Reversing star-delta motors

Can you Swap the phases at the source panel?

Please assume this is not possible - perhaps there are other motors connected to the source panel elsewhere, and this is the only one running the wrong way round?

But there must be a point where the 3 wires from the supply enter the reversing starter. Can you not swap 2 of them? This would not affect anything else.

Cheers....Codey

Dear wareagle,

The answer is YES. You have to take care to change the connction at the output side of the switch, in the MCC.

DHAYANANDHAN.S

Hello PWSlack,

I can only hope that the motor leads are identified in the terminal box. It sound like you have a star-delta starter switch in your MCC. If so, then it is still as simple as swapping two phases, it is just that each phase has two wires. It should be something like this: U1-V2 (L1), V1-W2 (L2) and W1-U2 (L3). Obviously, the leads should be rung out back to the MCC to absolutely ID them, etc., but judging from your previous posts at CR4, I don't think I have to tell you that.

It is best to make no assumptions, and to phrase the reply in a way that the new CR4 reader may understand and learn from.

Please continue with the explanation!

First things first, mark all your cables and do a quick sketch of how it is now! Now you want to identify each bobbin! This is easy to do with a continuity tester! Now change the two marked cables that were on the first bobbin to the second bobbin ( and at the same sides of the bobbin!) and the two cables from the second bobbin to the first bobbin! ( see diagram at bottom).The junction box on the motor is the ends of the three bobbins! These bobbins can be connected together at one end to form a star connection or the two ends of a bobbin are bridged to for a delta connection! With the Star-Delta, both ends of the bobbin are taken back to the MCC where they are connected one way then the other! After you have connected up the motor again in its new configuration, I would advise doing a quick bump test in both star and delta to make sure they are both going the same direction!

A bump test is where you start the motor for the briefest amount of time to see which direction it is going in! A press on the start button followed quickly by a press of the stop button!

Remember to mark all the cables both going to the motor and coming out of the motor! It makes life just that little more easy!

Hope that helps!

Remember do a bump test! And check to see if your getting the right amp readings!

I like your explanation, and your diagram is better than I can post. However, your bottom diagram has some interesting labeling. Shouldn't the top row be W2, U2, V2 and the bottom row be U1, V1, W1 ? Everything else about it work for me except the labels.

I found this diagram: http://www.johnson-pump.com/Horticulture/quickstart-motor.htm

It's the old you say potato, I say potato thing!

I found this one!

Best thing to do is scrap my last post ( I want to think about it a bit more!)until PB gives us a circuit dgm of the layout he has! That way we can all work with the same thing! I don't think my last idea would work TBH! I'll vote it off topic!

Revised edition!!

Depending on the conections in the terminal box!

Just check what bobbin goes to what terminal first unless it's written on the thing!

That looks like the right answer.

You should not have voted it off topic. In my opinion, it was a good post with relevant information.

I miss quoted and said that the two ends of the bobbin are bridged when it is in fact the bridging in the delta formation connects the bobbins together one after the other so to speak! I got my two terminal box configurations mixed up so I prefere to off topic it and start again!

I would still perform the bump test in both star and delta though!

OK then, I will plough on... but I do have to make some basic assumptions, such as it is a star-delta starter, and that your motor is likely an IES specification as compared to US, such that the leads will be identified U1, U2, V1, V2, W1, and W2.

I understand your dilemma regarding drawings. Besides, it is my preference to alter rotation at the motors as compared to altering rotation at some point in the distribution system, but I digress.

You should be able to examine the wiring in the MCC to determine which motor output terminals are A, B and C phase. Tracing this out to the motor, you should be able to identify which motor leads are connected to A, B, and C. For example, you may find that U1-V2 goes to A, V1-W2 goes to B, and W1-U2 goes to C. You can swap any two phases, but I'll use A and C here; exchange V2 with U2, and exchange U1 with W1. This will reverse the rotation of you motor.

Go back to wareagl'es first post, but don't misinterpret it.

You don't need to swap out the leads for the entire plant! Swap out 2 of the LINE leads as they terminate on the STARTER.

Clock wise direction

R phase from starter/MCC to Motor- start w1--------------- finish w1 to Y Phase of Starter

Y Phase from starter/MCC to Motor-start w2--------------- finish w2 to B Phase of Starter/MCC

B Phase from starter /MCC to Motor-Start w3-------------- finish w3 to R Phase of Starter /MCC

Anti Clock wise direction

R phase from starter/MCC to Motor start w1--------------- finish w1 to B Phase of Starter

B Phase from starter/MCC to Motor start w2--------------- finish w2 to Y Phase of Starter/MCC

Y Phase from starter /MCC to Motor Start w3-------------- finish w3 to R Phase of Starter /MCC

Therefore inter changes are

1) Retain r Phase connection in Start w1 and Finish w3.

2) Inter change finish w1 and finish w2

3) Inter change start w2 and start w3.

I have done this practically in one of the sites in Chennai,India No problem ,within 30 minutes I have recommissioned the motor.

Hi, this is easy, Just swap two of the supply leads that run into the box (control). This reverses the the start connection AS WELL as the run. Who cares about all the wires after the input! Oh, by the way, I am qualified to give this response.

Better clarify, swap two conductors to the input of that motor circuit. Perhaps their are other motors running from the main control box. But otherwise, it's not hard at all. Find the supply to the main contactor, swap two conductors, presto!

<...swap two conductors to the input of that motor circuit...>

........is not possible, for the reasons stated!

I cannot envision a situation where this is not possible. AT SOME POINT there are 3 conductors entering the Star-Delta motor starter. If you swap the leads at that point, the motor will reverse.

GA and I agree....

That's what I said in #16..........

Codey

If its not physically possible to follow some of the good advice here, just cut the supply cable to the starter box and put a suitably dimensioned connector box at the cut and swap any two phases with each other......

Mark box accordingly......

Did I wrongly assume that this was a "real" problem?

Hi , swop over any two L1,L2,L3, incommers at the isolator