Rewiring a 3 phase motor to Delta

[Smouser]

I never updated you guys on the project the motor was powering.

I posted the photos on imgur.



I also made a short video of the saw in action.

 

[Spectric]

Looks like new, good job done.

 

[guineafowl21]

Very nice - show us the wiring!

 

[Smouser]

What wiring?

I don't think I took photos of the switch wiring going to the VFD.

 

[OldWood]

One of the things that came up in the answers to Smouser's query on the ON/OFF switch is that the replies failed to make it clear (as far as I could see) that the switching signal is only 5 or 10v so light weight sealed (to keep out dust, etc) switches are acceptable.

Well done by the way in finding and sorting out the star point. One of the earlier posts did point out the motor rpm to poles ratios. I have a 3 phase motor that has two sets of windings - 2 and 4 so that it can be switched between 2800 and 1400 rpm. I set out to find the star points but decided that was too risky on a dedicated motor/gearbox set up and opted for a 380/440v VFD.

As an interesting aside seemingly motors of the type I have mentioned are preferred for the huge cooling fans on power transformers as a simple switch to change speed is far more reliable than a VFD.
Rob

 

[guineafowl21]

What wiring?

I don't think I took photos of the switch wiring going to the VFD.

Yes, I meant the auto cut-off switch and connections to the VFD.

 

[Brecien]

Hi all,

I recently got a three phase motor with a machine that is 950RPM (uncommon) but unfortunately it is only wired for 380/440v.

I am looking to rewire it so that I can use a VFD @ ~240v.

Would anybody be able to offer advice/guidance on where to look for the star point from a photo of the motor?

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Hi Smouser, Im restauring an old bowl lathe with one of these motors. Your post was great as I have the same type of motor I need to do the same as you. Your Photos jump from the motor to windings. Not having taken a motor apart? Im just as much interested to Know how I split the casing and pull it apart to reveal the the windings. Can tell me if I leave the pully on the shaft?After disconnecting wires at the blunt end I presume I can get a earing puller to what ever I find behind that round plate?
Any advice gratfully recieved
Cheers

 

[DRC]

Hi Smouser, Im restauring an old bowl lathe with one of these motors. Your post was great as I have the same type of motor I need to do the same as you. Your Photos jump from the motor to windings. Not having taken a motor apart? Im just as much interested to Know how I split the casing and pull it apart to reveal the the windings. Can tell me if I leave the pully on the shaft?After disconnecting wires at the blunt end I presume I can get a earing puller to what ever I find behind that round plate?
Any advice gratfully recieved
Cheers

Always ping dots on the end caps and the casing so that the reassembly is correct.

 

[Smouser]

Hi Smouser, Im restauring an old bowl lathe with one of these motors. Your post was great as I have the same type of motor I need to do the same as you. Your Photos jump from the motor to windings. Not having taken a motor apart? Im just as much interested to Know how I split the casing and pull it apart to reveal the the windings. Can tell me if I leave the pully on the shaft?After disconnecting wires at the blunt end I presume I can get a earing puller to what ever I find behind that round plate?
Any advice gratfully recieved
Cheers

Brecien, sorry I have missed your post.

Hopefully, you have sorted your motor by now.
In regards to your questions - I took the pulley off and split the motor apart to get to the windings.
4 long screws had to be removed to get the motor apart. From memory, I also had to disconnect the wires from the 'terminal box'.

Found an old photo that shows the 4 screws/bolts in the corners.

I used a puller to remove the bearings, as they are pretty cheap, it made sense to replace them while the motor was apart.