Looking For a High-speed 3-phase 200V 400Hz Induction Motor 1

[Sparweb]

Looking for a suitable motor to replace the fan motor in a hydraulic oil cooler. The motor specified by the OEM is becoming scarce and/or prohibitively expensive. The motors are found on a ~40 year old aircraft that is going out of production soon. I expect more problems in the supply chain like this will be coming.

The fan is enclosed in a duct, so any growth of the motor diameter restricts the flow in the duct. The ideal motor would be found from off-the-shelf motors in production, rather than custom ordered. But we will consider a custom order if it doesn't need much NRE, and actually may ask for a unique part number for our use only. Quantities will be very low <10 units.

Specs:
Must operate on 3-phase 200 VAC at 400 Hz at least 10,000 RPM with at least 3.5 lb-in torque load.
My requirement is only about 0.6 HP continuous.
The current motor’s envelope is 2.5” OD X 4.0” long.
The shaft is 1.2” long x 0.312” diameter, with 2 set-screw flats.
The motor's case is completely sealed. No internal fan.
Rotation is counter-clockwise looking at the shaft end.
Needs an internal temperature protection switch with external wires to allow external fault detection.
I expect the air flowing through the oil cooler is normally <100 deg C, but may be much higher at times.
Wires coming out the side are easiest to deal with. Wires coming out the back end are next choice.
Wired in Star, with the Neutral on a 4th external wire. With the temp switch, total 6 wires needed.

Hopefully you can identify something that’s close to this.

We have tried Reuland Electric - too small for their product lines, so they would have to start from scratch.

I have been in touch with Montevideo Tech. They have a nearly perfect motor, but it is discontinued, and now they're pushing us toward a custom unit. I don't know if I can steer them back to my preferred path (make more of the old motor design, please). And they're struggling with some other communication-related things that should not be problems in the year 2020.

I am still running the phone-tag-e-mail obstacle course with the motor's OEM and their distributors. There may be hope that we were just misquoted, or they can supply an alternative themselves.

An old Eng-Tips post led me to an interesting Grundfoss pump motor with very similar spec's. If I had to take another product apart to get the motor I need, it would cloud the origins of the part, which is a no-no on aircraft. If anyone knows who makes the motors in the RediFlo2 pumps, I would like to talk to them.

http://www.sparweb.ca

 

[itsmoked]

Spar, spar, spar... What have you gotten yourself into?

My first thought is that the only thing that goes wrong with motors like this are the bearings or the pesky wire failing. This means the all important metal bits remain viable forever. A good rewinding shop can handle just about any motor. The issue is normally the cost to rewind small motors doesn't usually make sense against just buying a replacement because rewinding cost is at least about $6~700 these days. But up against the cost of a custom low quantity motor it will be a drop-in-the-bucket. Furthermore, any custom motor can likely result in prototype/adjustment cycles and if you think those are only the cost of a normal re-wind... you'd be wrong.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[waross]

Good point on the rewind Keith.I have no current data but many years ago the break even was 10 HP.
We rewound 10 HP motors for about the price of a new motor because we found that the rewinds stood up to severe and abusive use better than OEM winding.
Anything under 10 HP was part of the crews scrap copper Christmas party fund.
An exception was a smaller 2 HP motor that had a long lead time and was very expensive.
Looking for a replacement motor,
400 Hz / 60 Hz = 6.67
A 60 Hz motor fed 400 Hz will turn 6.67times as fast.
eg: 1750 RPM at 60 Hz = 11,700 RPM at 400 Hz.
Maximum safe voltage of a 230 Volt rated motor will be 230 V x 6.67 = 1533 Volts.
If you transform the voltage up to 1533 Volts you can multiply the HP x 6.67
Probably not in an aircraft. grin
But at rated slip and 6.67 times the Hz the hp will be 1/6.67 times rated.
By running higher on the slip curve you may be able to get to 1/3 times rated HP.
Going from wye to delta would take you to 1/1.73 times rated HP.
You can get the HP back by raising the voltage.
400 Hz transformers are a lot lighter than 60 Hz transformers. (About 1/6.67) That's why aircraft use 400 Hz.
Looking at this information and considering your need to identify the source, let's give Keith a star and investigate rewinding.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[Sparweb]

Don't you two know anything about "scope creep"? All I want is a nice cheap motor that fits perfectly in the spot for this old one, which that hasn't been made since 1980...

All right - more back-story because I can already tell this won't stay focused on the question I asked first. Still open to suggestions, please.

The motor has been disassembled and shown to need nothing but a new set of bearings. A little clean-up would also do it some good, but a re-wind is probably not necessary. The shop here is equipped to test the integrity of the stator, plus many other tasks common to component overhaul. There is room in the budget to re-wind the motor, but certainly not enough to have a custom job. Bearings is the #1 strategy here. Replacing the motor is #2.

There is a "but".

Standard practice on aircraft (so I'm told) is that bearings have a life. All bearings should be replaced at some interval, as I am sure you know.
The interval is based on speed, load, environment, material, etc. Well, this motor does not have a life at all. Let the thing run forever if it wants to.
The kicker is that if I replace the bearings, there is a high probability that some smarty-pants will insist that the bearings have a life. If I repair this motor by replacing the bearings, the subject of bearing life is right out there in the open. It's important to say that this motor failed when, you guessed it, a bearing seized.

This change would make the whole hydraulic oil cooler system go from a part that is serviced "on condition" (use it until it breaks) to a part that must be removed and overhauled on a regular schedule. Even if that schedule is 20,000 flying hours, or some enormous number that outlasts the aircraft itself, this is detrimental to the value of the overhauled hydraulic oil cooler. It will be worth 1/3 of a similar overhauled hydraulic oil cooler that doesn't have a life-limited part.

On the other hand, if I replace the motor with one that's slightly beefier, and can determine that the motor manufacturer uses the same ABEC class of bearing, possibly even the same bearing manufacturer, then I can show that the margin of safety on the formerly "infinite" bearing life of the previous motor just got better in the replacement.

Also note that the blower fan is one of 2 cooling methods for this hydraulic oil cooler (ram-air is the other) so fan motor failures are not a disaster, but a loss of redundancy.

I hope that sheds light on the reason I want to be able to procure an alternate motor. The bearing replacement strategy is cheaper, unless I can't prevent a bearing life replacement schedule. Then it becomes more expensive (in lost resale value) than the motor replacement option. If I can find a replacement off the shelf. Any suggestions?

http://www.sparweb.ca

 

[waross]

Can you avoid the "life" issue by sending the motor out for a rebuild?
"" and then replace it with a new or rebuilt motor?
A rebuild would entail replacing the bearings and inspecting and possible re-dipping and re-baking the windings.
Rather than your paper work showing a bearing replacement it would show a motor replacement.
Back to:
"(use it until it breaks)"
Maybe less chance of smarty-pants getting involved.
Even with a new motor installed is there a chance that "smarty-pants" will focus on the lifetime of the entire unit?

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[Sparweb]

This isn't my "oil cooler bearings" rodeo. I got bucked off last time.

Yes, the life issue could come up even on a new motor unit. But much less likely.
If I sent it out for a rebuild, that overhaul shop would need specific instructions that say "replace the bearing" among the rest of the things you list. Those instructions don't currently exist so we're back to generating the document myself. It's not any motor re-wind shop that can do work on aircraft parts, because they have to return it with a maintenance release form signed by someone authorized by FAA/EASA/Transport Canada. And for someone to do the authorized work, they need approved instructions. I am constrained by the rules and not looking for a way around them.

FWIW, I do plan to do a life estimate on the bearings as they are. Then make up my own mind if I am comfortable "owning" that analysis. If it gives me 10^9 hours, I will sleep well. If it gives me 10^4 hours, I will abandon this project altogether. I just don't want it to go farther than that.

http://www.sparweb.ca

 

[waross]

Thank you for your patience with us Steven.
I wish we could help, but I guess not.
I had some ideas about replacement motors but that would entail using a motor designed for an existing machine.
But;

which that hasn't been made since 1980...

With an over 40 year old piece of gear, you may have a lot of hours to use.
Any records available for time to replacement of motors when replacement motors were available?
Will a lifetime determination affect only this gear or will it affect all similar planes flying with this cooler?
Can a shop or perhaps the original maker accept generic instructions:
"Please re-manufacture and certify to original specs."?
I'm probably wasting your time. I'll shut up now.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[Sparweb]

Sorry. My emphasis was meant to be on the trouble I had last time I tried to deal with this kind of issue. I didn't mean to push back. My original question was a request for motor manufacturers that may fit the bill, and I'm still looking.

Any records available for time to replacement of motors when replacement motors were available?

There's the rub. The records are meticulously up to date and thoroughly substantiated for these aircraft from the OEM, and a schedule to inspect/replace/overhaul just about every component in the plane exists. This part is not one of them. I can confidently say that there is no existing replacement schedule for this motor, or the assembly it belongs inside, despite the evidence before me that they have bearings that may seize up. You just let it run until it stops.

Can a shop or perhaps the original maker accept generic instructions:
"Please re-manufacture and certify to original specs."?

Of course. That will be 24,000 USD please. When that price came back to us last year, we abruptly had to stop overhauling this equipment because the motors inside were suddenly beyond economic repair.

http://www.sparweb.ca

 

[waross]

Is this getting close?

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[Steven L. Reid]

Contact E und A Motors.

https://www.eunda.ch/en/

 

[Sparweb]

Thank you!

http://www.sparweb.ca