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3 Phase Motor Starters

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lordedmond:
Yes Phill
Looks like you played with the same old stuff as I did , the most brilliant thing we had was in the elect. Workshop was a Mercury rectifier looked like a glass ball with glass horns with curly wires on when on you could see the arc dancing on the pool ,bet it was not good to look at

We had some very big stuff to look after inc 1.5 mega watt induction furnaces and 2 mega watt fans

I have polluted the op thread to mutch so I will wait for more info from him

Stuart

RussellT:
Hi Phil

Thanks for that walk through servicing the starter.  It gives me a lot more to go on.  The starter must be an electrical hold on type as the on switch doesn't stay in place.  I'll have a closer look at the wiring - I wanted to take the redundant wiring to the coolant pump out anyway but I wanted to check on the PCB issue first, so I'll check on what the insulation is like.

The starter actually looks quite clean inside, even though the lid is cracked.  The crack is along the edge so the seal is still held in place.

Thanks for the caution over the oil Stuart I will take great care  to avoid it.  In fact maybe I should get the lathe's owner to do that bit as he claims to have no sense of smell.

Thank you both for thinking of popping over.

I probably won't get another chance to have a look until next week but I've got some other issues to think about first.  The main fusebox for the 3 phase supply is fitted with three 15 amp fuses but he also wants to run a single phase 5.5hp table saw so I'm trying to work out the easiest and cheapest way to upgrade one of the fuses - but I probably need to go back and collect a fuse holder to take to the shop.  There's no hurry though.  The lathe has been sitting there for 20 years.

Don't worry Stuart it's on topic as far as I'm concerned.


--- Quote from: hermetic on March 20, 2015, 11:45:13 AM ---Anyone trained later than the early eighties will run away screaming when they see this equipment!

--- End quote ---

Some of us are made of sterner stuff - or didn't realise that was an option. :lol:

Russell

RussellT:
This is an update on how this has worked out so far.

The fusebox was totally obsolete and we couldn't get a new higher rated fuse.  The man in the shop said "That's so obsolete I've never even seen one".

However a little work with the lathe enabled us to use a different (physical and rating) size fuse. (Picture attached).

Safety was improved by fitting a box with RCD and single and three phase sockets (visible top right in one of the lathe pictures attached).

The starter as predicted was a bit troublesome.

I connected it all up and turned on the power - nothing happened.  This was good - no loud bangs or flashes.  The lathe lamp didn't come on - but that wasn't a surprise the bulb has been sat there 20 years or so - (although I had changed the wiring).

I tried the starter.  It buzzed and the lathe lamp came on and went off again.

I had a look in the starter and I couldn't make it latch manually.  Further investigation found a spring out of place - with that corrected it would latch manually but dropped out when the power was turned on.

Investigation with the meter showed one phase with no power.  Fortunately having uprated one fuse for the single phase circuit we had a spare fuse.  With that fitted we tried the starter and the lathe motor sprang into life - sounding exactly as it used to 20 years ago (or so I was told).

I'm not quite sure how the two live phases managed to blow the bulb as it was connected to the dead phase but they did - through motor or starter I assume.

We didn't actually try the lathe deciding it was probably better to check oil levels etc first so I still don't know if I've got the motor running in the right direction.

I've included a couple of pictures of the lathe for those who were interested.  It's a Churchill CR 12".

Russell

mexican jon:
Nice looking piece of proper machinery that is  :thumbup: :thumbup: :thumbup:

hermetic:
The bulb could be a 12v or 24v one running from what was known as a Lovolight machine light transformer, which is a 3 phase primary with a single phase secondary, so if two phases were present you would get a voltage of sorts at the output. Keep at it, you are making good progress!
Phil

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