single phase motor reversing itself

[mikeatron]

evening all
ive got a single phase AC fan motor running normally however occasionally on start up it starts in reverse. i have 4 no fans, and this is happening to 2 occasionally. now these are in a fresh air chambers and i was starting to think that the airs blowing over the fans causing reverse rotation and then the capacitors havent got the umph to overcome this so they speed up backwards. is this possible?

all the fans are supplied via individual single phase inverters, all parameters are the same? ive never seen anything like it before

is there anything else that could cause this?

Cheers

 

[Aaron b]

My first thought was it was being blown in the wrong direction as it starts, I'm pretty sure it's happened to me before.

 

[westward10]

What is the span of the blades.

 

[Lucien Nunes]

What power rating are the motors? Do they run at or near normal full speed or are they deliberately being run slowly?
It is possible that the capacitors are failing; how old are they?

 

[apk2000]

evening all
ive got a single phase AC fan motor running normally however occasionally on start up it starts in reverse. i have 4 no fans, and this is happening to 2 occasionally. now these are in a fresh air chambers and i was starting to think that the airs blowing over the fans causing reverse rotation and then the capacitors havent got the umph to overcome this so they speed up backwards. is this possible?

all the fans are supplied via individual single phase inverters, all parameters are the same? ive never seen anything like it before

is there anything else that could cause this?

Cheers

Hi

The first idea is that there might be a conflict in the connections of the fans. However, since the issue been seen in a fresh air chambers it's possible that the reverse rotation may occur during blown air form the atmosphere.

Maybe there is a clutch that avoiding fans from rotating reversely .. if so i would suggest installing any means of devices to force the fans to rotate in one direction as long as these fans are only to blow air in one direction.

Neglecting that the fan's drivers aren't strong enough to overcome the external climate conditions, a mechanical means might be a good solution.