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By guineafowl21
#1305169
I bought this fine, old and very heavy machine for £150 (seller’s picture):
E1A2C5D9-2FBA-485D-B7A5-011ED3DA8457.jpeg


It’s a pre-1970 model, three phase and wound permanently in star, so required 3ph with 400V phase-phase, rather than the 3ph/230V ph-ph which a normal inverter drive would provide.
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By guineafowl21
#1305174
After opening the motor up, I had a dig in the windings and found the star connection:
00183DA2-F472-4F42-983F-C0D59213E0E6.jpeg


Close up:
98DA2653-95C6-4945-B1AC-C3EB8A9B04C5.jpeg


I brought the three new wires out the the paxolin panel:
092B5AD3-7CED-4A42-8B23-0EFFC6F8E82E.jpeg


After labelling the connections, I could then configure in delta with straps:
EF1B0666-20A7-4EFE-81AA-DCB5EA6087FD.jpeg


A cheap and cheerful, 1ph-3ph inverter later, the mortiser was working... (sorry for the sideways look - it’s the right way up on my computer:
2A28F150-1A65-42C8-B3FF-A5939105D3EF.jpeg


...and makes short work of mortices, even through knots!
04428F9C-5D40-456D-B3F2-0C76709B1323.jpeg
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By guineafowl21
#1305226
Ttrees wrote:Good show =D>
Never heard of paxolin before, is it the only thing suited for the job?

Thanks for posting
Tom

Paxolin is the name, I think, for that brown insulating board found in older electronics. I’ve encountered similar stuff restoring vintage radios.
By J-G
#1305256
Ttrees wrote:Never heard of paxolin before, is it the only thing suited for the job?

Paxolin is a Phenolic Resin laminate similar to Tufnol which is, as far as I am aware, a newer product. I remember Paxolin from the 50's but haven't seen it mentioned recently. I carry sheets of Tufnol which I use for all manner of things. Currently working on a Clock cum Tellurium using 3mm thick sheets to hold the bearings for all the gearing spindles.

The big benefit (for me) is its dimensional stability, though the electrical insulation is as important to many other users.
By weekend_woodworker
#1305657
Sorry to be dim, but can I check that the reason to change the wiring was that so a normal inverter would work with it, not to avoid the need for an inverter? I assume that would require a complete new motor or for the existing to be completely rewound?

Thanks

Mark


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By guineafowl21
#1305749
weekend_woodworker wrote:Sorry to be dim, but can I check that the reason to change the wiring was that so a normal inverter would work with it, not to avoid the need for an inverter? I assume that would require a complete new motor or for the existing to be completely rewound?

Thanks

Mark


Sent from my iPhone using Tapatalk

The motor was configured in star, which is the three windings connected in a Y shape. The three phases would be fed in at the three ‘outer’ points, and there were three terminals to do this. The central point of the Y, where the three windings come together, was hidden. It was designed to have 400 (ish) volts between each phase.

A normal inverter drive can produce three phase from single, but with only 240V between each phase. In order to accept the lower voltage, the windings must be in delta, or a triangle. So the hidden central tri-connection (‘star point’) needed to be brought out as three more separate wires.

Dual voltage motors have all six terminals already, so it’s a simple matter of altering bridges between terminals to choose between star or delta.
By weekend_woodworker
#1305788
guineafowl21 wrote:
weekend_woodworker wrote:Sorry to be dim, but can I check that the reason to change the wiring was that so a normal inverter would work with it, not to avoid the need for an inverter? I assume that would require a complete new motor or for the existing to be completely rewound?

Thanks

Mark


Sent from my iPhone using Tapatalk

The motor was configured in star, which is the three windings connected in a Y shape. The three phases would be fed in at the three ‘outer’ points, and there were three terminals to do this. The central point of the Y, where the three windings come together, was hidden. It was designed to have 400 (ish) volts between each phase.

A normal inverter drive can produce three phase from single, but with only 240V between each phase. In order to accept the lower voltage, the windings must be in delta, or a triangle. So the hidden central tri-connection (‘star point’) needed to be brought out as three more separate wires.

Dual voltage motors have all six terminals already, so it’s a simple matter of altering bridges between terminals to choose between star or delta.

Thank you, that is really helpful. One last question of clarification, does that mean that a dual voltage motor will still require an inverter to create 3 phases at 220volts?

Many thanks

Mark


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