caps in motor ckt.

[221122]

capicitors in a motor ckt, have a cooling fan (2 ea.) 460 volt 1 phase 1.6 fla......
I have a problem when one fan comes on the other comes on comes on line and wants to run in the opposite direction ( air flow starts it in that direction). I have 10 micro farad caps (run) in the ckt.
when the contactor is disconnected ( fan #1or fan#2) they work like they are supposed to.
my question is;
1.how can I boost the start in the direction it is supposed to be with out damage to the motor?
2.can I use a cap to start it although it is a run capicitor ckt?
3.how to size caps for this application?
4. when caps are series and paralelled what happens to voltage and amperage?
thanks, ps this is a great place to get info and idea's !!!

 

[marissa2]

Re: caps in motor ckt.

Can you block the air flow between the two fans so that it doesn't effect the second fan. Also what are these fans on.
Lou

 

[stew]

Re: caps in motor ckt.

Marrissa a cap run motor is actuaslly a shaded pole design motor and cannot be retrofitted with a start capacitor. Thier is only one winding in this design motor and that winding is not able to produce the starting torque that a start winding in a capacitor start motor can. I think you are faced with canging the mechanical design of this setup to cure your problem.Even if you were to use a cap start motor the slugging action to get the inertia of the fan stopped and then reversed would very probably damage the start winding as It would be subjected to start current for way longer than desigined.

 

[steve66]

Re: caps in motor ckt.

Is there a separate way for air to get throught the enclosures besides the other fan? If not maybe you need to provide a larger vent. Otherwise, maybe you can start the fans at the same time. Or use a different fan.

Steve

 

[marissa2]

Re: caps in motor ckt.

Stew
I never said anything about a capacitor. But if this a A.C. condenser unit that has a dirty coil, I have seen the second fan spin in reverse when the first fan starts because it will pull air from anyplace it can.
Lou

 

[221122]

Re: caps in motor ckt.

thanks gang, all the advice is good and I will run with it!!!
aloha