# Amp draw



## macmikeman (Jan 23, 2007)

Check all the wiring connections.


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## John Valdes (May 17, 2007)

.8 amperes difference is not an issue. What was the voltage reading on that leg?


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## dronai (Apr 11, 2011)

John Valdes said:


> .8 amperes difference is not an issue. What was the voltage reading on that leg?


 
Off today John so I don't have my notes. But the nameplate was 2.7 fla at idle all phases at or under this number. 

with unloaded belt running (clutch engaged) about an amp higher than the fla with the one phases higher.


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## John Valdes (May 17, 2007)

If this is on a VFD you need not be to concerned. The VFD will monitor input and output power. If there is an issue on either, the VFD will fault.
If this is not on a VFD, then you need check every device in the motor circuit. Breaker, starter, motor connections (Terminal Block) or any place a connection is made. A bad set of contacts in the starter could be the issue for example or a faulty breaker.


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## wdestar (Jul 19, 2008)

Sorry to disagree, but a variance of 0.8 amps on a 2.7 amp full load seems rather significant... at least to me.

I agree with John - measure the voltage - phase to phase - and phase to neutral. It could be that this happens only occasionally, because I doubt the motor could withstand such a current inbalance for an extended period of time.

I would meg the motor. My guess it that it was subjected to single phasing a while ago and nobody noticed.


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## dronai (Apr 11, 2011)

Not a VFD on the motor. No CB either, everythings fused but several motors are taped off the same set of fuses. I'll have to check all connection points.


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## mrmike (Dec 10, 2010)

I thought the same as John until I saw your FLA's. You stated that several of the motors are coming off the same fuses ? That doesn't sound like a good set-up. Does each motor have an Overload someplace? That would trip over time if the f.l.a. was over that 2.7 amps.

I am thinking the same as wdestar. That motor is probably hurt . Unhook it at the motor and fuse or source and meg the motor & the wire feeding it seperatly......... The wire could be at fault and that one phase leaking to ground . I have also seen cables get wet & draw more amps like this.........


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## niteshift (Nov 21, 2007)

dronai said:


> Conveyor merge belt.
> 
> Doing a routine pm on a merge belt, I was amp testing the phases on a motor to see if the belt was too tight.
> 
> One of the phases was higher (by .8) This was a clutch brake motor. What would cause this ?


 
Age of motor could, is it hot to the touch, like you can't keep your fingrers on it. Could be the clutch/brake. Could be the gearbox causing the problem with the motor, is the gearbox hot to the touch? No/low oil in gearbox? Could be whatever is produced there is built up on mechanical stuff of the conveyor/s causing motor problem. 
At this point, doesn't sound important. 0.08a come on.


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## oliquir (Jan 13, 2011)

does the clutch connected to one phase of the motor wiring, if so you have your extra 0.8 amp


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## niteshift (Nov 21, 2007)

dronai said:


> Conveyor merge belt.
> 
> Doing a routine pm on a merge belt, I was amp testing the phases on a motor to see if the belt was too tight.
> 
> One of the phases was higher (by .8) This was a clutch brake motor. What would cause this ?


Post pics if possible.

Anything like these, swap out. Pull motor w/gearnox still attached, easier. 

WTH, I put a warehouse pic in there, no conveyors in there, yet.





















If its anything like this, troulbleshoot more first.


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## dronai (Apr 11, 2011)

mrmike said:


> I thought the same as John until I saw your FLA's. You stated that several of the motors are coming off the same fuses ? That doesn't sound like a good set-up. Does each motor have an Overload someplace? That would trip over time if the f.l.a. was over that 2.7 amps.
> 
> I am thinking the same as wdestar. That motor is probably hurt . Unhook it at the motor and fuse or source and meg the motor & the wire feeding it seperatly......... The wire could be at fault and that one phase leaking to ground . I have also seen cables get wet & draw more amps like this.........


*They all have overload protection after the fusing, and before the starters. Probably the motor dying. Those motors run continuosly 24/7 until needed, then then clutch engages.*



oliquir said:


> does the clutch connected to one phase of the motor wiring, if so you have your extra 0.8 amp


*No, it's a separate 90V DC source for the clutch/ brake*


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## nolabama (Oct 3, 2007)

Clutch adjustment? Brake motor out of adjustment, dragging brake?


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## micromind (Aug 11, 2007)

First, I'd check phase to phase voltages at the incoming lines of the control cabinet. Next, check voltages at the load side of the starter. These need to be very close to the same. if they're not, look for fall of potential across the components of the system. 

For example, check voltage from phase A of the incoming line to phase A at the load side of the starter, with the motor running. It should be very low, usually less than 1 volt, depending on how much stuff there is in the system. All 3 voltage drops should be close to each other. 

A small motor like that one is almost certainly wye wound, so high current on only one phase could easily be shorted turns in one of the windings. 

A megger test would be in order as here. First, since this is not an electronic control, megger one of the leads at the load side of the starter. There's no need to megger the other two, the readings will be the same because of the common connection of the motor windings.

If it's low, disconnect all 3 of the incoming wires to the motor. Megger all 3 at the starter this time, as they are all isolated. Megger one of the motor leads. 

This will tell you if the fault is inside the motor or in the wiring from the starter to the motor. 

0.8A difference on a 2.7A motor seems a bit high to me.


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## mrmike (Dec 10, 2010)

micromind said:


> .
> 
> A megger test would be in order as here. First, since this is not an electronic control, megger one of the leads at the load side of the starter. There's no need to megger the other two, the readings will be the same because of the common connection of the motor windings.
> 
> ...


 
I have meggared many motors in industry and worked in a shop of 20 electricians and I can tell you that this is not the way anyone ever meggared a motor. ONE Lead ??????? Dronrai, please do NOT do it this way, and you were probably already taught the proper way..

You MUST unhook all the leads at the starter, and meggar it there, Phase to Phase & Each Phase to ground. If any reading is bad, then unhook the motor leads and meggar between the motor leads 1 to 2- 2-3 & 1 to 3. Then meggar each lead to the ground of the motor.
If all ok then meggar the incoming feed the SAME way !!!


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## micromind (Aug 11, 2007)

mrmike said:


> I have meggared many motors in industry and worked in a shop of 20 electricians and I can tell you that this is not the way anyone ever meggared a motor. ONE Lead ??????? Dronrai, please do NOT do it this way, and you were probably already taught the proper way..
> 
> You MUST unhook all the leads at the starter, and meggar it there, Phase to Phase & Each Phase to ground. If any reading is bad, then unhook the motor leads and meggar between the motor leads 1 to 2- 2-3 & 1 to 3. Then meggar each lead to the ground of the motor.
> If all ok then meggar the incoming feed the SAME way !!!


If you megger a motor from 1-2, 2-3 & 1-3, and the motor leads are made up, every test will be a fail. If you unsplice every lead, then you can megger individual windings, but you need to know how the motor is wound. 

If you're meggering to ground, one lead of a motor with the leads spliced will do the exact same thing as meggering the other leads. 

Why would you unhook all the leads at the starter? Certainly, if it were an electronic type you'd need to, but not a simple mechanical one. If you leave the leads connected, you'll include the load side of the starter in the test. 

If you unhook all the leads at the starter and megger phase to phase, it'll fail every time. You're meggering the low resistance of the windings.


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## mrmike (Dec 10, 2010)

micromind said:


> If you megger a motor from 1-2, 2-3 & 1-3, and the motor leads are made up, every test will be a fail. If you unsplice every lead, then you can megger individual windings, but you need to know how the motor is wound.
> 
> If you're meggering to ground, one lead of a motor with the leads spliced will do the exact same thing as meggering the other leads.
> 
> ...


 
First of all, I said to unhook the leads at the starter/contactor & I meant at the bottom of it that going to the motor. This is common sense as the starters contacts are open ! 

This is the most logical & easiest place to start to find out the integrity of the motor and cable going to it. Then, if you find something suspect, you have to go to the motor-unhook that and check it & the cable going back to the starter. You MUST unhook all 3 and meggar them as I stated. Phase to Phase- Phase to Ground- no other way!

Yes, you are meggaring the resistance of the windings. You are measuring for continuity to see if you have an open (single phase) between them. And you are measuring each phase to ground looking for infinity. YOU DO NOT JUST MEGGAR ONE LEAD.


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## Jlarson (Jun 28, 2009)

mrmike said:


> I have meggared many motors in industry and worked in a shop of 20 electricians and I can tell you that this is not the way anyone ever meggared a motor.


Cool story :laughing:


I'm like micro, try to avoid disconnecting more then necessary. 

Dronai work smart, move downstream, FOP test at the starter, meg the field wiring and motor, break them apart and meg, then if you have to check the motor on its own.


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## mrmike (Dec 10, 2010)

Jlarson said:


> Cool story :laughing:
> 
> 
> I'm like micro, try to avoid disconnecting more then necessary.
> ...


 

 What did I say ????? What can't you understand?
If your like Micro you are not working smart !!! Study my posts & think about it some. Micro's way is the highway where I worked !:laughing: 

No story:laughing: just 25 years in the industry with meggaring hundreds of motors or more. Probably meggared more in one day than you have in a lifetime...................


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## micromind (Aug 11, 2007)

mrmike said:


> Yes, you are meggaring the resistance of the windings. You are measuring for continuity to see if you have an open (single phase) between them. And you are measuring each phase to ground looking for infinity. YOU DO NOT JUST MEGGAR ONE LEAD.


Anyone who uses a megger to check for continuity doesn't understand the purpose of a megger. 

When meggering a motor, it's a LOT quicker to megger one lead of a motor that's made up than it is to unsplice each lead and megger each coil separately. The vast majority of the time, any problem with a motor will show up if it's meggered from one lead to ground while it's still made up. 

You can either work smart and therefore fast, or you can waste a bunch of time by blindly following some sort of procedure and not skipping unnecessary steps. 

But, in order to skip the unnecessary steps, you need a working knowledge of your test instruments as well as the device under test.


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## Jlarson (Jun 28, 2009)

mrmike said:


> Study my posts & think about it some.


Don't need to, I can pick out wastes of time quickly. 



mrmike said:


> Probably meggared more in one day than you have in a lifetime...................


:no:




micromind said:


> Anyone who uses a megger to check for continuity doesn't understand the purpose of a megger.


I use mine to check continuity... but mine is one of them fancy new digital deals with an ohms range too :laughing:


Going along with disconnecting as little as possible, when it comes time to meg the field wiring and the motor separately if you have a disco right at the motor open it and meg from there.


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## mrmike (Dec 10, 2010)

It is apparent that you 2 have not worked out in a daily "work" enviroment where it was dependent on you and other electricians to keep a plant running. The term continuity isn't meant to be ohms but to define between the phases of the field wiring. 
When a PDC trips before a breaker on an MCC stack & You to have to meg every motor on that stack to find out which one tripped it- you had better not do it your way- 
END OF STORY !!:whistling2::whistling2:


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## Big John (May 23, 2010)

micromind said:


> ...When meggering a motor, it's a LOT quicker to megger one lead of a motor that's made up than it is to unsplice each lead and megger each coil separately. The vast majority of the time, any problem with a motor will show up if it's meggered from one lead to ground while it's still made up....


 Absolutely. If you have a stator ground fault, as long as the motor is connected, you're gonna pick it up by connecting between any one lead and ground.

No need to bother with disconnecting a bunch of stuff.

-John


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## dronai (Apr 11, 2011)

The sad thing about my job is, they wont let me spend any time fixing things, unless it's effecting the whole system. We have to toss motors if the bearings are shot ! More important is that the system keeps running, and doesn't hold up anything, that could cost them thousands in fines. Nice to have a big budget like that. 

On my shift the Pm's are too locate potential problems, and let the graveyard shift do the replacements. (They have 3 hours that they can take the system down) So I am for the emergencies only, on the swing shift. 

I love the automation, but the communting, and night hours are killing me. My contracting business is really getting busy now. My brother is not keeping up with the pace. There's no point in letting a 25 year old established business go for a job that they can fire you some day. So unfortunately my days are numbered.


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## mrmike (Dec 10, 2010)

Big John said:


> Absolutely. If you have a stator ground fault, as long as the motor is connected, you're gonna pick it up by connecting between any one lead and ground.
> 
> No need to bother with disconnecting a bunch of stuff.
> 
> -John


 I stated You DISCONNECT THE MOTOR after you find something. You start troubleshooting or a PM check at the starter or overload block where the wires are going out to the motor. We meggared all 3 as I stated. THIS was the procedure in our company. 

Going to one lead to ground is not going to find An open unless it just happened to be on that lead. That is why the meggaring from phase to phase 1-2 2-3 & 1-3. There can be a burned open lead in the motor connection box or wiring,etc.


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## Jlarson (Jun 28, 2009)

mrmike said:


> keep a plant running.


You're right... I'm depended on to keep more like 20 different plants and 100's of small sites running. :lol:


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## mrmike (Dec 10, 2010)

Jlarson said:


> You're right... I'm depended on to keep more like 20 different plants and 100's of small sites running. :lol:


 :notworthy:Wow, Where do you find the time to be on here??? You the Man !!!!


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## niteshift (Nov 21, 2007)

dronai said:


> The sad thing about my job is, they wont let me spend any time fixing things, unless it's effecting the whole system. We have to toss motors if the bearings are shot ! More important is that the system keeps running, and doesn't hold up anything, that could cost them thousands in fines. Nice to have a big budget like that.
> 
> On my shift the Pm's are too locate potential problems, and let the graveyard shift do the replacements. (They have 3 hours that they can take the system down) So I am for the emergencies only, on the swing shift.
> 
> I love the automation, but the communting, and night hours are killing me. My contracting business is really getting busy now. My brother is not keeping up with the pace. There's no point in letting a 25 year old established business go for a job that they can fire you some day. So unfortunately my days are numbered.


I agree, little differant situation for me. We only run at night, so we have spares to cover it when we pull or replace electrical/pc/mechanical to get thru a run. Day shift will handle rest of repair(s) if needed. 

Alot of stuff here gets chucked too. You know all the repair replacement is fiqured into the budgets. Companies always have a way to get money to fix whatever makes thier widgets, or go out of business, so we have a real good chance of not losing our jobs. 
Long as we keep them widget makers running life is good.

This is my only job now. I understand about your buisiness suffering due to being there at night. 
I had this job before I started my ec business. I kept both, kept working that way, did it for 10 yrs.
Alot more suffers then your buisness when working 2 jobs away from home.
I am the only electrcian/machinist along with a tech guy here at night. We help each other out.:thumbup: Something "breaks", in production, unless it is redundant, it gets fixed or we don't run. Did I say everything else in the building we have to cover at night to.
We don't get fined though. Still is a real bad thing, not to run.

Day shift has same situation minus run.
Commute I don't mind too much as all the rush hr traffic is goin opposite way.
No guarantee at any job. 
Night work. Day work. You can do either.


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## Frank Mc (Nov 7, 2010)

mrmike said:


> I stated You DISCONNECT THE MOTOR after you find something. You start troubleshooting or a PM check at the starter or overload block where the wires are going out to the motor. We meggared all 3 as I stated. THIS was the procedure in our company.
> 
> Going to one lead to ground is not going to find An open unless it just happened to be on that lead. That is why the meggaring from phase to phase 1-2 2-3 & 1-3. There can be a burned open lead in the motor connection box or wiring,etc.


Mike

If there,s an open leg then tong (amp) testing will show this? ???....Meggar testing one leg to ground as mentioned will show up a ground on any of the other two....I must be missing something here...

Frank


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## mrmike (Dec 10, 2010)

Frank Mc said:


> Mike
> 
> If there,s an open leg then tong (amp) testing will show this? ???....Meggar testing one leg to ground as mentioned will show up a ground on any of the other two....I must be missing something here...
> 
> Frank


Frank, Yes, you are missing it too. For example, your motor overloads or breaker tripped. How can you amp test that? Meggaring phase to phase like I stated will show an open . 

If you happen to meggar that lead to ground, that is sitting there open, looking for a ground,what will it show?

Another example-the incoming feed wire leg burns open in the peckerhead and ground itself to the motor. the motor lead itself is just dangling there open. You meggared another leg at the starter. What will you show?

I've seen these scenario's many times, thus the reasoning for meggaring all 3 leads to ground & phase to phase when troubleshooting............
Of course most times you would use your Multimeter on ohms for checking for these things, before you get out the meggar, but you would check them the exact same way !!


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## dronai (Apr 11, 2011)

I am confused now ! Phase to ground megger testing will show a breakdown in insulation. Phases to Phase testing with a DMM set on continuity, will show continuity unless one phase is open. But meggering phase to phase will fail everytime with the motor leads connected, because they have a common connection point in the motor right ?


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## Big John (May 23, 2010)

dronai said:


> ...But meggering phase to phase will fail everytime with the motor leads connected, because they have a common connection point in the motor right ?


 Correct. If you think you've got a phase-to-phase short, or you're trying to nail down exactly which winding has a ground-fault, then you break them open and start re-testing.

-John


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## mrmike (Dec 10, 2010)

dronai said:


> I am confused now ! Phase to ground megger testing will show a breakdown in insulation. Phases to Phase testing with a DMM set on continuity, will show continuity unless one phase is open. But meggering phase to phase will fail everytime with the motor leads connected, because they have a common connection point in the motor right ?


 

Sorry if it confusing to you. Meggaring Phase to Phase from the starter will NOT fail with the motor leads hooked up. If one connection is open You will get infinity, informing you that there is an open between two leads.. No Reading thru the windings.
That common connection point is broken...................
I know that we are looking for the integrety of the insulation of the windings and that is why the meggar test but it also will show these things for troubleshooting.......

With proper connection thru the wire feed & windings you should get 0 when testing phase to phase.... 

Phase to ground meggaring will also show a wet motor. Working in a Paper plant we had many instances of this. We actually took end bells off of big wet motors, and if we could put heat & air to them, until the meggar reading was acceptable to start & use them..................


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