Is there a standard (for motor manufactures) so we know motor rotation?

[wireguy8169]

I was reading another post and did not want to start a thread with in a thread so I am posting fresh. We are currently installing four 50hp pumps in our waste water facility. They are coming in completlely assembled and Laser aligned. Anyhow, two of the guys finished the first and were ready to test it and a question arose, regarding rotation. Anyhow to make a long story short, is there a standard for motor manufactures, when they build a motor if you hook up the lines (lets just say) 1-A, 2-B, 3-C (as verfied by a phase sequencer) that the motor will have a certain rotation? I have in my experience marked the phases (as they were removed from a motor) and after installing the new motor the same way it still had the wrong rotation (I am sure most of us have). Well, if there is not a standard there should be. I do know that the company that rebuilds our motors especially the larger ones when they test it will give us the rotation and hook up.

 

[jim dungar]

Don't forget, there is no standard on how facility systems are 'phase rotated' either. Once, I was selling rotation meters to a conveyor manufacturer. During our discussions it came out that they rewired machines as they moved through the facility, because no one had ever taken the time to standardize the wiring in the test stations.

 

[ATSman]

I was reading another post and did not want to start a thread with in a thread so I am posting fresh. We are currently installing four 50hp pumps in our waste water facility. They are coming in completlely assembled and Laser aligned. Anyhow, two of the guys finished the first and were ready to test it and a question arose, regarding rotation. Anyhow to make a long story short, is there a standard for motor manufactures, when they build a motor if you hook up the lines (lets just say) 1-A, 2-B, 3-C (as verfied by a phase sequencer) that the motor will have a certain rotation? I have in my experience marked the phases (as they were removed from a motor) and after installing the new motor the same way it still had the wrong rotation (I am sure most of us have). Well, if there is not a standard there should be. I do know that the company that rebuilds our motors especially the larger ones when they test it will give us the rotation and hook up.

Not sure this helps but I know that the industry standard for most protective relays and power monitoring meters is A-B-C CLOCKWISE. The utility for most of CA is PG&E and I would estimate that 90% of their LV services are provided with C-B-A COUNTER-CLOCKWISE rotation.This is a constant source of confusion and extra work in changing cables for contractors who tend to wire everything in A-B-C rotation. Strange
I am curious to know what rotation other utilities provide in other states ? Anyone ??

 

[iwire]

In my experience the utility does not know or care which phase is really A or B or C.

We were working with the utility while they were cutting over to a new double fed small substation and it kept shutting it self down when they tried to energize it. It turned out they had one feeder landed reverse phase.

 

[ATSman]

In my experience the utility does not know or care which phase is really A or B or C.

We were working with the utility while they were cutting over to a new double fed small substation and it kept shutting it self down when they tried to energize it. It turned out they had one feeder landed reverse phase.

iwire,
I assume you are referring to new installations. If the utility co. is replacing one of their transformers at a facility they better well know and care that they match the rotation of the load, otherwise, if the main switchboard has no 47 relay to prevent the main from closing, then plenty of load damage could occure for the customer.

 

[iwire]

iwire,
I assume you are referring to new installations. If the utility co. is replacing one of their transformers at a facility they better well know and care that they match the rotation of the load, otherwise, if the main switchboard has no 47 relay to prevent the main from closing, then plenty of load damage could occure for the customer.

Anytime we have worked with the utility it has been up to us to ensure the rotation was correct. I have had to have them swap elbows on a pad mount because they had reversed the rotation on us.

 

[Smart $]

... Anyhow to make a long story short, is there a standard for motor manufactures, when they build a motor if you hook up the lines (lets just say) 1-A, 2-B, 3-C (as verfied by a phase sequencer) that the motor will have a certain rotation? ...

Standard is CW when looking at the drive-shaft end... or CCW looking at the other end. If you wire as such, with verified phasing, the probability of correct rotation is greater than 50%

 

[Hv&Lv]

Not sure this helps but I know that the industry standard for most protective relays and power monitoring meters is A-B-C CLOCKWISE. The utility for most of CA is PG&E and I would estimate that 90% of their LV services are provided with C-B-A COUNTER-CLOCKWISE rotation.This is a constant source of confusion and extra work in changing cables for contractors who tend to wire everything in A-B-C rotation. Strange
I am curious to know what rotation other utilities provide in other states ? Anyone ??

I don't know if any utility has a standard rotation, that is one reason we carry rotation meters. When a bank is built or padmount is originally set, rotation is the electricians responsibility. After that, it is the utilities responsibility. Now, before someone lambastes me for this statement, think about it. What happens when a utility has to change out a bank or a padmount for maintanience. We take rotation and make sure it is right before we leave.

It would be hard to set a standard rotation since rotation starts at the source. (transmission) any roll in the transmission line can change rotation, and once it gets to the substation routing the jumpers can change rotation again. Still again, rotation can be switched back and forth throughout distribution by having incorrect rolls in three corners and jumpers at buckarm angles. Normally we try to keep a substation either clockwise or counterclockwise throughout thecircuits coming off the substations. Consequently, three of our biggest stations are counterclockwise, so the 17 circuits coming from it are counterclockwise.

 

[hurk27]

Not sure if it is because we are in a heavy industrialized area but our utility adheres to a CW rotation and phase marks all their conductors R,W,B, with a grounded delta service they land 1-B, 2-R, 3-W in their meters, and we land it as 1-R, 2-W, 3-B at our mains, "W" being the grounded "B" phase, both landings are in a CW rotation.

Of course we use dirrerant colors then they do at our mains.

 

[Hv&Lv]

Anytime we have worked with the utility it has been up to us to ensure the rotation was correct. I have had to have them swap elbows on a pad mount because they had reversed the rotation on us.

I would be curious to know what type of work they were doing to reverse rotation where the need to swap elbows came into play. Were they changing out a pole or switching circuits in a vault, or what? May even be that the ones doing a simple padmount change didn't pay attention to where the elbows were landed in the first place and switched them up when reenergizing the XF.

You are right that we generally don't care about A-B-C, B-C-A, C-A-B, or even any of the reverse rotation configurations unless we are parallelling or two way feeding something. Then we get into 25kV phase bucking(or 15 depending on utility), which sounds like what happened to the small sub you mentioned. Doing this in air is a good reason for arc protection...

 

[ATSman]

I agree with most of the comments made here but the simple point I am trying to make is once the phase rotation is measured at the service entrance by the installer when the building is built and all the loads (motors, UPS, gensets, etc.) are wired then it is the responsibility of the utility co to maintain that rotation, i.e. when changing out their defective transformer to the building. Otherwise the customer would have to rewire all his 3 phase loads, which is never the case.
Case in point: I was called out by the Telco Co after the utility co changed out a pole mounted xfmr. They had to transfer their load to their generator for 3 days while the work was being done. When the work was done and it was time for Telco to switch their loads off generator, the breakers never transferred back to utility. The transfer scheme had a 47 relay (phase rotation/ loss of phase protection) which was not picked up preventing the breakers from transferring to utility.The utility rolled (changed phase rotation) the phases and had to come back and rewire the transformer secondary to match the building before the transfer scheme would transfer the load to utility power.

 

[rbalex]

Assuming a phase sequence of 1-2-3, A-B-C, R-S-T,etc., per NEMA MG-1:

2.23 DIRECTION OF ROTATION OF PHASORS Phasor diagrams shall be shown so that advance in phase of one phasor with respect to another is in the counter-clockwise direction.See Figure 2-14 in which phasor 1 is 120 degrees in advance of phasor 2 and the phase sequence is 1,2,3.

2.24 DIRECTION OF ROTATION
The standard direction of rotation for alternating-current generators is clockwise when facing the end of the machine opposite the drive end.
The direction of rotation of a generator mounted as apart of an engine-generator set is usually counterclockwise when facing the end opposite the drive end.
The standard direction of rotation for all alternating-current single-phase motors, all synchronous motors, and all universal motors shall be counterclockwise when facing the end of the machine opposite the drive end.

NOTE: While it doesn?t matter 9 times out of 10, when discussing the issue, phases don?t rotate, they oscillate. Motors, magnetic fields and phasors rotate. In that tenth time,when it is important, it is better to state "phase sequence" to a motor rather than "phase rotation.?

For some reason I can't seem to get Figure 2-14 to copy properly. It is essentially an inverted "Y" with the vertical upper leg labeled "1," the lower right leg labeled "2," and the lower left leg labeled "3."

 

[texie]

I agree with most of the comments made here but the simple point I am trying to make is once the phase rotation is measured at the service entrance by the installer when the building is built and all the loads (motors, UPS, gensets, etc.) are wired then it is the responsibility of the utility co to maintain that rotation, i.e. when changing out their defective transformer to the building. Otherwise the customer would have to rewire all his 3 phase loads, which is never the case.
Case in point: I was called out by the Telco Co after the utility co changed out a pole mounted xfmr. They had to transfer their load to their generator for 3 days while the work was being done. When the work was done and it was time for Telco to switch their loads off generator, the breakers never transferred back to utility. The transfer scheme had a 47 relay (phase rotation/ loss of phase protection) which was not picked up preventing the breakers from transferring to utility.The utility rolled (changed phase rotation) the phases and had to come back and rewire the transformer secondary to match the building before the transfer scheme would transfer the load to utility power.

I agree that the utility has a responsiblity to maintain the same rotation after a transformer (or other equipment) failure. I've had some utility people in the past so concerned that they weren't really sure what the rotation was before the failure that they won't renergize the service unless the customers own electrician confirms proper rotation so they are not held liable.

 

[Stevareno]

The utility people around here usually put rotation stickers on their equipment, presumably to prevent impacting customers when they have to change out the equipment.

Even if motor manufacturers have a standard in how they wire the motors rotation wise, there is no way to predict before hand how the premisis utility is wired so it is up to the electrician to verify that rotation is correct any time they hook up a motor.

 

[Smart $]

...For some reason I can't seem to get Figure 2-14 to copy properly. It is essentially an inverted "Y" with the vertical upper leg labeled "1," the lower right leg labeled "2," and the lower left leg labeled "3."

 

[kingpb]

The order in which the phases reach their positive maximum when rotated in the CCW is the phase sequence.

If you don't specify anything different, you will probably get A, B, C or 1, 2, 3 or R, S, T. Just look at Smart $ avatar, and previous post, it is a good example.

There can be variations at the service point, which by all means is the utilities responsibility to maintain. This could be due to either rolling the phases on distribution lines (planned and accidental), rolled phases at transformers (planned and accidental) or just the way buy their generators and operate their system, i.e. A, C, B. Either way once they are established at the service entrance to a facility the utility must maintain, or serious damage to a plant can occur. Within the facility boundary, it is the electrician's responsibility to maintain and check.

 

[kwired]

Now that we have discussed the utility lets return to the OP's question.

Is there a standard for motors? I know very well ABC does not matter the actual sequence does. If you input a specific phase sequence to any motor will you get same rotation every time? Smart said more than 50% of the time you will. I'm guessing if you stick with one brand of motor you likely will, but not sure if you will across all manufacturers - at least ones following NEMA standards. If there is a standard is it also normally followed by motor rebuilding shops?

 

[rbalex]

View attachment 6097

Thanks, I needed that

 

[wireguy8169]

Clarification

Clarification

I see some of the post (and thanks for them all) misunderstood what I was asking, probably more true is I was not clear enough in my post so I will try again.

What I was wondering is if motor manufactures when they build motors build them so that (just for instance) if you hook what you have verified as A-B-C phases by rotation meter or other means to the motors 1-2-3 if they have a standard that its rotation is clockwise. I know in the past I have or have been part of a motor change out where we have marked the leads, wired it up, bumped it and the rotation was incorrect.

As I stated in my OP when we send out our motors to be rewound we have requested that when they test it they let us know mainly on our larger pump motors.

My question is more out of curiosity than anything else but I guess its hard to have a standard when most of the motors are made else where.

Thanks for all the replies.

 

[wireguy8169]

Now that we have discussed the utility lets return to the OP's question.

Is there a standard for motors? I know very well ABC does not matter the actual sequence does. If you input a specific phase sequence to any motor will you get same rotation every time? Smart said more than 50% of the time you will. I'm guessing if you stick with one brand of motor you likely will, but not sure if you will across all manufacturers - at least ones following NEMA standards. If there is a standard is it also normally followed by motor rebuilding shops?

Thanks K