# medium voltage motor rotation



## Boneshaker (Jul 31, 2009)

13000 horse power?


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## rlb0319 (Sep 1, 2009)

That is correct. 12kv


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## MDShunk (Jan 7, 2007)

rlb0319 said:


> does anyone have a suggestion as to verify rotation before we hook up the leads.


If it doesn't have something like "A-B-C Clockwise facing shaft end" noted in the motor paperwork, you might have to get primitive and spin it by hand with a rotation meter hooked up.


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## user4818 (Jan 15, 2009)

MDShunk said:


> If it doesn't have something like "A-B-C Clockwise facing shaft end" noted in the motor paperwork, you might have to get primitive and spin it by hand with a rotation meter hooked up.


Or just hook it up, see how it spins and then change it if necessary? Probably easier said than done with 15 KV rated cable. :laughing:


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## rlb0319 (Sep 1, 2009)

The motohas to turn CW due to it is currently connected to a compressor. The power leads are being replaced along with the VFD. I am trying to figure a way to make sure I have a CW rotation when I connect my leads.


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## MDShunk (Jan 7, 2007)

Peter D said:


> Or just hook it up, see how it spins and then change it if necessary? Probably easier said than done with 15 KV rated cable. :laughing:


Depending on how cramped the wiring compartment is; yes, sometimes easier said than done. A guy could always sacrifice a set of elbows and hook them up long first, to see which way it goes. That's sorta rookie, though.


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## MDShunk (Jan 7, 2007)

rlb0319 said:


> The motohas to turn CW due to it is currently connected to a compressor. The power leads are being replaced along with the VFD. I am trying to figure a way to make sure I have a CW rotation when I connect my leads.


OOOhhh... Then someone seriously F'd up when they didn't mark things before they torn it down to put in the VFD. If you put it all back the same way, the VFD will have you spinning the right way. There's really no harm in having the compressor spinning the wrong way for a little bit. You'll see the gauge start to go backwards. No biggie. The only time this is a big deal is with a rotary vane compressor, but you're probably dealing with a screw compressor if it's that big. Those same compressors serve vacuum duty too, and it might even have a phase reversal relay if it's got some feature that would break if it ran backwards.


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## user4818 (Jan 15, 2009)

What type of facility requires a 13,000 HP air compressor? Glass bottle plant?


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## Bob Badger (Apr 19, 2009)

Peter D said:


> What type of facility requires a 13,000 HP air compressor?


It's what I use to inflate my head.


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## MDShunk (Jan 7, 2007)

Some industral parks have a central compressed air location, and they resell it to each tenant and meter it like a utility.


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## drsparky (Nov 13, 2008)

This question is also posted in tool and equipment section.


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## user4818 (Jan 15, 2009)

Bob Badger said:


> It's what I use to inflate my head.


:lol:

Nah, I think you need a 50,000 HP minimum.  Speaking of which, I hear the only door you fit through now is your garage door. :laughing:


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## rlb0319 (Sep 1, 2009)

It is a natural gas compressor at a pipeline compression facility


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## MDShunk (Jan 7, 2007)

rlb0319 said:


> It is a natural gas compressor at a pipeline compression facility


Oh, then it's certainly a screw. It's not a Frick compressor, by chance, is it? I know Frick makes a lot of natural gas compressors.


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## RePhase277 (Feb 5, 2008)

Maybe it doesn't work this way for medium voltage stuff, I don't know. But can you "bump" it?


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## Boneshaker (Jul 31, 2009)

I agree with Shunk, if someone took this apart without any documentation he ed up. Leave your terminations as long as possible, (without causing a goat f---) check rotation and swap as needed. You probably wont be able to acomplish this in the VFD but may be able to back at the feeder compartment. Easier said than done I know, but you don't have a lot of options at this point.


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## wwilson174 (Apr 25, 2008)

rlb0319 said:


> We are in the process of changing out a VFD for a 13000Hp motor. All of the medium voltage power cable is also being replaced. does anyone have a suggestion as to verify rotation before we hook up the leads.


If you know the phase sequence of the power supply and you know the arrangement of the field coils in the stator ( available from the manufacturer) then you know in which direction the motor will rotate. This presumes that we are discussing an induction motor. BillW.


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## frenchelectrican (Mar 15, 2007)

What you should have Med / High voltage phase rotation tester and veirfiy the rotation sequince.

I know most POCO supply useally marked ABC or tape bands one of few common way { in Europe it will marked RST }

Veify it on the line supply to see if that line up and keep in your mind from time to time you may see phase rotating buss { it will show up once a while but not a whole alot unless you have hevey current drawage MV /HV set up.

Merci,Marc


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## micromind (Aug 11, 2007)

A few things come to mind here; 

1) The output of every VFD I've ever connected at any voltage has always been A-B-C. Regardless of the input rotation. If it turns wrong, does the VFD have a reverse feature? And can it be locked in reverse? Some of the medium voltage VFDs I've worked with can be programmed to lock out either forward or reverse.

2) If the motor can be un-coupled from the compressor (probably not easy at 13,000HP), and the shaft can be turned by hand, blast it with some 480. It likely will not turn by itself, but it'll be easier to turn by hand in one direction than the other. Then measure the 480 rotation. 

3) A lot of huge motors I've connected use differential protection for fault detection. If this is the case, and the rotation is changed by reversing leads, remember to change the CT secondary leads at the VFD output to match the opposite side of the motor. (Personal experience speaking here, I sure feel dumb sometimes!)

Rob


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## Zog (Apr 15, 2009)

Peter D said:


> What type of facility requires a 13,000 HP air compressor? Glass bottle plant?


I commisioned a 60,000HP motor once, big SOB. Used to suck all the air out of a building they tested jet engines in.


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## Zog (Apr 15, 2009)

frenchelectrican said:


> What you should have Med / High voltage phase rotation tester and veirfiy the rotation sequince.


Suprised it took so long for someone to state the obvious, get a phase rotation meter.


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## John Valdes (May 17, 2007)

Zog said:


> Suprised it took so long for someone to state the obvious, get a phase rotation meter.


Will not work with a VFD. Also the plant would have to have every panel, disco or lug block phased exactly the same way for the phase meter to be of any help. Personally I have never seen one help anyone. And have never seen a plant that had everything phased exact. Never. Some think they do, but they don't. Rotation on a 3 phase motor is 50/50. No better, no worse.

Set the ramp speed on the VFD to the highest setting possible. Most likely 999 seconds. Determine the correct rotation. Start the compressor. As soon as it starts to move shut it down. Now, you know if the leads must be reversed on the *load side* of the VFD. Or, you can change rotation in the parameters, provided you can change the interface to match. Meaning if the motor is going in the right direction, the control should not say its going in reverse.


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## drsparky (Nov 13, 2008)

John Valdes said:


> Will not work with a VFD. Also the plant would have to have every panel, disco or lug block phased exactly the same way for the phase meter to be of any help. Personally I have never seen one help anyone. And have never seen a plant that had everything phased exact. Never. Some think they do, but they don't. Rotation on a 3 phase motor is 50/50. No better, no worse.
> 
> Set the ramp speed on the VFD to the highest setting possible. Most likely 999 seconds. Determine the correct rotation. Start the compressor. As soon as it starts to move shut it down. Now, you know if the leads must be reversed on the *load side* of the VFD. Or, you can change rotation in the parameters, provided you can change the interface to match. Meaning if the motor is going in the right direction, the control should not say its going in reverse.


If you check rotation before you terminate a motor how do you get a 50/50? more like 100% chance of having it correct.:001_huh:


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## Lone Crapshooter (Nov 8, 2008)

Theway I check 2400 volt is with temporary insulation. I have 2 pieces of 15KV heatshrink that are shrunk on some PVC pipe . I make up 1 lead and eather heatshrink or tape it. Then I slip the temporary insulation over the other 2 leads and use a few quick raps of 88 to hold it on. Now this temporary insulation are about 12" long and our 2400 volt is unshielded.
Also the millwrights leave the coupelings broken when we bump the motors.


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## John Valdes (May 17, 2007)

drsparky said:


> If you check rotation before you terminate a motor how do you get a 50/50? more like 100% chance of having it correct.:001_huh:


You misunderstood my comment. In advance, you must know which way the motor should turn. Some people put an arrow on the machine so they know what direction it should turn. Determining the direction you want it to turn is the first thing you do.


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## drsparky (Nov 13, 2008)

John Valdes said:


> You misunderstood my comment. In advance, you must know which way the motor should turn. Some people put an arrow on the machine so they know what direction it should turn. Determining the direction you want it to turn is the first thing you do.


A rotation meter will show you the direction the motor will turn. It will also show the phase relationship of the motor leads. 100% chance of making the connections correct the first time.
Without a phase meter, yes it is 50%.


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## MDShunk (Jan 7, 2007)

drsparky said:


> Without a phase meter, yes it is 50%.


No, since my name is Marc, my chances increase to about 90% getting it wrong. :laughing:


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## micromind (Aug 11, 2007)

That's true for guys named Rob too!

Rob


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## InControl (Mar 20, 2007)

drsparky said:


> A rotation meter will show you the direction the motor will turn.


Yes




drsparky said:


> It will also show the phase relationship of the motor leads.


Yes




drsparky said:


> 100% chance of making the connections correct the first time.



Ahhhh, I see that you haven't met Mr. Murphy! He says otherwise. Mr. Murphy says that there is no such thing as 100%. I tend to agree. 

So you're saying that there's a 100% chance that 'YOUR' T1, T2, T3 on the motor will match up with the 'manufacturers' T1, T2, T3 on the VFD. 

Good luck with that line of thinking......


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## drsparky (Nov 13, 2008)

InControl said:


> Yes
> 
> 
> 
> ...


True, Murphys law can effect anything, a software error or a wiring error in the VFD can make for trouble. The power company can switch phases just before I power up a motor and the magnetic poles on the earth can swap. You can't plan for everything. My point is that with proper use of a rotation meter you can be 99% sure that the rotation is correct. This verses a 50/50 chance without use of a meter. Many terminations are not easy to swap. It can take an hour to change two of the three terminations.


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## John Valdes (May 17, 2007)

Dr., Whats a rotation meter? Is it the same as a phase meter? I have never used one if it's different. I can only go by past experience. When starting a 3 phase motor, you have 50/50 chance you will get it right the first time. I have seen people use phase meters with the same success. 50/50. Thats why I have never had any faith in the phase meter. Just never saw one work. I'm old school. If ya can't bump it, uncouple it. 

If this is a meter that you are familiar with, I am all ears and would like to know more about it. Maybe point me to one? A link? Thanks John


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## drsparky (Nov 13, 2008)

John Valdes said:


> Dr., Whats a rotation meter? Is it the same as a phase meter? I have never used one if it's different. I can only go by past experience. When starting a 3 phase motor, you have 50/50 chance you will get it right the first time. I have seen people use phase meters with the same success. 50/50. Thats why I have never had any faith in the phase meter. Just never saw one work. I'm old school. If ya can't bump it, uncouple it.
> 
> 
> If this is a meter that you are familiar with, I am all ears and would like to know more about it. Maybe point me to one? A link? Thanks John


Here is a few links, the first is hardware the second is a “how to” and theory.
http://www.mygreenlee.com/Products/...=showGreenleeProductTemplate&upc_number=07576
http://ecmweb.com/mag/electric_determining_motor_rotation/


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## electricalperson (Jan 11, 2008)

can you mark the motor leads ABC, trace each wire out and mark the leads feeding the drive ABC?


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## micromind (Aug 11, 2007)

As I know them, a rotation meter is a device that is connected to the leads of an unpowered motor, the shaft is turned by hand in the desired direction, and the meter will indicate whether CW (ABC) or CCW (CBA) phase rotation will cause it to turn the same way. 

A phase sequence meter is connected to a 3 phase power source, and it reads the phase sequence, or phase rotation. CW (ABC) or CCW (CBA). 

Quite a few years ago, I built a rotation meter from a couple of gate chips and some other stuff. It's powered by a 9V battery. It has 3 LEDS, and a pushbutton. One LEDs lights when the button is pushed and the battery is good. When the shaft is turned, one of the other LEDS will light. Either the one for ABC, or the one for CBA, not both. 

As far as I know, all phase sequence meters will show the same rotation. If the source is ABC, every meter will show it as ABC. 

I've used my rotation meter hundreds of times over the years, it's yet to be wrong. 

Here's how it works; first, the rotation of the source is determined. This is best done at the starter. If proper wire colors are maintained throughout the building, then the whole buildings rotation will be the same. Suppose it's ABC. 

Next, the rotation meter is connected to the motor leads. This is best done before the wire from the motor to the starter is connected. This meter works at VERY low voltage and current, it doesn't take much to make it not work. Once connected, the shaft is turned by hand. One of the lights will light. Suppose the CBA one does. This means that the source rotation and the desired motor rotation are different. I then know to reverse the rotation at the motor. Suppose the system is 480. I would connect brown to T3, orange to T2, and yellow to T1. 

The motor will then turn whatever direction I turned it by hand. 

Obviously, there's no point to doing this with a small motor that's turning a fan, and takes 10 seconds to reverse, but a big motor that's a major pain to change.....

Rob


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## drsparky (Nov 13, 2008)

Exactly, thank you for your explanation, I was getting tired of beating this dead horse.:thumbsup:


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## MDShunk (Jan 7, 2007)

micromind said:


> Here's how it works; first, the rotation of the source is determined. This is best done at the starter.


Pretty tricky if you're dealing with primary. Takes a whole other type of phaser.


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## InControl (Mar 20, 2007)

My point is..............ta da.....your ASSUMING that the phase rotation will match that of your VFD. The VFD does not care which way is up, as it does which way is clockwise.....The VFD does as its told, clockwise for one, counterclockwise for the other.


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## John Valdes (May 17, 2007)

Okay heres what I have learned from this discussion. A rotation meter will enable you to predict with 100% accuracy the direction a motor will turn before you power it up, but only when using across the line starting? If it's going to be connected to a VFD all bets are off? Did I get it or not?


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## 5volts (Jan 11, 2008)

With a VFD all bets are off!


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## drsparky (Nov 13, 2008)

I think most modern VFD output abc regardless of input. Knowing the motor leads and terminating them accordingly should give you the correct rotation. 
Of course I would still bump test every motor.


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## micromind (Aug 11, 2007)

I realize that this isn't absolute, but every VFD I've ever connected has been ABC on the output while in forward direction. 

That doesn't mean that there aren't any CBAs out there, if so, I've yet to see one. 

Rob


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## John Valdes (May 17, 2007)

electricalperson said:


> can you mark the motor leads ABC, trace each wire out and mark the leads feeding the drive ABC?


Sorry I missed your question. The answer is no. VFD's are not phase sensitive. :thumbsup:


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