Dismantling a Brooks 3ph motor

[cheb]

Here goes.

Started like this:



Pulley removed and then wiped down with a kero-y rag, I tried not to remove too much patina.



Studs out or nuts off:


The grease at the far end is a bit dry:


This is as far as I got, the other parts are scattered across the bench:


It all seems in reasonable order. Mantling will be a reverse of the above plus new grease.

 

[Fastdruid]

I'm regretting the fact I chucked my old motor now. You could have had my non-broken pulley off it.

 

[Fastdruid]

So now you need to find the star point. Look for a "lump", carefully tease it out and split it, add some extension wires (with insulation) to each, tie it all back up and re-varnish and run them to the junction box.

Obviously as there are only three connectors in there you'll need to manually "make" them connections rather than have the nice 6 terminals with movable links that 240v/440v delta/star motors have but it's fairly straight forwards once you've got them out.

This was the plate off mine which was converted (before I got it). It's a lot older than yours.

 

[Seadog]

The star point is probably at the terminal box end of the motor.

 

[Newlands]

The star point is probably at the terminal box end of the motor.

Yes, and if @cheb posts a photo from that end we can place bets on where the star point is.
I did a Harrison lathe motor here https://www.model-engineer.co.uk/forums/postings.asp?th=111109

 

[cheb]

More photos:

Empty terminal box:


This sleeve looks to have one wire:




This has two:


As does this one:


This one has three:

 

[Pete.]

The one that has 3 wires together will be the star point. The others are just joiners where they have linked 2 sets of windings

 

[mtt.tr]

They can be a bugger with these motors.

As pete said it will have 3joined together

 

[cheb]

The one that has 3 wires together will be the star point. The others are just joiners where they have linked 2 sets of windings

That's what I thought. Slit it. separate the wires and run them back to the junction box then. Having labelled the ends correctly. Any particular grade or type of wire. Why type of string to re tie? And what type of varnish?

 

[Seadog]

Everything that you could possibly want is here - https://brocott.co.uk/electrical-insulation/

 

[Agroshield]

Having labelled the ends correctly. Any particular grade or type of wire. Why type of string to re tie? And what type of varnish?

It does not matter too much about labelling them just now. Just do a continuity test when you have finished - each existing wire should have continuity to one and only one new wire and to nothing else (e.g. any part of the stator or motor body). If you have some of the high temperature wire (fibreglass insulation, as found in the back of cookers) that is best. The siliconised fibreglass sleeving you get with halogen downlights is good in this application. Cotton string is better than nylon (better heat resistance). For the very little you are to disturb things, polyurethane varnish would do, or even nail varnish. All it is really doing here is gluing everything together so it does not vibrate and chafe. As long as you insulate the join between the winding and the new tail, it should be OK.

 

[cheb]

Thanks, I'll be down to the tip tomorrow raiding old cookers, cotton string I've got, and some nail varnish in a lovely shade of pink.

 

[Seadog]

The one thing you need to ensure is that you know which ends are the originals and which are the new. If you get a winding reversed the motor will not be very happy. Much easier to label everything as you go along such as, for example: A1 and A2, B1 and B2, C1 and C2. When you reconnect the wires in delta a "1" will always go to a "2."

 

[cheb]

How stupid would it be use chocolate block for the motor terminals?

 

[Agroshield]

How stupid would it be use chocolate block for the motor terminals?

£8.50. https://www.ebay.co.uk/itm/394046709014

Use them if you need to, just to get it running, but it's not the best long term and makes it difficult for someone in the future to put it back to star.

 

[Pete.]

You don't need a different connector block, just bring the tails out to the same place and double-stack the rings on the three posts.

 

[Agroshield]

...double-stack the rings on the three posts.

Triple stack if you count the incoming phase wires. Only saying this so he can check there is enough length for three wires plus washer and nut.

 

[cheb]

This'll have to wait for a bit now as I'll away for a work for a couple of weeks.