Newbie- 2-speed motor internal connections

[electrosteam]

Hi all,
The Kondia Powermill FV1 that I have just acquired is fitted with a 415Vac 50 Hz 2-speed motor.

Has anyone had any success re-connecting the internal windings to 240Vac ?

The motor has 6 wires entering the terminal box from its internals (6 windings ?).
High speed applies the phases in star arranged to provide a 2-pole flux and 3000 rpm.
Low speed applies the phases in delta arranged to provide a 4-pole flux and 1500 rpm.

To arrange as 240Vac I need to get to both ends of all the windings.
This could involve separating internal copper conductor connections - crimp, solder, weld or continuous conductor.
I figure two deltas in parallel would give me the 2-pole flux condition and 3000 rpm.

Single (high) speed resultant is OK as I will add a VSD from the 240Vac house wiring.

If anyone has already tried, is it worth it ?
Any hints ?

Happy machining,
John.

[Al_The_Man]

A few things don't seem to add up?
Does it have 3 separate windings? i.e. 3 pairs = 6 ends?
Often a two speed motor can be two separate star connected windings, 2 pole & 4 pole.
This you can tell if you have continuity between each of 3 windings.
Star Delta usually gives the same rpm but two voltage ratings.
You need to confirm if the six ends are 3 coils not two separate star sets of windings.
Al.

[electrosteam]

Al,
thanks for comments.

The motor is rated 2.5 kW/1.5 kW, near enough to constant torque.

High speed is star:
- terminals 2, 4, 6 to the line,
- terminals 1, 3, 5 connected together.

Low speed is delta:
- 1, 3, 5 to line,
- 2, 4, 6 open.

From the connections, I deduce:
- six separate 240Vac windings,
- star; two windings in parallel in each spoke of the star,
- delta; two windings in series in each side of the delta.

My motor experience is limited to re-wind of small permanent magnet DC motors and observation of the re-wind of large AC motors.
Although confident of the theory, is it wise to bite off a craftsmanship requirement I might not be able to deliver ?

My rough plan is to cut conductors to separate the coils, extend the coil ends to a larger terminal box where the ends can be re-arranged as required.
Jointing would be done with small gauge binding wire, soft solder and heat-shrink (tape ?).

A motor re-wind shop would probably weld the coil end extensions.
They may also advise the coil ends are buried too deep and cannot be accessed.

Happy machining,
John.

[Al_The_Man]

I'm still trying to figure than one out?
What is the continuity reading between all ends when completely separated?
Al.

[electrosteam]

Al,
I disconnected all the external wiring at the motor.
All 6 terminals test as connected.

I took one internal connection off a terminal.
The core(s) are stiff like it is the actual winding conductor(s) and covered in the old fashioned woven and impregnated cotton sleeving.
I tried cutting back some sleeving but would prefer to only do that once I am committed to the job and the motor is on the bench.

It is cold in the workshop at the moment (12 C (53 F) at midday, coldest couple of days in over 25 years).

I have also just discovered this thread could be in the wrong forum.
Are you able to move it to the correct forum ? (perhaps "Phase Converters and VSD" ?)

John.

[electrosteam]

Al,
Dismantled the motor and found that the cabling to the terminals are single tinned copper cores disappearing down into the middle of the winding.

To get at the coil connections to the copper cores I would have to soften the winding in an oven and bend some of the coil ends out of the way - not possible in my limited workshop.

A local motor re-winder has quoted about $AU350 to rewind the motor, plus bearings if required.
A new motor is about $AU320, but the flange mount would need an adapter plate that would itself cost a significant amount.

The re-wind seems the way to go.

Happy machining,
John.