electric motor too slow

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Hello, everyone, and I'm sure I have a stumper nobody here has had to deal with yet!

My buddy refurbishes historic organs, many of which are motorized (the bellows and sometimes the mechanisms operating the pipes). In this case, we're talking about a motor that drives a fan that provides air pressure for a bellows.

The organ in question is a newer model, built in Europe about 100 years ago. The motor was dead, so he ordered a new one from a specialty company in Germany.

The motor arrived and, lo and behold, they built it to European specs-- 220 Volts supply and 50 Hz frequency.

So, just get a converter, right? Wrong. With a standard 220-110 converter, the motor turns far too slow-- he estimates 20% of its intended turning speed.

Naturally, the motor is also intended to work on three phases instead of one or two.

Anybody got any idea how the heck to fix this? The thing is sitting in the Cathedral Basilica of Philadelphia, assembled and unplayable.

Any help would be GREATLY appreciated.

--micheletrecaffe
 

Smart $

Esteemed Member
Location
Ohio
Site power system: ___ /____V _ ? _ W

Nameplate data of original motor...?

Nameplate data of replacement...?

FWIW, I don't believe there is any such thing as a 'standard' 220-110 converter, so that comment didn't help much.
 

kwired

Electron manager
Location
NE Nebraska
A 50Hz motor supplied with 60Hz will run faster then it is rated for.

Your story makes more sense if you were trying to run a 60Hz motor on 50Hz.

Care to provide us with more details so we can maybe help figure things out?


You did mention 220-110 converter, you sure you are not supplying 110volts to a 220 volt rated motor? That would work if supplying 25 Hz but motor would turn at half speed with half torque, but if at 50 or 60 Hz, you will have low torque (therefore low speed) and high current (which will overheat the motor) if the voltage is too low.
 

gar

Senior Member
Location
Ann Arbor, Michigan
Occupation
EE
150214-1446 EST

micheletrecaffe:

According to the site rules I don't believe a response would normally be provided. But I don't believe you know enough to be one to do the work.

You need to contact the proper type of electrician.

But I will make some statements.

If the motor was a universal type, then frequency is not a factor, only supplying the correct voltage, and that the pump (fan) was properly sized.

Assuming that the motor is an induction, and not a synchronous motor, then the design of the motor (rotor resistance) determines the speed-torque curve of the motor. In turn the motor speed is determined by the speed-torque curve of the load in combination with that of the motor. They have to balance at the operating point.

If the rotor resistance is low, and the torque load is constant, then speed is approximately proportional to frequency, and your motor would have run faster on 60 Hz compared to 50 Hz.

If the frequency is fixed, then speed is a function of rotor resistance and the mechanical load. Most induction motors have a fixed rotor resistance determined in the design process. Only wound rotor induction motors allow for speed adjustment in their application. A fan type application might have a motor with a designed high rotor resistance because of the characteristics of a fan type load.

You claim 3 phase, if so, then the motor on single phase would not have started.

Suppose the motor is really single phase, and you ran it on 1/2 voltage, then it would probably run slow or hardly at all, and might burn out.

Get a competent electrican to help you, and if they can not solve the problem, then have them contact the forum.

.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
150214-1446 EST

micheletrecaffe:

According to the site rules I don't believe a response would normally be provided. But I don't believe you know enough to be one to do the work.

You need to contact the proper type of electrician.
.

I agree. The mods probably should have closed this thread. It is fairly clear from your comments you are in over your head and need some competent help.
 

growler

Senior Member
Location
Atlanta,GA
You need to contact the proper type of electrician.

.



Yes and the people he needs to contact may not even be listed as electricians.

Here I would contact an electric motor shop that does rewinding and rebuild.

Just as a guess I would think they didn't tap the motor for the correct voltage if it's only turning at 20% normal speed and the multi-leads is whats making them think it's a three phase.

I kind of wish I was in the area I love antique equipment. Did a bunch of old printing equipment a few years ago, didn't make any money but had lots of fun.
 

Jraef

Moderator, OTD
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
But before it is locked, here is a possible scenario for you to consider with your qualified licensed electrician who has experience in such things.

Assuming an AC induction motor, by giving it 220V 60Hz you are under exciting the motor. AC induction motors are designed to provide a specific amount of torque based on the ratio of voltage and frequency applied, then the frequency determines the speed and the combo of speed and frequency is what we refer to as "HP". So that motor is deigned for a V/Hz ratio of 220/50 or 4.4:1. However you are now giving it 220/60 so the ratio is only 3.67:1. Motors are usually fine within +-10%, so it might have been OK at 3.96:1, but you are now way off of that. The consequence is that the motor will develop much less torque, around 70% of normal design torque. But the blower as a load is still going to demand what it needs, so even though the motor SHOULD be attempting to spin faster, it cannot spin that LOAD any faster, because it just doesn't have the torque to do so.

So what you are seeing is just the apparent lack of speed, but internally that motor is overloading at the same time and is under threat to be damaged. Stop experimenting and guessing, get some professional help.
 

sparkyrick

Senior Member
Location
Appleton, Wi
I'm working on a church remodel that was built in 1906 with a classic air organ. Fascinating stuff
rock.gif
 

Besoeker

Senior Member
Location
UK
Yes and the people he needs to contact may not even be listed as electricians.

Here I would contact an electric motor shop that does rewinding and rebuild.

Just as a guess I would think they didn't tap the motor for the correct voltage if it's only turning at 20% normal speed and the multi-leads is whats making them think it's a three phase.

I kind of wish I was in the area I love antique equipment. Did a bunch of old printing equipment a few years ago, didn't make any money but had lots of fun.
Probably cheaper to replace the motor with one that will work on the available supply and provide required power.
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
I have some motor shop contacts in the Philly area that may be able to help you. PM me if you're interested.

I once worked on a high pressure organ blower which was originally working from 240V, 60Hz using a non-NEMA motor with the impeller mounted directly on the motor shaft.
It failed by suddenly turning less than 1/4 speed.
It was a single phase capacitor start motor which would come up to speed fine if spun up with an external motor to the point where the centrifugal switch opened.
End result: Took it to a motor shop for rewinding the shorted start winding.
Working well for 30 more years now. Sounds like a miniature jet engine spooling up, so careful noise suppression on air inlet and outlet was necessary.
 

growler

Senior Member
Location
Atlanta,GA
Probably cheaper to replace the motor with one that will work on the available supply and provide required power.

delta or Y supply If the church has 208 the motor will run fine at 60 HZ to compensate for difference of 12 volt

And the 20% difference in frequency?


This is why I suggested going to a motor shop for help. Not to get the motor rewound but to find professionals that understand electric motors.

To find a motor that will run at the correct RPM and will operate at available power may not be all that's needed. A machine manufactured in Germany will probably be metric and an american replacement will have a shaft sized in English dimentions. maybe the shaft can be turned down or if it's belt drive they can use a different drive sheave ( not sure what all will neeed to be changed).

When I suggested a motor shop I just thought that's the best bet for finding someone that knows what they are doing. I'm sure there are electricians in the area that know all about motors but I have no idea how to find them ( most won't advertise as haveing experience with antique motors or equipment).
 
thanks to all

thanks to all

Hello, everybody who commented. I have not replied because my internet went out about two days after I posted. It just came back on tonight.So, just to be clear, I was NOT even DREAMING of trying to fix this problem myself. My friend is friends with the guy that maintains Wanamaker's organ here in Philly, and that's the biggest functioning organ in NAmerica. So that's where he went first for help. What he finally wound up doing was contacting a gent from Atlantic City who has loaned him a motor/blower....I would be interested in finding someone in the area experienced in these motors... our own attempts to locate someone failed miserably, in part because we were on short notice. Now that the immediate problem is fixed, it would be worth looking around and seeing if we can find someone who can make this baby work on our current. The motor itself is brand-new and was tested at the factory before shipping. Among other things, I understand they run them for 100 hours at full intended load to give the bearings a chance to 'break in'. They then re-calibrate and ship. Needless to say, the thing is also expensive-- upwards of $1000. Anyway, thanks again for all the imput.
 

kwired

Electron manager
Location
NE Nebraska
After reading OP again something I think we all missed is it appears he not only is trying to run a 50Hz motor on a 60Hz system, he also mentioned it is designed for three phase and he kind of indicates that it is supplied from single phase or possibly even two phase. If supplying a three phase motor with single phase - likely will not get any rotation at all, but connecting to a two phase source likely will give some rotation, just not going to give the motor what it is looking for so output will not be right either. It would be a little interesting to see just how the motor was connected if it is two phase supply but conected to a three phase motor. I think there is a two phase three wire system - that would be easy to connect and not realize you are not doing something wrong but a 4 wire system should leave you wondering what to do with the 4th lead and maybe give you a clue something isn't right.
 
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