# Evaporator fan motor problem



## erics37 (May 7, 2009)

Down at the fish plant they have several drive-in blast freezers. One of the smaller ones has two big evaporator fans. Both are 10 hp 3-phase 240. One of them is run off a standard starter, protected by 30 amp time-delay fuses. The other runs off a drive (they had to change the fan blades a while back because the old one broke and wasn't available anymore, so they had to put one in with a more aggressive blade pitch. They put the drive in to slow it down I guess).

Anyway for no apparent reason, the motor supplied by the standard starter, started blowing its fuses. I went to check it out. Megged the branch circuit conductors to each other and to ground, and megged the motor leads. All good. Hit start and the motor started up waaaaay heavy and settled in at about 45 amps. Waaaaay high for this motor; the identical motors in other rooms pull about 15 amps. Plus it's brand new.

Then the maintenance guy came by and I suggested we remove the fan blade and run the motor with no load. So we did, and switched it in. Started up nice and easy and settled in around 10 amps per leg. Perfectly fine!

Then we reattached the fan blade and tried again. Right back to really hard starting and running way hot. Clearly it is the driven load causing the issue, but I can't imagine why. The same fan blade has been there for years and has always run normally. And it's just one big chunk of metal. No joints or rivets or adjustable blades or anything. Obviously it can't have changed its own shape.

Any ideas?


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## wendon (Sep 27, 2010)

erics37 said:


> Down at the fish plant they have several drive-in blast freezers. One of the smaller ones has two big evaporator fans. Both are 10 hp 3-phase 240. One of them is run off a standard starter, protected by 30 amp time-delay fuses. The other runs off a drive (they had to change the fan blades a while back because the old one broke and wasn't available anymore, so they had to put one in with a more aggressive blade pitch. They put the drive in to slow it down I guess).
> 
> Anyway for no apparent reason, the motor supplied by the standard starter, started blowing its fuses. I went to check it out. Megged the branch circuit conductors to each other and to ground, and megged the motor leads. All good. Hit start and the motor started up waaaaay heavy and settled in at about 45 amps. Waaaaay high for this motor; the identical motors in other rooms pull about 15 amps. Plus it's brand new.
> 
> ...


No restrictions, ice, etc. in the evap? Otherwise I'd be suspicious of the motor. Bearings sound ok with no end play?


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## Cow (Jan 16, 2008)

I know you said the motors are identical but are you 100% sure it's the same RPM as the motor it replaced? Could it be the old one was 1725 and this one is 3450?

Also, did the problems start before or after the new motor?


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## sparkywannabee (Jan 29, 2013)

When you had the fan off did you turn the shaft by hand, and lift up on it to check for undercut.


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## triden (Jun 13, 2012)

Is it possible that the fan is somehow doing more work? For instance, maybe there was a restriction on the outlet or inlet before that made it draw less current. The current in a squirrel cage motor is proportional to the amount of work it's doing, so moving more air = more work = more amps.


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## varmit (Apr 19, 2009)

Did you check the basics: Is motor wired correctly? Could there be a phase loss or bad starter contact. A failed termination? If this problem only appeared after the new motor installation, check the motor RPMs. If there are no electrical problems the fan is most likely moving more air for some reason. 

It is always possible that a power, starter or connection problem killed the original motor and that problem still exists.


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## 8V71 (Dec 23, 2011)

sparkywannabee said:


> When you had the fan off did you turn the shaft by hand, and lift up on it to check for undercut.


This is an interesting thought. If it's a bladed fan it will put a lot of shaft pressure opposite of the air flow. Could there be mechanical binding inside the motor?


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## Southeast Power (Jan 18, 2009)

I had to read the OPs post twice.
I was kinda lead to believe that the motor with the drive was somehow affecting the other motor due to the load changing due to the new blade but, I realized that if they are evaporator fans, they just blow through coils. Not really much of a way they can work against each other unless there was some ductwork involved.
Then I saw the two words "brand new" this is the only thing that changed. Its a new motor with an unknown history at that site.
The change in load, I suspect, is a bearing or something loose causing a drag or wrong motor type.


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## tates1882 (Sep 3, 2010)

Are the blades installed correctly, ie not upside down?


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## JRaef (Mar 23, 2009)

I'll vote for bearing wear. OEM fans will often be designed to the bare minimums, including non-standard motors that take cost out by using very exacting engineering of things like bearings. If the replacement blades were even a little heavier, it could have hastened the end of life. Then if you think about it, the old blades were no longer made right? That means they were either really old, or the design was so bad to begin with they just cut their losses. So an original design error may have rendered those bearings almost useless before you replaced the blades, you are just witnessing the final death throes. Fan blades break because of vibration, the vibration that caused it to break May have been the first warning sign of a failing motor bearing. The fact that you could spin it with no blades doesn't mean they were good, because without the blades there was no axial load.


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## dronai (Apr 11, 2011)

Besides all the things already said, you are there only to solve the problem, but didn't do the installations. Sometimes the maintenance people don't give you the whole story of what they did. 

But like post #6 Varmit said "It is always possible that a power, starter or connection problem killed the original motor and that problem still exists. "


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## John Valdes (May 17, 2007)

Eric. Are you certain this new motor is apples to apples to the old one?
For example a 10 hp motor for a centrifuge would not work on a normal application.
All the specs would be the same except for the "Design" code. ( Limits of Torque).

If the motor is exact without any further question, you need to check every connection to this motor next. A high resistance connection will read the proper voltage, but should go to zero when a load is presented.
Bus duct stabs and sockets are bad for this as they are not normally suspected. Also breakers, starters and overload contacts.
Have you checked current during the averse condition? All three legs during start up and eventual run?

You did say fuses and not overload tripping right?

Lastly. I know you hate to do this, but if you cannot find any issue with the motor or its wiring and or connections, I would swap out a known good motor doing this exact same job if possible.
If the problem follows the motors, then its not the motor.

And make damn sure this new motor is the same as the one they took out. Check the design letter or code to see.


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## wdestar (Jul 19, 2008)

Can you send a schematic of the circuit? I know, it may sound stupid, but one never knows.

My gut feeling is that: 1. the fan blade is either dirty, out of balanced or warped. 2. The variable drive fan motor or drive is back-feeding an inbalance to the other.

Just guesses.


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## micromind (Aug 11, 2007)

This may be a ways out in left field, but here goes anyway. Lol.

Are the two motors a long distance from the source, and fairly small wire?

The reason I ask is because the input to every VFD is a switching power supply, and by their very nature, they will cause distortion of the sine wave of their feeders. 

Since a motor operating directly across the lines is a reactive device, it will see distorted waveforms as mostly input power, but the distortion will be seen as an opportunity to become a generator and attempt to correct the distortion. 

This will cause higher current to be read and therefore, more heat in the stator. 

A line reactor on the input side of the VFD will help a lot, but only if a distorted wave is the actual problem. A scope will tell you how much the VFD is screwing with the other motor. 

Yes, this is a longshot at best, I seriously doubt if a distorted wave could cause the amount of current you're seeing, but if you have access to a scope, it'd be worth it to see. 

The more likely possibility is, as noted, bearings. It takes very little slop in motor bearings to cause the rotor to be misaligned with the stator, and this will always result is high current and low HP. And growling, especially during starting. 

Pay close attention to inward/outward play in the bearings. A 10HP fan will place roughly 30lbs. of thrust on the shaft either inward or outward, depending on the direction of airflow. If you push in or pull out the shaft with 30 lbs of force, and it moves in or out, there's your problem.


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## erics37 (May 7, 2009)

wendon said:


> No restrictions, ice, etc. in the evap? Otherwise I'd be suspicious of the motor. Bearings sound ok with no end play?


The motor and blades are not frozen over. Ice buildup on the evap coils would restrict air flow and reduce current flow for the motor as it is doing less work (moving less air). It is all on a periodic defrost timer cycle anyway.



Cow said:


> I know you said the motors are identical but are you 100% sure it's the same RPM as the motor it replaced? Could it be the old one was 1725 and this one is 3450?
> 
> Also, did the problems start before or after the new motor?


Honestly I never saw the original motor. Maintenance guys noticed fuses blowing on the old motor and just replaced it with a brand new one. New one is 1725, I presume the old one was as well.



sparkywannabee said:


> When you had the fan off did you turn the shaft by hand, and lift up on it to check for undercut.


Yes, it spins freely.



triden said:


> Is it possible that the fan is somehow doing more work? For instance, maybe there was a restriction on the outlet or inlet before that made it draw less current. The current in a squirrel cage motor is proportional to the amount of work it's doing, so moving more air = more work = more amps.


Hard to say. Long story short: same old fan blades on a brand new motor.



varmit said:


> Did you check the basics: Is motor wired correctly? Could there be a phase loss or bad starter contact. A failed termination? If this problem only appeared after the new motor installation, check the motor RPMs. If there are no electrical problems the fan is most likely moving more air for some reason.
> 
> It is always possible that a power, starter or connection problem killed the original motor and that problem still exists.


Motor wired correctly. I shut it off and locked it out and went in to the freezer (f*ck that was cold), took apart the peckerhead and megged the motor right there. Also megged the conductors L-L and L-G. Put it all back together myself.

The circuit originates about 30 conductor feet away from the motor. Dead simple. Taps off a motor feeder into a fused disconnect, from there right into a starter box, and then a straight shot to the motor. No local disconnect :whistling2: no splices, straight home run.



John Valdes said:


> Eric. Are you certain this new motor is apples to apples to the old one?
> For example a 10 hp motor for a centrifuge would not work on a normal application.
> All the specs would be the same except for the "Design" code. ( Limits of Torque).
> 
> ...


As I mentioned, I never saw the original motor. All I can assume is that the maintenance guys order motors all the time and they know what to get.

The goofiest part is that there are no overloads :blink: The starter enclosure has an external reset button like it USED to have a starter in there, but somebody took it out and replaced it with just a contactor. When I had the fan blade off and the motor was running nice and steady, I did a FOP test on the starter (well, contactor) and it measured almost as good as a brand new set of contacts. It wasn't drawing full load however. It stays on almost all the time and doesn't get very many open/close operations.



wdestar said:


> Can you send a schematic of the circuit? I know, it may sound stupid, but one never knows.
> 
> My gut feeling is that: 1. the fan blade is either dirty, out of balanced or warped. 2. The variable drive fan motor or drive is back-feeding an inbalance to the other.
> 
> Just guesses.


The drive is a separate circuit feeding a separate motor entirely. The fan blade is fine.



micromind said:


> This may be a ways out in left field, but here goes anyway. Lol.
> 
> Are the two motors a long distance from the source, and fairly small wire?
> 
> ...


The fan on the drive is operating fine; the other non-VFD fan is the one with issues.

So sounds like the consensus is bearings huh? It's the only thing I can think of that would cause this issue. But why the hell did it start acting like this when they still had the OLD motor in place??

The overcurrent issue is steady and even on all 3 phases. There isn't one leg in particular that's over-amping. Clearly it's a load issue, which could be argued to include gnarley bearings. But really? Brand new motor, right out of the box, with sh!tty bearings?


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## varmit (Apr 19, 2009)

From your detailed description of the problem, I would say that the original motor failed for unknown reason(s). The new motor seems to have some internal winding problems, either some windings open or or some windings shorted (not to ground) causing, in either scenario, an increased current draw.

Just because something is new is meaningless anymore. i have "out of the box" failures all of the time.

Did you check the all three phases for proper voltage while running and off?


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## sparkywannabee (Jan 29, 2013)

Baldor motors are quality product, never had one fail out of the box. Years ago we were changing a 3 ph motor on top of a big oven, I tried to hand it up, should have used a boom truck, dropped it, it never did work right, kept tripping the breaker if i recall, had to end up getting another new motor. Of course, don't expect the maint guys to fess up in a hundred million years. We don't fess up to nuttin.


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## John Valdes (May 17, 2007)

Eric. Is the fan blade attached directly to the motor shaft or is the motor turning an assembly? Pulleys and belts?

I assumed it was direct drive, but now I am not sure. If its not direct drive, its time the mechanical aspect of this problem is addressed.
You can prove this with another motor. A swap out. If replacing the motor does no good, then for sure its a mechanical issue. And in some cases out of your hands and into the hands of the maintenance mechanics.


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## gesparky221 (Nov 30, 2007)

When I worked in a meat packing plant we had to order special motors to run in our blast freezers. The freezer was kept at -40. You had to wear a cold suit to work in there. If I rememeber correctly it had something to do with the type of grease in the motor bearings. But that was over 30 years ago and I don't remember what the spec was. But I do remember ordering special motors to use in this application. I had to swap a bad one out and it took several weeks to get a replacement


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## erics37 (May 7, 2009)

John Valdes said:


> Eric. Is the fan blade attached directly to the motor shaft or is the motor turning an assembly? Pulleys and belts?
> 
> I assumed it was direct drive, but now I am not sure. If its not direct drive, its time the mechanical aspect of this problem is addressed.
> You can prove this with another motor. A swap out. If replacing the motor does no good, then for sure its a mechanical issue. And in some cases out of your hands and into the hands of the maintenance mechanics.


Direct. Fan blade mounted right on the motor shaft.


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## Galt (Sep 11, 2013)

What if you turn the motor with the drive off and try it? Or take the motor apart and check things over. Sure sounds like a bearing problem.make sure to let us know what you find. Thanks!


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## erics37 (May 7, 2009)

Galt said:


> What if you turn the motor with the drive off and try it? Or take the motor apart and check things over. Sure sounds like a bearing problem.make sure to let us know what you find. Thanks!


The motor in question is not on a drive.

This particular freezer room has two fans, each with their own motor. As I mentioned earlier, one fan motor got replaced a couple years ago and in the process, they somehow broke the fan blades and had to order new ones. The original style was no longer available, so they installed a different fan blade with a much more aggressive pitch. They put that one on a drive in order to slow it down. That one has been working great and still works great.

The other fan is the one in question. It is not on a drive, never has been, and up until recently has been working fine for years and years. The previous motor started blowing fuses, so they ordered a new one and changed it out (supposedly identical), but the new one seems to be suffering the same problem of drawing high current.

Megged the wires and motor, all good. Ran without fan blades attached, all is nice and mellow. Reattached fan blades, all f*cked up. Conductors are a direct home run with no splices. Voltages are good during run (without fan blades), FOP on contactor and disconnect revealed no compromised switching contacts. I can't completely rule out some sort of weird conductor issue, and given that it's only 30 feet away I might consider running new wires to it anyway. Would be quick and easy. But I really don't think that is the issue.


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## micromind (Aug 11, 2007)

Did this occur shortly after the VFD was installed, or was it a long time after?

As I stated in my previous post, it's possible that the VFD is screwing up the waveform on the input side. All VFDs will cause line side wave distortion, the question is will it be enough to cause trouble with the motor operating across the lines. 

The motor driven by the VFD will run fine; it's being supplied by the output of the VFD. The amount of waveform distortion on the line supplying the VFD has no effect on its output. 

Seriously though, this is a longshot at best, but it'd be worth running the across the lines motor with the VFD motor not running.


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## erics37 (May 7, 2009)

micromind said:


> Did this occur shortly after the VFD was installed, or was it a long time after?
> 
> As I stated in my previous post, it's possible that the VFD is screwing up the waveform on the input side. All VFDs will cause line side wave distortion, the question is will it be enough to cause trouble with the motor operating across the lines.
> 
> ...


I don't think that is the issue. Throughout our testing, the motor on the VFD was off and the drive was even actually powered down, but the motor in question was still acting up. Furthemore, this drive has been there for several years and this issue only popped up in the last few weeks.


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## Going_Commando (Oct 1, 2011)

sparkywannabee said:


> Baldor motors are quality product, never had one fail out of the box. Years ago we were changing a 3 ph motor on top of a big oven, I tried to hand it up, should have used a boom truck, dropped it, it never did work right, kept tripping the breaker if i recall, had to end up getting another new motor. Of course, don't expect the maint guys to fess up in a hundred million years. We don't fess up to nuttin.


I had a bad Baldor motor fresh out of the box on an exhaust fan in March. Brand spankin new.


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## erics37 (May 7, 2009)

Going_Commando said:


> I had a bad Baldor motor fresh out of the box on an exhaust fan in March. Brand spankin new.


What was bad about it?


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## micromind (Aug 11, 2007)

erics37 said:


> I don't think that is the issue. Throughout our testing, the motor on the VFD was off and the drive was even actually powered down, but the motor in question was still acting up. Furthemore, this drive has been there for several years and this issue only popped up in the last few weeks.


Figured it was a longshot anyway.....lol.

If the bearings are good, it's possible that the stator is ok but the rotor has an open or shorted winding. 

The only way I know of to determine this is with a growler. Most motor shops have one and it'll tell you right away if the rotor is good or not.


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## Big John (May 23, 2010)

I keep typing and erasing replies as I re-read and discover that it's already been addressed. This is a good one.

Is it possible you have one hell of a coincidence and two motors went bad in unrelated yet identical ways? I guess, but man....

The only thing I can say at this point is that I would not re-pull the conductors. Absolutely nothing points to the conductors being bad and everything points to them being good. I think that's a waste of your time and their money.


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## erics37 (May 7, 2009)

Big John said:


> I keep typing and erasing replies as I re-read and discover that it's already been addressed. This is a good one.


This seems to be the general consensus :laughing:



> Is it possible you have one hell of a coincidence and two motors went bad in unrelated yet identical ways? I guess, but man....


I'm not much for weird coincidences like that but maybe god doesn't want us to harvest Pacific Whiting anymore?



> The only thing I can say at this point is that I would not re-pull the conductors. Absolutely nothing points to the conductors being bad and everything points to them being good. I think that's a waste of your time and their money.


I tend to agree. It might just be to the point where I say, "Okay you know that brand new motor y'all have in there? We need another motor." That's gonna sound bad.


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## Big John (May 23, 2010)

Eric, remember this one where Marc was burning up a MCP and it turned out he had pin-holes in his branch wiring?

I'm batting zero here, because I couldn't explain that one, either. But maybe that's your ammo for a conductor swap. "Well, I've heard of something like this before...."


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## erics37 (May 7, 2009)

Big John said:


> Eric, remember this one where Marc was burning up a MCP and it turned out he had pin-holes in his branch wiring?
> 
> I'm batting zero here, because I couldn't explain that one, either. But maybe that's your ammo for a conductor swap. "Well, I've heard of something like this before...."


Yeah I remember that thread. The conductors here are regular THHN/THWN/whatever. Maybe the conduit is full of ice or something. Like I said, it's a quick and easy and short pull. I might just pull new wires for the hell of it, and also put in a proper starter.


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## John Valdes (May 17, 2007)

erics37 said:


> I tend to agree. It might just be to the point where I say, "Okay you know that brand new motor y'all have in there? We need another motor." That's gonna sound bad.


You can prove its the motor by swapping out the one thats on the drive.
I would not buy a new motor until I was certain it was the motor.
I would also check with the OEM and make sure they bought the right motor!

I would not touch the wiring as you have already proved them to be good.

Changing out this new motor is the only thing you have not done. I think its high time you did.
And please let us know what you find out.


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## Cow (Jan 16, 2008)

I have one thing to try but I don't know how much you want to mess with this thing.

So if I understand this correctly you have two different evaporator fan motors, call them fan motor 1 and fan motor 2.

Fan motor 1 is a VFD driven 10HP with a steeper pitched fan that must be driven slower to keep from going into an overcurrent situation.

Fan motor 2 is an across the line 10HP with a supposedly original fan setup capable of being driven by a 10HP.

Since you seem to be learning towards a bad motor, you could just replace it to rule it out, it's only a 10HP. They aren't that expensive. If it turns out it's not the motor, they have a spare, which isn't a bad thing.

But if you wanted to try something before you start replacing parts here's something I might try if it's possible. On motor 1, run it up to the motor current limit and note the speed or Hz it runs at. Swap the blades from motor 2 to motor 1. Run motor 1 again, if motor 2 truly has a problem, motor 1 should be able to hit 60hz with no current issues. If it hits 60hz and is pulling around 45 amps just like 2, you know you have too big of a fan.


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## erics37 (May 7, 2009)

Cow said:


> I have one thing to try but I don't know how much you want to mess with this thing.
> 
> So if I understand this correctly you have two different evaporator fan motors, call them fan motor 1 and fan motor 2.
> 
> ...


Also a good idea. I'm writing all these down :laughing:


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## micromind (Aug 11, 2007)

Depending on the general layout, it might be easy to run wire or a cord from the VFD to the bad motor and see what happens when it's run with a VFD. 

If possible, I'd run the wire from the VFD output to the bad motor starter output.


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## denny3992 (Jul 12, 2010)

I would add the ol block, maybe its a thermal ol issue the brkr is seeing and not an over current? 

Then its either a winding issue or bearing 

My 2€


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## ponyboy (Nov 18, 2012)

denny3992 said:


> I would add the ol block, maybe its a thermal ol issue the brkr is seeing and not an over current? Then its either a winding issue or bearing My 2€


That's usually the type of failure I see. But if he didn't see any voltage drop across the contacts I don't know where else the heat would be coming from.
Eric, is this motor turned on once a day or several times a day. We had an exhaust system once throwing fits because the operators were shutting down a fan when they shouldn't have been. It was only designed to be started once a day but the excessive across the line starts in short proximity weakened the thermal in the cheap iec parts


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## erics37 (May 7, 2009)

denny3992 said:


> I would add the ol block, maybe its a thermal ol issue the brkr is seeing and not an over current?
> 
> Then its either a winding issue or bearing
> 
> My 2€


There is no overload block. There should be, but there isn't.



ponyboy said:


> That's usually the type of failure I see. But if he didn't see any voltage drop across the contacts I don't know where else the heat would be coming from.
> Eric, is this motor turned on once a day or several times a day. We had an exhaust system once throwing fits because the operators were shutting down a fan when they shouldn't have been. It was only designed to be started once a day but the excessive across the line starts in short proximity weakened the thermal in the cheap iec parts


It pretty much runs 24/7, 365 days a year. Not sure if the defrost timer kills the evap fans at some point but I doubt it. I still don't have my brain wrapped around all the HVAC/R stuff.


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## JRaef (Mar 23, 2009)

erics37 said:


> There is no overload block. There should be, but there isn't.


Something I just ran across in an evaporator system used in a cold room last week. They are getting multiple rapid motor failures, either bearings or insulation, 20 motors out of 80 in just 3 months from the initial installation, 5 in one day last week, the day after I left the site to investigate.  

All of them use a Baldor motor that is 3phase, but has an INTERNAL Klixon thermal cutout, something I don't see on 3phase motors very often. That by the way is why it is legal for them to not have an external OL relay, apparently this is really common in the evap industry because they want it to automatically reset and the evap fans are generally in the ceiling where nobody is around them. The motor is Wye wound internally, and the Kilxon switch is in the Wye point of all 3 windings, so if it trips, it opens all 3. 

When the evaps ice up, it stalls the motor and the Kilxon trips, then resets when it cools off and it does it again, over and over and over. Nobody notices because without an OL relay that has to be manually reset, you have no idea it is happening unless someone happens to see that the fan stop moving. And then because there are multiple fans, it moves anyway because of windmilling. The way I figured it out was to put a recording meter on it and look at the current. It was tripping off 6-8 times per day. That HAS to be hard on the windings, bearings etc. I think that because the Klixon is outside of the stator in the connection box, the cold air is making it reset too soon, before the rest of the insulation and bearing grease can cool down too, so the multiple re-starts are causing damage. I'm going to have external OL relays installed and although they insist on them being auto-reset because they don't want to lose product, I can at least wire an aux contact to an indicator and a PLC input to track how often they are tripping, so maybe they can pay closer attention to the icing situation.


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## Big John (May 23, 2010)

Where's he getting the 45A running current? For a 10HP motor I would expect somewhere in the neighborhood of 24A FLA and he says that running load on other identical motors is only 15A.

That don't sound like a thermal or short-cycling issue to me. Everything I'm reading says "driven load problem." I am just at a complete loss to explain what could possibly be wrong with a direct-mounted fan blade that used to work fine.


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## JRaef (Mar 23, 2009)

I'm still thinking the bearings are damaged. A couple of the ones that failed in my system had bad bearings, I think because they are getting cooked from the heat of restarting so often. They are TENV motors, so that means the rotor heat has to go out through the shafts.


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## John Valdes (May 17, 2007)

Big John said:


> Everything I'm reading says "driven load problem." I am just at a complete loss to explain what could possibly be wrong with a direct-mounted fan blade that used to work fine.


Same here. I still think he should contact the OEM and make sure this motor they installed has the right Design designation.

The only thing that has changed in this scenario is the motor. Same controls. Same fan assembly and the same wiring.

The reason I am stuck on this design letter is due to an issue I had once a several years ago.
I had a customer call me one morning early needing a replacement motor.
I took all the motor nameplate from him and proceded to get one off the shelf at the shop.
He asked me if I was sure this motor would work and I assured him it would.
It lasted all but one day.

Turns out, the motor was special and had a special torque rating that I ignored. The "design letter" or "code" was different than the standard motors we stocked.
I called the OEM (original motor already tossed) and they informed as to why my motor would not work in that particular application.
I ended up ordering one from them at 5 times the cost of the one I provided. As far as I know, it could still be running today.

So, Eric. At least check on this. Might not be the issue, but it cannot hurt to check. A simple phone call or find another way to determine what was engineered for this application.
The addition of the drive to the opposite motor may have more history than you actually know. There could be more than one reason for this drive! 
Call the OEM and make certain.

I bet those maintenance guys know more than they are letting on.
They told you about the fan and I bet they might even know what the issue is?


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## sparkybrian (Jul 7, 2014)

My guess is one phase has a loose/hot connection and under load there is a large voltage drop.


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