A client of mine has run 2 roller shutters off a single switch, this is against manufacturers reccomendations, I wanted to find out just exactly what happens when you do that. So i wanted to know what kind of motors they are, ive since found out.....5 mins ago they are
Split phase capacitor run
They aren't operating at all now and they are still in situ, I figured the start winding may have burned out they only consume a few amps (possibly 10 @ start up). They were connected direct to an incorrect mcb 32A ...whoops any thoughts
As far as I know there is nothing intrinsically wrong with starting two motors from one switch. Clearly a 32 A circuit breaker will not protect either one. You can Ohm the motor windings to see if a motor winding has opened up. Also if something like a lamp switch was used to turn on the motors it could have opened up (lots of inductive arcing from motors).
I clearly need to clarify what I meant in my previous post. I don't know of any electrical reason that switching two motors on ond off from a single switch would cause the motors to fail. Not causing smoke and fire, protecting the motors and adhering to code is a completely different story.
Those motors CANNOT be run off the same switch! They are a three wire design (common, forward & reverse) that OPENS the Forward or Reverse wire in order to change direction. Paralleling the motors allows current to cross from one motor to the other. This will then burn the motors up! These motors have to have either the forward or reverse lead open!
A bit more...
You apply power to TWO leads ONLY to make it go one direction. It is a PSC design that uses a capacitor between the forward and reverse leads (internally). So, putting motors in parrallel would mean there is no longer an open on the unused direction!
Thanks people this is helpful, judging from my customers feedback both these motors initially started to work simultaneously, then stopped. I think my understanding of these motors needs clarifying. Is the problem increased because one of these motors is driving right handed and the other left handed, or doesn't it matter
We normally use a group controller for this kind of control. How would this device prevent that from happening.
My customer didnt like the idea of replacing these motors and insisted on taking them to a motor rewinders...who then confirmed the windings were open and informed the customer that he couldn't rewind them for less than the replacement cost £350.00 each which obviously he has to pay now.
The 16th ed. wiring regulations does not allow motors to be controlled via the same switch either because motors are not allowed to share a protective fuse.
Is the problem increased because one of these motors is driving right handed and the other left handed, or doesn't it matter
No, the left hand/right hand makes no difference. You cant parallel the motors as the manufacturer says!
Each motor must be switched independently of the other.
