3 phase pump.... HELP!!!
3 phase pump.... HELP!!!
(OP)
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.
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.





RE: 3 phase pump.... HELP!!!
RE: 3 phase pump.... HELP!!!
I would appreciate it very much if someone could direct me to a website for explaination.
Thanks.
RE: 3 phase pump.... HELP!!!
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.
RE: 3 phase pump.... HELP!!!
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.
RE: 3 phase pump.... HELP!!!
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.
RE: 3 phase pump.... HELP!!!
RE: 3 phase pump.... HELP!!!
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!
RE: 3 phase pump.... HELP!!!
RE: 3 phase pump.... HELP!!!
RE: 3 phase pump.... HELP!!!
http://omnicontrols.com/lists/biddle2pm.html#gen1
etc. for more info
RE: 3 phase pump.... HELP!!!
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?
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.
RE: 3 phase pump.... HELP!!!
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 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.
RE: 3 phase pump.... HELP!!!
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