extract fan motor issues

thommo · Jul 24, 2012

Hi All,
forgive me if this has been covered and if this post is in wrong section but the general forum wouldn't open up for me.
Now the problem i got is, i went to a job to wire up an extract fan in a pub after they bought a new gas oven the gas is controlled by a valve, emergency stop and pressure sensor all work fine.
The fan motor i believe has two windings with the second set connected to a capacitor and the fan is controlled by an efsc-06 controller, this is where i need help, up to about 80% the fan works ok but the last 20% the fan starts rotating the opposite way. It is single phase.
I have checked the manufacturers wiring diagrams countless times and what i have done is cIt us orrect.
It is starting to give myself and the client a massive headache, so any thoughts or suggestions would be appreciated.
thanks

stef · Jul 24, 2012

Hi thommo, this could be down to the capacitor. It's purpose is to simulate a second phase. I assume that it is rated for 50hz. So it is possible that the capacity of it is wrong due to a failing component. If youmhave a multimeter with capacity range it might be worth checking.

Knobhead · Jul 24, 2012

Give the manufacturer a call

stef · Jul 24, 2012

The pther option is of course a faulty controller.

thommo · Jul 24, 2012

Thanks for the replys.
I have replaced the controller as that was my first thought, i have tried a different capacitor allbeit a fair bit bigger than the original (just for checking purposes) but neither has made a difference,
I would like to think that it isn't the fan motor itself but that's all that is left apart from another capacitor that is the correct size,

really starting to do my head in.

Knobhead · Jul 24, 2012

The bit I can’t get my head around is the motor accelerating to 80% and then reversing. It’s a wonder the motor and controller hasn’t blown up!
Here’s a suggestion to try, reverse the start winding.

View attachment 13758

thommo · Jul 24, 2012

When the fan has got up to speed at 80% and turned it that extra 20% the fan slows first, with the fan at standstill at i turn the controller from 0 to full it starts rotating the correct way and then stops and starts rotating the other way,
btw thanks for the diagrams

Marvo · Jul 24, 2012

What is the make and model number of the motor preferably or at least the fan unit. In 25 years of working I've seen some pretty weird things but I ain't never seen a motor get to 80% of full speed and then go into reverse. I'll make predictions that the capacitor isn't going to survive long and you'll have silver confetti everywhere when it goes.

Has the motor got a centrifugal switch in the back of it ie is it split phase Capacitor Start/Induction Run (CS) or Capacitor Start/ Capacitor Run CSCR (CSR). Does it have different wiring options for 110/220v (split run winding)?

**EDIT** What does the motor do if you remove the speed controller and wire it directly on line? What is the run current and is it less than the max allowable run current stated on the motor plate?

thommo · Jul 24, 2012

Ok fan model no:aer 400-4a,
made by wolter (german company)
I haven't seen it go into reverse from 80% but it has slowed down but from standstill after the initial startup when turning the dial up full the fan slows,stops and goes into reverse.
I haven't looked at the motor itself as it was already installed when i first got there i just wired the controller up, i believe the capacitor kicks in the second winding on the fan motor.
no different wiring options.
and i haven't bypassed the speed controller.
Sorry if it is vague

Marvo · Jul 24, 2012

Well it says in the brochure that they're speed controllable by either transformer (voltage) or electronic (phase angle/PWM).I would suggest you remove the speed control and go back to basics. Get the fan running DOL and check the running current is within spec. Also check the current through the run winding and through the capacitor and make sure nothing looks hinkey. If the fan is running in reverse as you say it is I would suspect either incorrect wiring or an open circuit capacitor or winding.