3 phase pump.... HELP!!!

[inchoate]

Hi guys,

I'm very confuse with the 3 Phase Motor and hope you can help. I do not understand why I can't obtain a consistent correct spinning of the motor even though I connect all the wiring correctly? For example, I have 10 motors and not all of them spin the correct direction even though they have the same wiring? Some spin clockwise while some spin counter-clockwise. I'm pretty sure they have all the same correct wiring as they are color coded.

Please advise.

 

[cbarn24050]

Hi, this is pretty much the norm. Allways check your motor spins the correct direction when installing. If its wrong just reverse any 2 leads, not the earth of course.

 

[inchoate]

Is there any explanation for causing the motor spin inconsistently? Why would some spin clockwise while some spin anti-clockwise when they are wired the same way?

I would appreciate it very much if someone could direct me to a website for explaination.

Thanks.

 

[jOmega]

In Europe, motors built to IEC standards have predetermined rotation for a specified phase rotation of the mains supply ..

In the NEMA does not incorporate such a standard for AC induction motors. (I believe it does for DC motors, however).

So, manufacturers are not obligated to mark the leads by any such convention. It's up to the assembler on the mfg. line to set the lead markings.

Thus, you have the opportunity for two apparently identical motors to have opposite rotation.

That's just the way it is.

Incidentally, NEMA MG-1, Part 31 for Inverter Motors, has a requirement for predetermined direction of rotation.
However, virtually no manufacturer complies with it and that is one reason why they are not able to state on the motor nameplate that their inverter motor is MG-1, Part 31 compliant.

 

[inchoate]

thanks jOmega.

I'm still wondering why the same manufacturer will produce the same motor that have different rotation. Wouldn't it be easy for them and the customers if they manufacture the same model motor that have same rotation so that customers do not need to confirm the rotation?

Thanks for any input.

 

[jOmega]

Couldn't have one manufacturer designate a rotation vs phase standard for his products while other manufactures could be different.

It's really not a big issue here ... we don't have a phase rotation standard for our power either.

It just isn't a big deal here. Been that way for over a century.... not likely to change any time soon.

We all bump our motors to check rotation at time of first application of power and swap two leads if its wrong.

To change to a standard, would require the power providers to have a standard rotation imposed upon them and then a rotation standard imposed on all motor manufacturers.

Who would pay for for correcting phase rotation at all users ??? certainly not the power companies..... they would pass this cost on to the users.... for sure.
And what about all of the motors now in use and in stock that don't conform to a standard. Who would pay to have them all changed to conform to a standard ? Are you willing to pay ?


So, not likely to be any changes or standard imposed.

 

[inchoate]

I see. Thanks for the clarification.

 

[mvcjr]

I agree with jOmega. European motors manufacturers indicate the supposed rotation of their motors for a given phase sequence.

With regards to your similar motors from the same manufacturer but having different directions of rotation, I guess that's where the human factor comes in. In the facility where I was previously connected we even had two similar motors from the same manufacturer having the same serial number!

God bless!

 

[jbartos]

Suggestion: If the motor has a different direction of rotation than required, it is always prudent to check if the motor is meant to be bidirectional. Some motors have an arrow. Therefore, such motor should follow a rotational direction of the arrow. Some loads are bidirectional, e.g. some compressors, floor shiner, etc. others are unidirectional, e.g. pumps.

 

[inchoate]

The motor I'm refering to are unidirectional. How does a phase sequence analyzer will help in getting a correct rotation? Also, is there a device on the market that can be used to ensure the motor spin in a correct direction?

 

[jbartos]

Suggestion to the previous posting: Unfortunately, motors come in such a variety that the devices for testing of motor rotation direction are not widely used. There are some testers that can show correct motor direction of rotation without actually energizing the motor. Visit

http://omnicontrols.com/lists/biddle2pm.html#gen1

etc. for more info

 

[jOmega]

inchoate Nov 7, 2003
[ul]The motor I'm refering to are unidirectional. How does a phase sequence analyzer will help in getting a correct rotation? Also, is there a device on the market that can be used to ensure the motor spin in a correct direction?[/ul] There are devices that will indicate the phase rotation of the ac supply.... but.... you asked if there's a device that will ensure the motor will spin in the correct direction.

Think about this: such a device would have to know how the motor was internally conntected and there is no device that can make that determination.

When motors are manufactured, it is not uncommon to bring the leads out and mark them once they are brought out without consideration to direction of rotation with respect to a given phase sequence.

The best way.... is to bump the motor, before coupling the shaft to the mechanical load.

 

[busbar]

There are testers that are intended for low-voltage motors and circuits. One is Hartman-Technica ‘Fastphaser’ PSMR-1, but seems to be out of production. Another is RK Electronics

http://www.rke.com/mrt.pdf

Both seem to be wide-voltage-range phase-sequence indicators that work from tens of millivolts to 600 volts without internally ranging or manual switching. When connected to motor terminals, they use residual magnetism in the motor stator to generate a small three-phase voltage when the connected motor’s shaft is rotated.

Neither of these devices have UL 61010A-1 {IEC 61010-1} installation-/overvoltage-category ratings, so must be used with significant care on an energized circuit.

 

[PUMPDESIGNER]

There are one way clutches used on some pumps where damage could occur from turning the wrong direction. Line shaft turbines with holo-shaft motors usually have these clutches built into the motor.

PUMPDESIGNER