Wiring 5.5kW motor to DELTA - Help

[Smouser]

Bottom line up front: I am trying to rewire a 5.5kW motor to DELTA, but I am confused about the winding wiring.

Background: I have rewired a few older motors which were 'STAR' only before by opening them up and finding the STAR point. Running new wires from the STAR point to the terminal box and then connecting them up to DELTA.

The motor:

5.5kW, 400V motor connected in Y (STAR).

Unfortunately, only three wires are coming from the windings.

So I pulled the motor so I could open it up.

The rear terminal box is for an electric fan (operating on 220V).

I removed the pulley and the rotor, and this is how the motor looked inside.

Rear

Front

It looked to me like the STAR point was most likely at the rear of the motor (where the U.V,W wires are coming from), so I snipped some bindings off and thought I found the STAR point.

The problem:
Why are there two wires in each sleeve instead of one? All the previous motors I have rewired had only one.

When I check continuity between any pair of the above wires and U, V, or W in the terminal box, they all show continuity.

I am stumped.

Can somebody shed some light?

 

[Seadog]

Have a look at one of the original wires, where it is connected to the winding. You'll probably find that it also has two wires.

 

[Smouser]

You were correct!

Once I pulled those wire loose (the varnish or whatever they used are SUPER strong) I could see W1 (red), V1 (Green) and U1 (Yellow) each have two wires going to it. Inside those two sleeves, there are 2 wires again.

In total, I have 12 winding wires now

This is how the V1 connection looks like.

Two pairs of wires joined to the V Green lead going to the terminal box.

So they question now is, how do I wire this all up?

 

[Seadog]

 

[Brad93]

I'm thinking there may be two wires because the option would be there to increase resistance by having the coils in series.

So you might currently have two coils in parallel joined at both ends of the coils.

To put it in series for more resistance, you'd unsolder one end of each coil.

I haven't got any paper to hand nor my book with the drawings.

Americans call this 9 or 12 wire three phase motor if I remember correctly

 

[Seadog]

There are motors with paralleled star phases, but the gauge of wire at the star point should be double what it is (given that there are three more commoning points for the other ends of the twin coils).

 

[Smouser]

Thanks. Calling it for tonight. Hopefully, I can figure it out with some help during this week.

@Pete. knows a fair bit about motor wiring too I think.

 

[Agroshield]

In total, I have 12 winding wires now

You have six wires where the star point was.

You have twelve wires where the coloured tails are joined.

You need to work out the logic between the two.

Separate the four on the green wire and see what is their relationship to each other (continuity and resistance) and the same thing to the star point wires.

Peel off the rest of the binding tape and maybe sharpie mark the yellow wires until they disappear. If you can identify how the four wires joined to the green exit the other end of hte yellow sleeving, that might help.

Have a real good second look at the front just to confirm there is nothing hidden there.

 

[Smouser]

Thanks.

I think you are correct. If I get a chance tonight, I will remove the rest of the bindings on the rear of the motor to check if there are any further connection points.

It does not look like there are any connection at the front of the motor. However, I can't be 100% sure without removing the bindings. I will make a decision to remove the binding or not after having a good look at it again.

 

[Agroshield]

I will make a decision to remove the binding or not after having a good look at it again.

Work with the four on the green plus six at the other end you already have exposed. If you can deduce something useful from what you have, you can open the red to confirm that theory. If they tell you nothing, then you can decide on further cutting of binding.

 

[Smouser]

I had a long day at work.
Don't have the will or mental capacity to do too much tonight.

New development:
I have removed the rest of the bindings on that side of the motor and had a proper look at everything.
Found one more 'STAR' point
(my thumb is pointing to the newly identified 'STAR' point on the photo below)

It is the same as the other 'STAR' point. Three wire sleeves, and each sleeve has 2 wires inside.

Summary:
In total, there are 12 winding sleeves, each with two wires inside them. I am assuming those two wires in each sleeve are the same.
If that assumption is correct, it means I have 12 winding ends.

I have heard of some motors which has 12 wires in the terminal box (mostly American motors).
Once everything is identified correctly, I can pull 12 wires into the terminal box and make all the connections there (lots of testing and head scratching before I get to that point).

I think the motor is currently wired like the circled section.

 

[Guineafowl]

Looks like you have it right. To verify, test each of the three (paired) original wires - each of the pair should go to a different star point.

Main concern is, if you’re right, the motor is plated for 400V, and configured in ‘low voltage’, suggesting it’s a 400/690V. Is your aim to run it on 230V?

 

[Smouser]

Yes the aim is to run it on 230V.

Are you saying that the two wiring configurations (STAR and DELTA) in the image below will both result in a 400V motor?

If that is the case, it has all been a wasted effort

 

[Guineafowl]

^ I think so, but don’t panic just yet. Sit down with a meter, beer, and masking tape and double-check what you’ve got.

Anyway, more investigation needed

EDIT: hang on a minute. I’ve redrawn the windings in your diagram for just the two low voltage configurations. If it’ll take 400V in parallel star, left, then it should accept 230V in parallel delta, right:

 

[Seadog]

 

[Smouser]

View attachment 499105

I don't think mine is the same as that.

I have two internal starpoints on my motor. On your diagram it looks like only one starpoint.

 

[Seadog]

True.

 

[Seadog]

Reading through this would suggest that what you have is a low voltage "Y" configuration. Inferring that it could be configured in a 400v or 690v "Y" configuration.

Motor-Lead Connections – Basic Motor Control

opentextbc.ca

If it runs in this configuration, I can't see an immediate problem in configuring it in a dual-Delta config, which will be 240v.

 

[Guineafowl]

Oddly, I can’t find any mention that a 400/690V motor can be run on 230V. But going from the basics, looking at my left-hand drawing as the motor is now, 400V is across two parallel pairs, in series but 120 electrical degrees apart. So the voltage across each pair will be 400 / (sqrt3) =230.9 V.

So, putting 230V across each pair in parallel delta should work. I’ll have to have a think about whether the current and power will be affected.

I think the power will be the same, and the current increased by (sqrt3), so 10.9 x (sqrt3) =18.9 A.

 

[Seadog]

Yes, ball-park will be a doubling of the current.
Care needs to taken not to get any coils in anti-phase, but it should be a relativey simple task.