How To Change Direction/Rotation

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JJWalecka

JJWalecka

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New England
Gmack,


Capacitor Starting Motor switch ether starting or running winding. Capacitor current leads voltage allows motor to have starting torque.

Justin J. Walecka
 
LarryFine

LarryFine

Master Electrician Electric Contractor Richmond VA
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Turn the motor around in its mount, and tap the shaft through to the other end with a hammer.



No?
 
dduffee260

dduffee260

Senior Member
Location
Texas
Gmack said:
What about a single phase 120/240/480 motor or high voltage 4160v poly phase etc.?
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Dunno about the 4160, I am gonna bet it is a 3 phase motor. The single phase motor you swap 5 & 8 or Red and Black. Just like a blower motor on a AC unit. This works for some I have seen, but look at the wiring diagram on any motor for instructions.
 
S

stew

Senior Member
Location
federal way,washington
so tell me larry what three phase motor have you ever seen that was not reversible? Funny I was owned an electic motor shop for 17 years in Seattle and I never saw the motor you describe. The only reason you would not reverse a 3 phase motor would be if the load such as some pumps, some compressors and a few other loads should not be reversed. All 3 phase motors will reverse if you swap 2 leads larry.
 
LarryFine

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
stew said:
so tell me larry what three phase motor have you ever seen that was not reversible? Funny I was owned an electic motor shop for 17 years in Seattle and I never saw the motor you describe. The only reason you would not reverse a 3 phase motor would be if the load such as some pumps, some compressors and a few other loads should not be reversed. All 3 phase motors will reverse if you swap 2 leads larry.
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Of course, any 3-phase motor will run the other way; how can it not? But aren't some motors, say totally-enclosed fan-cooled, required to run one direction for proper cooling?
 
iwire

iwire

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Location
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LarryFine said:
Of course, any 3-phase motor will run the other way; how can it not? But aren't some motors, say totally-enclosed fan-cooled, required to run one direction for proper cooling?
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I have never seen a TEFC motor that could not run either direction, the fans are centrifugal fans that 'blow' in the same direction regardless of the rotation direction.

Of course many motors are connected to equipment that will not like being spun backward.

Pumps with sprag clutches (a mechanical latch that keeps the motor from back spinning) come to mind.

Edit spelling
 
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dduffee260

dduffee260

Senior Member
Location
Texas
LarryFine said:
Not all 1ph motors are reversible, and even a few 3ph ones aren't.
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I would think any motor is reversible. Maybe not by changing leads, but pulling out the rotor and putting it in the other way. All the rotor is doing is following the leading flow. Is that right? Kind of like the little exhaust fans with the 0.9 hp motors.
 
charlie b

charlie b

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Causing a three phase motor to turn the other way is always possible by reversing any two phases. But that does not mean the motor will work well, or that it will even survive the change.

For example, if you change the direction of rotation, you also change the direction in which forces act on the motor bearings. A motor could be designed in such a way as to cause the forces to act on one bearing, and the bearings might be selected such that one, and only one, is capable of tolerating those forces. I do not know if any motors are actually built that way, but it is possible for certain specialized applications. But I suspect that some manufacturers have included instructions that warn the user not to operate the motor in the wrong direction.

My point is that you have to look beyond the wires, to discover whether it is acceptable to reverse the direction of rotation.
 
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