Identifying and then modifying 3phase motor windings 2

[mark-ellis]

HI, I'm In Australia, so we have 240v single phase and 415v 3 Phase power.
I have a 3phase motor rated for 415v. I can't identify whether it is wound for Delta or Star.

There are only 3 wires coming out of the motor (it is NOT a dual speed motor)not the usual 6 that I am use to here in Australia.


I would like to firstly identify whether the motor is wound for Delta or Star (I suspect star, but can't tell.

I would like to change it to Delta to run on 3phase 220v with a VFD as I do not have 3 phase power at my house.

Here are an image of:
1. the connector block (the input is on the bottom, there are only the three black wires at the top that go through to the motor body (they can be seen in the 3rd image.
2. The nameplate on the motor.
3. the windings and junction of the 3 black wires.

The end result is I'd like this to be able to be wired in Delta 240v 3 phase, which means I'd need to change the Junction box, and have 6 wires coming out of the motor instead of the current 3.

Can somebody walk me through how I should be going about this please.

Cheers

 

[waross]

Look at the jumpers.
Star: Each supply lead will connect to one winding lead.
Delta: Each supply lead will connect to two winding leads.
Star: One jumper splice will connect three winding leads.
Delta: No other splices.
Star: One jumper splices.
Delta: No jumper splices.
OR
Star: Each supply lead will connect to one winding lead.
Delta: Each supply lead will connect to two winding leads.
Star: Most jumper splices will connect two winding leads. One jumper splice will connect three winding leads.
Delta: All jumper splices will connect two winding leads.
Star: Four jumper splices.
Delta: Three jumper splices.

--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[mark-ellis]

So does that mean that I need to open up the part of the winding wrapped in brown paper (underneath the cable tie) in the 3rd picture?

 

[zlatkodo]

mark-ellis
It's hard to see from here but for start check marked connection . Could be Y point.

Winding Redesign

 

[edison123]

It looks like Wye connected winding. Remove the wye/star connection inside and bring the 3 leads (A2, B2 & C2) to the terminal board and connect in proper sequence of A1B2, B1C2 and C1A2 to get 220 V delta.

Wouldn't be cheaper (and definitely better) to get a 3 ph 415 V supply to your house instead doing the winding conversion+VFD route?

Muthu

http://www.edison.co.in

 

[mark-ellis]

It's north of AUD$3k to get 3phase to the metre box including a re-wire of the metre box, Plus the 25m of wiring to the workshop sub box and 3phase power points installed there as well, so no the motor conversion is a heap cheaper, the VFD is around AUD$450

 

[mark-ellis]

zlatkodo , yes, that is the Y point. I have pulled it apart and checked.

Here's a picture:

I have cut the Y join and confirmed with multimeter that this is the Y.

 

[zlatkodo]

Separate this Y point and draw 3 leads out as Edison wrote.
Mark the existing 3 leads with A1; B1 and C1. Use a multi-meter to determine the corresponding leads A2; B2 and C2.
This way you get six leads out that you need to connect in a triangle as is already described .

Visit us

 

[davidbeach]

If you’re going to feed single phase to the VFD to get three phase, why not just use a transformer to step up to 415 and feed the VFD with that?

I’ll see your silver lining and raise you two black clouds. - Protection Operations

 

[mark-ellis]

Ok, apart from labelling the connections, I have separated them out, soldered extensions, insulated with fibreglass cable insulation, cable tied up the section I have opened, and sprayed with non-conductive varnish.

 

[zlatkodo]

Hi, Mark-Ellis,
Sorry, I haven't seen it before.
You should not use such plastic ties. They are unlikely to withstand the operating temperature of the motor.
By the way, if your application is not very demanding, you can use some of the cheap Chinese VFD-s with a price tag of around 110USD (4 kW) instead of AUD$450.
Contact us for a link.

Winding Design and Motor Repair

 

[mark-ellis]

zlatkodo there is already some cable ties in the motor, what would you have used instead?

Also, I was intending to buy a HY 5.5kw VFD for the motor. They seem to run around AU$380 AUD on Aliexpress.

 

[dArsonval]

It depends on the material integrity or temperature rating of the "plastic" tie.
Some wire ties withstand considerable temperatures. Some melt like a candle.

John

 

[Sparweb]

Nobody is going to know what temp the zip-ties will melt unless they're using the Military-grade kind (i.e. too far down that rabbit hole).
The question isn't really about melting - well before that it softens and sags.

Better replace the zip-ties with a lacing cord like the kind already used in the motor. It should match the temperature rating of the stator insulation. First google hit:

https://wfilament.com/industrial-products/stator-lacing-tapes-cords/

 

[mark-ellis]

So what sort of temperatures are we talking here 60c or 250c? Or higher?

 

[zlatkodo]

Maximum temperature of winding for your motor, according to nameplate, is 120 deg.C, but class F materials for maximum winding temperatures of 155 deg.C are commonly used lately.

 

[mark-ellis]

Thanks for your help guys. I have opened it up and replaced the cable ties with some Kevlar twine that I recently got. I'm going to have to pull it apart again as I'm sure I have a bad bearing on the front of the motor - there's a slight click as the bearing rotates when not under load - I guess that'll get a lot worse when it's under load...

 

[Sparweb]

Sorry to hear that. One problem solved, only for another to show up. No, bearing noises don't get better on their own.