Trouble with a 3 phase motor

[Darkwood]

Motor speed is a major issue with fans. Centrifugal forces can destroy a fan. Seeing a fan launched out of the top of a building isn’t something I want so see again.

He said that the second one burnt out in a day but see your point the C - forces could have destroyed bearings etc jamming motor and burning it out, the thought hadn't crossed my mind but think ive been spending too long on closed loop inverter controlled systems - got my blinkers on i think, but either way OP is lacking info and the guys he's had out to fix the motor dont seem to know what they are doing so a dead end for helping him.

 

[Marvo]

This thread is beginning to worry me. There's some things that make no sense to me whatsoever. For example how do you rewind a 4-pole motor and make it into a 2-pole motor or vice versa? I didn't know this was even possible.

There's a balancing act you've got to play assuming this is an axial fan. On one side of the equation you have the motor shaft power, on the other side you have the speed of rotation and the blade angle. Where the right balance lies depends on many things such as the power characteristics of the blade set and the static pressure of the system and so on.

Without many accurate details there's no way we can assist you any further.

 

[Engineer54]

Quite agree Marvo, there's a lot more to specifying a motor, than is at first apparant. It takes a lot of experience and know how, and very little from what you can gain out of books.

 

[Knobhead]

I’ve said my piece, now I’m washing my hands of it.