Thread: Am I mad

I'm assuming everyone caught the drift (unless I've misunderstood something) that Welder is attempting to run his motor which is still wired 415v star off a 240v output VFD? Now I'm not sure what exactly happens when you do that, but I'm sure that there is a reason we're always digging the star point out of our motors...

Originally Posted by Jekyll and Hyde

I'm assuming everyone caught the drift (unless I've misunderstood something) that Welder is attempting to run his motor which is still wired 415v star off a 240v output VFD? Now I'm not sure what exactly happens when you do that, but I'm sure that there is a reason we're always digging the star point out of our motors...

Yes, I've been following the project, and the power will be reduced at 1/2 voltage, but it should still work just fine at reduced power.. I'm pretty sure the current problem has nothing to do with reduced voltage.

Ray

Well I reset the Vfd to factory setting and it works. I have stalled the wheel once but you can't really notice the decrease in power. I spent the afternoon making a diamond dresser for it.

Hi Andre,

Glad to see you got it sorted.

I was asking my son-in-law, ( the motor rewinder. ) he says the standard charge out rate for a star to delta conversion is 1 hours labour, and for the place he works at, that's $82.50 per hour. The actual job usually takes about 1/2 an hour.

Ray

Good to see it working. I would say though that unless you were taking a .010" cut or something as crazy that you should not stall the motor.
The offer still stands to come down and do it here when we can line it up.

Cheers,
Ew

Originally Posted by RayG

Hi Andre,

Glad to see you got it sorted.

I was asking my son-in-law, ( the motor rewinder. ) he says the standard charge out rate for a star to delta conversion is 1 hours labour, and for the place he works at, that's $82.50 per hour. The actual job usually takes about 1/2 an hour.

Ray

Having done a Star/Delta conversion myself recently I would say that it is impossible to do it properly in half an hour, even one hour would be pushing it as everything has to be laced up and re-varnished per good standard electrical practices.

Lex.

Originally Posted by Techo1

Having done a Star/Delta conversion myself recently I would say that it is impossible to do it properly in half an hour, even one hour would be pushing it as everything has to be laced up and re-varnished per good standard electrical practices.

Lex.

Nope, half hour is plenty of time, they do a full rewind in around 4 hours. All internal joins are brazed with lpg/oxy, fibreglass sleeve, nylon laced and varnished. When you have a workbench set up with everything at your fingertips, and you've done it a hundred times before, you get pretty good at it.

Ray

Andre is visiting on Saturday so we can pull the start point. I have marked a likely starting point on the photo. Anyone spot anything i'm missing?

Ew

Looks like a good starting point Ew. This one seems to have lots of internal individually sleeved connections. Can you see why?

Cheers,
Joe

Well I am headinv up to Ueee's place now. Should be interesting as I lost his adress so hopefully I get there :doh:

I can PM Ewans address to you if you like Andre.

Phil

PM sent anyway

I finally got out of bed this morning in time to send Andre my address....

Anyway, the conversion was plain and simple, not sure why the rewinders wanted so much. The spot i circled was the one, simple cut the wires out, split and then add the new wires and cover with woven spaghetti. Some twine and lacquer and it was done. The reason the rewinders may have been touchy about it is the motor and spindle housing/spindle are all one piece. You cannot take the rotor out without pulling the main spindle bearings out etc etc. Not that the rotor needed to be removed to do it.....

Cheers,
Ew

Well I got the motor put back on,dressed the wheel and had a test grind there's a 0.004 mm deviation.

Hi Andre,

Good to see it's up and humming along.. you might want to take a lick off the chuck and you should get that last 4 microns with a bit of care.. cleaning is important...

Ray