inspection I noticed the "cracks" were not cracks at all. They are production defects:
Image
So no problem here. The little holes in the body of the rotor could have the same origin, but there were also a few metal pieces inside the motor (the flexible washer pressing the bearings was broken in pieces) so maybe there was some hitting and grinding.
It seems the rotor is in great shape, I will get the squirrel cage checked this week.

Now, I have a cautionary tale for anybody disassembling a motor.
The read end shield was removed quite easily, but the front one was not...The shaft+bearings refused to leave its housing no matter how hard did we hammer it.
After some attempts, we lost patience and stopped using wood between the hammer and the shaft...The obvious result:
Image
And here was the REAL problem:
Image
A segeer ring!
I have opened a few AC motors before, but none of them had a seeger ring. Fortunately we saw it before doing any serious damage to the motor. Of course, the shaft will need machining, but that was in the plan anyway...

BTW, I have not seen many 132 frame rotors before (only one in fact), but this one seems extra large as Richo suggested. It's about 21.5 cm long (little fins excluded).
Last edited by peskanov on Mon, 08 Jul 2013, 17:17, edited 1 time in total.

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Post by acmotor » Mon, 08 Jul 2013, 05:21

The internal circlip was not the reason the rotor was reluctant to come out of the front bearing.
The bearing was meant to stay in the front housing. It was retained by the circlip that was only accessable with a circlip tool once the rotor was removed. (and reverse for assembly)

I'd say the front bearing inner is rusted onto the shaft.
Hammers are not the go !
You need to visit a hydraulic press and possibly an oxy accetelyne type heat source to heat the bearing. If all else fails then use a knife disc on an angle grinder to carefully cut the bearing off.

Stator windings look OK from pic. May have been overheated in the slots though.
Do you plan rewinding the motor ?
Keep in mind this may all be a learning exercise and the motor may indeed only be worth scrap value.

Rotor is marked from the rubbing but probably OK.

One issue may be that the electrical isolation of the stator laminations may have been compromised by the aluminium rotor burnishing the inside of the laminations. May require careful cleaning to avoid eddy current flowing across the laminations.

edit: speln
Last edited by acmotor on Sun, 07 Jul 2013, 19:22, edited 1 time in total.
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Post by peskanov » Mon, 08 Jul 2013, 13:26

Mmm...the angle grinder solution is really tempting! Image

Yep, I have to rewind the motor for very low voltage. My controller is a Curtis 1238, just 100VDC.

My plan is to follow the steps of Ivan Bennet and rewind it myself. The stator has 48 slots, therefore I could use one of his schemes directly.
I have a pair of motor rewinding books, but I never got the strength to attempt it...now I can see Ivan's videos, it's much easier.
It's also good to know that old those wiring schemes Ivan is trying work...for better or worse, but they work!

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Post by BigMouse » Mon, 08 Jul 2013, 17:55

acmotor wrote: The internal circlip was not the reason the rotor was reluctant to come out of the front bearing.
The bearing was meant to stay in the front housing. It was retained by the circlip that was only accessable with a circlip tool once the rotor was removed. (and reverse for assembly)

I'd say the front bearing inner is rusted onto the shaft.
Hammers are not the go !
You need to visit a hydraulic press and possibly an oxy accetelyne type heat source to heat the bearing. If all else fails then use a knife disc on an angle grinder to carefully cut the bearing off.
I've never seen that in my experience. The bearings have always been press-fit to the rotor and slide-fit to the end bell. From the photo of the rotor still installed in the front end-bell, the circlip would have been accessible using right-angle circlip pliers. If he got it out without removing the circlip, then he's broken the retaining groove on the end-bell.

I agree about the laminations being burnished together. The laminations need to be electrically isolated from each other (on both the rotor and the stator).

Please document your re-wind process for us! I'm hoping to undertake my own re-wind on a stator in the not-too-distant future. Ivan's videos are very good. If only there were an easy reference for all the winding configurations they've tried, their ratings, and the results.
Last edited by BigMouse on Mon, 08 Jul 2013, 07:57, edited 1 time in total.

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Post by acmotor » Mon, 08 Jul 2013, 19:10

Yes, agreed, the circlip may have been accessible and likely the manufacturer's intention.

The pull the shaft method is also used for some (pre magnetised) PMAC otherwise assembly is near on impossible with the PMs grabbing the stator iron and pulling it off centre. Being able to feed the shaft through the bearing provides a centre guide for assembly.

Agreed also that the circlip groove is likely now damaged.

I think the bearing is more than press fit on the shaft if it can break the circlip out of its groove ! Image
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Post by peskanov » Mon, 08 Jul 2013, 22:09

Hey, we didn't break the circlip! We extracted it using patience and pliers.
Both the bearing and the circlip look good despite the silly hammering. Image

I didn't think laminations insulation could be a problem; if I understood my books correctly, the function of this (weak) insulation is to confine the eddy currents to short path inside each lamination. As the current will follow the least resistance path, a minimal insulation between sheets works.
When I take my multimeter and check for continuity on any magnetic core, I always get it. So, insulation is minimal, right?

BTW, the brushing of the rotor is pretty much superficial. I checked it using a ruler over the full length of the rotor, too see if I could see any height difference. I can't. Passing the finger over the surface, I can see the brushed part feels smoother; it feels a bit like plastic.

BigMouse, be sure I will document the process if I rewind the motor. Unfortunately everybody here (here in my city, not here in the forum) is trying to discourage me; they think I should take it to a profesional Image
Last edited by peskanov on Mon, 08 Jul 2013, 13:08, edited 1 time in total.

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Post by Johny » Mon, 08 Jul 2013, 22:19

My take on it is that
(the flexible washer pressing the bearings was broken in pieces)
caused the minor rotor damage. If it was bearing failure the damage would be more toward one end or the other (IMO).
Interesting stuff peskanov. I'm looking forward to your rewinding journey. I didn't really follow Ians's winding variations as I had always thought that there were not that many ways to rewind an ACIM - my limited understanding. Good stuff.

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Post by Richo » Tue, 09 Jul 2013, 00:14

What's the mini junction on the side of the motor for?
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Post by peskanov » Tue, 09 Jul 2013, 03:05

I have no idea, it has two of them. For external thermistors?

Well, I took the rotor to the shop: broken squirrel cage. Image
I am a bit disappointed cause I liked the shape/color of the motor, and that it had an extra oomph for a 132 frame...also, the paint, under all the grease, looked like new. Less work to be done!

Well, back to the starting point I guess. I will sell the LS and look at the other junkyard motors.

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Post by BigMouse » Tue, 09 Jul 2013, 05:34

That's a shame.

It's my understanding that the stator must be cooked at high temperature to burn off the lacquer so you can remove the old windings. This process strips the motor of its paint anyway.

The long rotor would have been a nice bonus though. Which motor is your second choice?

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Post by peskanov » Tue, 09 Jul 2013, 05:42

the ABB 7.5KW, as Richo said. Should be a safe bet (if it works!). I will check again the junkyard.

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Post by peskanov » Mon, 15 Jul 2013, 23:22

I decided to work a bit on the Leroy-somer before getting another motor. This week I will get the rotor to another shop for checking. It's probably broken, but I still have some doubts.
Plus, this motor is a good oportunity to develop some skills without breaking something valuable.

This weekend we extracted the old windings from the motor and learned a few things along the way.

First step was washing the motor. It was covered in old grease. Took about 1-2 hours to remove most of it using a generic household grease cleaner and a garden hose.
A look at the information plate, now clean:
Image
Next we disassembled the terminal box. Surprise!
Image
One of the cables was pinched by ones of the screws, causing a short to ground. Now we know why the motor tripped when the junkyard guys tested it.

Next, we cut the front heads using a small grinder. We used a cutting disc, very thin. Initially, the disc was too wide to enter the motor. We cut some old iron until the diameter was reduced a few milimeters.
Image
Windings after cutting.
Image
At this point we removed the small insulation bands using pliers (just the front ones).
Image


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Post by peskanov » Mon, 15 Jul 2013, 23:40

Next recommended step is heating the motor in an oven and extract the windings using a lever. I improvised a platform with an 800W electric resistance and tried to insulate the motor. It didn't work, too slow and probably too many heat looses.
Image
Another way to melt the varnish is using a gas torch. As we didn't have one, we tried with a hot air gun, working at 500C celsius (at the mouth of the gun of course).
Bingo! Heating a coil head for some seconds melt the varnish nicely. Using a screwdriver, we separated wires from the block until a coil head could be gripped firmly.
Using a long iron bar as lever we extracted the coils easily. No heat was necessary along the slots, working in the coil heads was enough.

The whole process including some failed methods (my "oven" and others) took about 4 hours.
Last step was extracting the main insulators. I just used an small screwdriver to push their heads out of the slot, and getting them out with pliers.
Image
And that's all. A nice, clean motor looking like new:
Image

We still have to count the wires in each slot (easier now we extracted the windings) and draw an scheme of the circuit. But we will wait until we have the rotor report.
Last edited by peskanov on Mon, 15 Jul 2013, 13:40, edited 1 time in total.

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