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Posted: 4/22/2016 12:57:52 PM EDT
One of my customer replaced a motor that burned up.  The old motor was a 20hp wired for 230v.  A vendor sold them a motor and when I went to wire it up I noticed the nameplate said 460v, no option for 230v.

I called the vendor, he did some checking and said yep, we sold the customer the wrong motor.

Here's the odd part:  The customer returned the motor and the vendor went inside and rewired it for 230v operation.

Customer took it upon himself to make the final connections to the motor and called me to say it didn't sound right when he bumped it so he wants me to stop by.

My first thought is the windings were sized for X amount of amps @ 460v.  Switching to 230 we are doubling the current.

Thoughts ?
Link Posted: 4/22/2016 1:11:08 PM EDT
Info overload, how about a model number?

If the manufacturer wont stand behind it, who is going to warranty it?
Link Posted: 4/22/2016 1:17:25 PM EDT
Most 3-phase motors allow for 208/240 & 480 connection. These motors have (9) motor leads brought out into the peckerhead. You have the option to wire for the low (windings in parallel) or high (windings in series) based on what voltage is being supplied. Any given motor will draw more amps at the lower voltage and less amps at the higher voltage. Power consumed stays the same.

It sounds like the replacement motor was wired/configured for low voltage (208-240) only based on what you describe. I assume that there were only (3) motor leads in the peckerhead? To rewire the windings for dual voltage, an end bell needs to be removed so that the internal winding connections can be changed to allow the windings to be configured/wired for 480v by the installer. That isn't generally done by a vendor/salesman as there are items that need to be done correctly such as insulating the connections, making the correct connections, balancing the rotor & NOT voiding the warranty by doing this.

Hard to troubleshoot via the Internet...
Link Posted: 4/22/2016 1:25:10 PM EDT
[Last Edit: 4/22/2016 1:25:30 PM EDT by garbageman]
There are only three leads in the peckerhead. The service in the building is only 230, there is no 460 option.

The the vendor that sold the motor went inside and somehow rewired it for 2:30
Link Posted: 4/22/2016 1:31:40 PM EDT
Photograph, and SHow us  the DATA PLATE...
Link Posted: 4/22/2016 2:38:53 PM EDT
Did you put an amp clamp on the leads?

I didn't think a 3 lead motor could be multi volt.
Link Posted: 4/22/2016 3:32:08 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By garbageman:
There are only three leads in the peckerhead. The service in the building is only 230, there is no 460 option.

The the vendor that sold the motor went inside and somehow rewired it for 2:30
View Quote



I would be apprehensive of that motor based on what you are saying...
Link Posted: 4/22/2016 3:39:56 PM EDT
From what I understand, if you tinker inside these things, you better know what the fuck you are doing.
Link Posted: 4/22/2016 3:45:39 PM EDT
[Last Edit: 4/22/2016 3:46:06 PM EDT by mancat]
Sounds like motor got upgrayedd. What's the problem?
Link Posted: 4/22/2016 3:47:32 PM EDT
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Originally Posted By joemama74:

From what I understand, if you tinker inside these things, you better know what the fuck you are doing.
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But it's Armature Hour.
Link Posted: 4/22/2016 4:02:13 PM EDT
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Originally Posted By RIP-Yataski:
Most 3-phase motors allow for 208/240 & 480 connection. These motors have (9) motor leads brought out into the peckerhead. You have the option to wire for the low (windings in parallel) or high (windings in series) based on what voltage is being supplied. Any given motor will draw more amps at the lower voltage and less amps at the higher voltage. Power consumed stays the same.

It sounds like the replacement motor was wired/configured for low voltage (208-240) only based on what you describe. I assume that there were only (3) motor leads in the peckerhead? To rewire the windings for dual voltage, an end bell needs to be removed so that the internal winding connections can be changed to allow the windings to be configured/wired for 480v by the installer. That isn't generally done by a vendor/salesman as there are items that need to be done correctly such as insulating the connections, making the correct connections, balancing the rotor & NOT voiding the warranty by doing this.

Hard to troubleshoot via the Internet...
View Quote


This, it's especially fun with old motors where the leads weren't properly labeled. In my case it was a 30hp around 30ft in the air. I really should have checked it out on the ground but ran out of time.
Link Posted: 4/22/2016 4:03:29 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By garbageman:
There are only three leads in the peckerhead. The service in the building is only 230, there is no 460 option.

The the vendor that sold the motor went inside and somehow rewired it for 2:30
View Quote



Did he check the rotation?
Link Posted: 4/22/2016 7:17:26 PM EDT
Rotation was correct.  The vendor that sold the motor and subsequently "modified" it to work with 230v did NOT change the nameplate.

When I bumped it I could instantly tell something was not right.  Put my amprobe around one of the wires and let the motor run for ~4 seconds and it was pulling ~350amps

Each leg was pulling about the same.    Not good.

So we pulled the motor from the machine and it worked just fine but that's with no load.

The motor connects to a centrifugal  clutch type assembly that transfers the connected load to the motor gradually so the motor doesn't see the entire load instantly.  

I'm thinking the motor now doesn't have the same HP since it's running on 230v.  The vendor swears it's putting out the same HP.

The worst part is the motor is a metric design and hard to find local.  One vendor was checking in Canada, the other was looking in Germany.  

Link Posted: 4/22/2016 7:20:27 PM EDT
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Originally Posted By California_Kid:


But it's Armature Hour.
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Originally Posted By California_Kid:
Originally Posted By joemama74:

From what I understand, if you tinker inside these things, you better know what the fuck you are doing.


But it's Armature Hour.


Ha, just caught that.  I'm thinking my customer got the "shaft" and he's a little "wound" up
Link Posted: 4/22/2016 8:15:52 PM EDT
Your customer sure the load is not having problems?
Link Posted: 4/22/2016 8:21:59 PM EDT
Metric?
probably 50 Hz,
Link Posted: 4/22/2016 8:30:11 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By garbageman:
Rotation was correct.  The vendor that sold the motor and subsequently "modified" it to work with 230v did NOT change the nameplate.

When I bumped it I could instantly tell something was not right.  Put my amprobe around one of the wires and let the motor run for ~4 seconds and it was pulling ~350amps

Each leg was pulling about the same.    Not good.

So we pulled the motor from the machine and it worked just fine but that's with no load.

The motor connects to a centrifugal  clutch type assembly that transfers the connected load to the motor gradually so the motor doesn't see the entire load instantly.  

I'm thinking the motor now doesn't have the same HP since it's running on 230v.  The vendor swears it's putting out the same HP.

The worst part is the motor is a metric design and hard to find local.  One vendor was checking in Canada, the other was looking in Germany.  

View Quote


Power (HP) is the same regardless of the voltage applied, assuming that it is wired properly for the voltage applied. Power is basically volts x amps. The ratio of volts to amps is such that the power consumed (work done or HP) would be about the same regardless of voltage applied...
Link Posted: 4/22/2016 8:59:37 PM EDT
Link Posted: 4/22/2016 9:27:39 PM EDT
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Originally Posted By ZW17:
Should have rejected the motor as soon as you noticed it was the wrong voltage.
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The customers sourced the replacement motor. I noticed that the nameplate stated 460 and brought it to the customer's attention. They chose to have the vendor rewire the motor and then the customer connected it
Link Posted: 4/22/2016 9:31:50 PM EDT
What is the difference in a motor "wound for" 240 and a motor "wound for" 240/480?  Are the windings a heavier gauge wire for the single low voltage due to the higher amperage demand?

I used to work in a Leeson factory but can't really recall any difference or if everything we made was dual voltage.  There were many different lead options on the various motors.

I also don't understand why popping an endbell to change the lead configuration would require rebalancing of the rotor.  The rotor is balanced before the motor is ever assembled.  Taking it apart doesn't change that.
Link Posted: 4/22/2016 9:48:18 PM EDT
Link Posted: 4/22/2016 9:50:49 PM EDT
Link Posted: 4/22/2016 9:55:35 PM EDT
[Last Edit: 4/22/2016 9:58:23 PM EDT by Kuraki]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By ZW17:


Wye vs delta
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Originally Posted By ZW17:
Originally Posted By Kuraki:
What is the difference in a motor "wound for" 240 and a motor "wound for" 240/480?  Are the windings a heavier gauge wire for the single low voltage due to the higher amperage demand?

I used to work in a Leeson factory but can't really recall any difference or if everything we made was dual voltage.  There were many different lead options on the various motors.

I also don't understand why popping an endbell to change the lead configuration would require rebalancing of the rotor.  The rotor is balanced before the motor is ever assembled.  Taking it apart doesn't change that.


Wye vs delta


Ah thank you.  It'll be the number of distinct winding circuits then.

ETA: I asked mostly because I have a unique 460v motor on a very old table saw I was hoping I could run on 230v, and then using a freq drive to change 220 1ph to 220 3ph.  It will definitely start and run on 230v with no load, I tried, but it's sounding like any load will make it suck amps and burn the winding insulation.
Link Posted: 4/22/2016 10:02:22 PM EDT
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Originally Posted By Kuraki:
What is the difference in a motor "wound for" 240 and a motor "wound for" 240/480?  Are the windings a heavier gauge wire for the single low voltage due to the higher amperage demand? No internal difference to the windings. The difference is in how they are internally connected. A nine lead motor allows the installer to apply (2) different voltages to it. Each voltage requires the nine leads to be connected in a different configuration. A three lead motor doesn't give you the option of dual voltage connection.

I used to work in a Leeson factory but can't really recall any difference or if everything we made was dual voltage.  There were many different lead options on the various motors.

I also don't understand why popping an endbell to change the lead configuration would require rebalancing of the rotor.  The rotor is balanced before the motor is ever assembled.  Taking it apart doesn't change that. I stated this poorly. The rotor of damn near any induction motor is actually made with laminated steel sheets with molten aluminum poured through holes in them. The rotor is than balanced before installing it inside the rotor. I meant to say something along the lines that the end bell needs to be reinstalled fairly precise so as to not cause the rotor and shaft to be out of alignment or to rub the stator.
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Link Posted: 4/22/2016 10:17:17 PM EDT
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Originally Posted By RIP-Yataski:

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Originally Posted By RIP-Yataski:
Originally Posted By Kuraki:
What is the difference in a motor "wound for" 240 and a motor "wound for" 240/480?  Are the windings a heavier gauge wire for the single low voltage due to the higher amperage demand? No internal difference to the windings. The difference is in how they are internally connected. A nine lead motor allows the installer to apply (2) different voltages to it. Each voltage requires the nine leads to be connected in a different configuration. A three lead motor doesn't give you the option of dual voltage connection.

I used to work in a Leeson factory but can't really recall any difference or if everything we made was dual voltage.  There were many different lead options on the various motors.

I also don't understand why popping an endbell to change the lead configuration would require rebalancing of the rotor.  The rotor is balanced before the motor is ever assembled.  Taking it apart doesn't change that. I stated this poorly. The rotor of damn near any induction motor is actually made with laminated steel sheets with molten aluminum poured through holes in them. The rotor is than balanced before installing it inside the rotor. I meant to say something along the lines that the end bell needs to be reinstalled fairly precise so as to not cause the rotor and shaft to be out of alignment or to rub the stator.



The motor frame should be machined to make that alignment for you.  All the motors we built were, anyway.  The endbells bearing journals and the shoulder are bored/turned in the same setup, the frame is counterbored to match that dimension.  

A good bit of my job was maintaining the die casting molds and equipment for the aluminum spray injection molders that made the rotors.  After they were shot, some were turned but not all.  Then they were heated in an oven and dropped onto the motor shaft, so they're heat shrunk on.  

I wish I'd picked up a bit more about motor design/assembly while I was there but I was the toolmaker and my work was predominantly elsewhere.

Winding machines What a goddamn headache.
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