Wadkin BRA - 3ph motor overhaul and star point extraction

[guineafowl21]

The front bearing was running a little warm, and the grease channel appeared to be blocked, so I thought I’d strip the motor down and, while I was in there, extract the star point to enable star/delta dual voltage use.

For some reason, I only have some pics of the reassembly, but hopefully it might be helpful to someone.

Here is the stator, rear end. The saw stirrup acted as a very handy rotating stand for this job:

I started by measuring the resistance between phase wires, with the meter zeroed:

I then carefully undid the tape where three wires appeared to meet:

Cutting away the insulation revealed a tri-connection:

Resistance between this and each phase wire was half of the phase-phase value, so I’m in the right place:

I cut the three wires apart, scraped away the insulation from each, and tinned with solder:

After soldering on some flex, I double-sleeved with heat shrink tubing and tied the wiring back as best I could, using butcher’s string and varnish:

 

[guineafowl21]

With the end cap in place, it was time for some initial insulation resistance testing:

That was ok, so the connector box went on next:

Bearings were degreased and packed with new, and the grease channels were cleared. The rotor then slid into the front on thin threaded rods:

Which were fastened at the back:

 

[guineafowl21]

The fan is attached with a key, nut and grubscrew:

And then the end cover:

I drilled the connector plate and fitted some studs for future use for the extra three connections. Since this machine will run on three phase for now, I just labelled the wires with coloured heat shrink and connected them together with a Wago:

All wired up! After some more IR testing, I fitted the blade and guard and did a test run. Success!