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Star delta motor running in reverse
GFaw
7 Posts
Question
cb2b3ed0d9721889dcb921ed793efac0-huge-20
Star delta connected as above. The phases are in correct rotation (have a phase rotation relay in control circuit). Motor is running in reverse, but I can't for the life of me remember how to reverse the motor at the motor terminals. I can't just swap the MCCB feed so how should I alter the wiring at the terms to make the above work?
6 Replies
mapj1
4444 Posts

That is interesting I'd expect the 6 terminals to be  

U1 U2

V1  V2

W1 W2

Where U1-U2 is one winding, V-1-V2 is another.

having said that it may be so you can do this with simple links, though you are using the Y D starter to do the links

 

What is the make of the motor ?

However, assuming it really is as you think, but to be safe do please check that first with a meter on  ohms, 

swap the wires  U1 with V1  and the wires U2 with V2. 

(or indeed any winding that is a 1-2 pair for any other winding that is a 1-2 pair)

It would be cleaner to swap any 2 phases at the point they enter the machine.

Mike

Just switch L1 to V1 and L2 to U1

mapj1
4444 Posts

Just switch L1 to V1 and L2 to U1

be careful - that works with a motor wired with fixed links, but if you exchange the L1 and L2 to the ‘1’ ends of a pair of  windings, but the supplies  to the ‘2’ ends of the  of the same windings are not also swapped, that will reverse it for starting in star, but as the starter is supplying both ends separately, you can have a situation where once up to speed the right way, and switched to the delta connection it may then try to reverse and go round the wrong way - which is likely to be very impressive/expensive.

Of course if the starter is supplied from a point after the L1- L2 switch, then you do not need a second swop…

Mike.

Eddy_Kee
14 Posts

It would be cleaner to swap any 2 phases at the point they enter the machine.” 

I agree with Mike. It is safer to swap the 2 phases at the MCCB than do at the induction motor. I use to do this rectification for reversing a Star-delta motor. The motor rotated reverse as I need.

Cheers

Eddy

GFaw
7 Posts

Yes, it simplest but not suited to my application. We are doing a common panel that is designed to be attached to over a dozen slightly varying machines, a lot of which have different makes of motors (so no guarantee that they are all wound for CW or CCW), so I want to configure all the moors so they spin the same direction as long as the incoming phases to the control panel are in the right sequence.

GFaw
7 Posts

For testing, i did this and, bizarrely, in star the motor starts in the right direction but grinds to a halt then, once in delta does a normal DOL type start in the wrong direction. Can't get my head round this at all :/

 

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