Author Topic: 3 Phase Motor Starters  (Read 13736 times)

Offline RussellT

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3 Phase Motor Starters
« on: March 17, 2015, 09:09:56 PM »
I have a friend who has a lathe which he inherited from a family business.  It's labelled as a Churchill Redman 12 inch lathe but it looks as though it would swing more than that - maybe as much as 18 inches.

It's been sat in an outbuilding for about 20 years and he hasn't got around to connecting it up.  There's a 3 phase supply in the building and he's recently had some fixed wiring done so there is now a connection box right next to the lathe.

He asked me if I'd connect it up so I went to have a look.  Connecting it looks straightforward.  The cables were cut when it was taken out so it's easy to see where it should be connected.  It appears that the earth connection might have been the flexible metal conduit.

However I was having a look to see what the rest of the wiring looked like and I have a question about the motor starter.

The starter is a cast iron object about 6 inches square and about 9 inches deep with what appears to be a detachable sump and a lid secured by 3 nuts.  The lid is cracked and it's full of oil.  It was made by a company called Ellison It's similar in appearance to the ones in the attached picture.

It looks as though there's a good chance it will work if I connect it up but I was wondering about the safety of this type of contactor.  Am I right in thinking that it's likely to be full of PCBs?

Does anyone have any advice or suggestions please?

Russell
« Last Edit: March 18, 2015, 05:57:27 AM by RussellT »
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Offline awemawson

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Re: 3 Phase Motor Starters
« Reply #1 on: March 18, 2015, 02:56:14 AM »
Russell I cant open your picture as I'm on my iPad but is it possible that it is a 'star / delta' starter, and the oil is part of the delay from star to delta? I have an ancient starter on my big Shaper that uses star/delta to initially accelerate the motor but the delay there is a human one as its manual!
Andrew Mawson
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Offline buffalow bill

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Re: 3 Phase Motor Starters
« Reply #2 on: March 18, 2015, 03:20:23 AM »
Russel, I cannot open your pic. but it sounds like the starter may have been immersed in oil, it could be a DOL starter (direct on line)  suitable for 1 - 2 hp motors above this size then it should be a star delta starter. Cold still be immersed in oil. The oil should be transformer oil not PCB. PCB were usually in components not sloshing about in starters.
Hope this helps.
Helensburgh, Argyll & Bute

Offline John Rudd

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Re: 3 Phase Motor Starters
« Reply #3 on: March 18, 2015, 03:27:16 AM »
My advice, fwiw, feet yourself to Machine mart or better still Ebay and get yourself a combined starter/ overload combo......suitably rated for the motor of course.....Run a separate earth, don't rely on the conduit....
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lordedmond

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Re: 3 Phase Motor Starters
« Reply #4 on: March 18, 2015, 03:47:47 AM »
Test or get tested the motor for earth leakage and phase balance before you connect it up

Earth test to at least 150% of line volts

Stuart

Offline RussellT

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Re: 3 Phase Motor Starters
« Reply #5 on: March 18, 2015, 06:26:44 AM »
Thanks for the replies so far.  I'm sorry about the picture.  I couldn't open it either. :doh:  I just downloaded it to give you an idea what it looked like.  I've done it properly this time and reuploaded it above and now I can add a link to it in this post, so here it is again.



Is that anything like the one you have Andrew?

Thanks Bill I feel a little bit more comfortable about PCBs - though I understand transformer oil is often contaminated - but it's probably never been topped up. The motor is certainly more than a couple of horsepower - I can't see a rating plate as it's completely enclosed within the cast iron base of the lathe.  I think I need a mirror on a stick.

John, I wasn't going to rely on the conduit as an earth - I was amazed that there didn't appear to be anything else.  In fact I'm thinking about adding another earth wire back to the supply company's earth.  The fixed wiring has been done with 4 core SWA cable but uses one core as the earth.  If I used that core for a neutral I could also get the machine light working.  I could rely on the armour for the earth but I'd be happier with an additional earth wire.

Stuart - I'll talk to an electrician friend about earth and earth leakage testing.  I'm also considering adding an RCD. :zap:

I'd still welcome any other comments now you can see the picture.

Russell

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lordedmond

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Re: 3 Phase Motor Starters
« Reply #6 on: March 18, 2015, 07:04:08 AM »
By ek Russell
That starter is a blast from the past I serviced those during my apprentiship I now 67 so you do the maths

They are oil filled as the contacts work in the oil bath , which is transformer oil vegetable based and stinks to high heaven

As the motor is a star delta wound one I would dump that starter and fit a VFD ,not to get the over speed but give a soft start , and no I did not miss the three phase supply that is installed ,but you can get three phase in and out units , failing that get a modern star delta starter with correct over load coils , best talk to your sparks as it's difficult to advise without hand on.

I did my time in heavy power with turbines up to six mega watt and motors to 3000 hp at 11kv

Have fun and make sure the machine is correctly earthed as per current regs
Stuart

Offline dawesy

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Re: 3 Phase Motor Starters
« Reply #7 on: March 18, 2015, 09:10:26 AM »
Any pics of the lathe itself?
I have a churchill redman but mines a 7-cm
Be interesting to see if it's similar to mine. Mine has a 12-15" swing I'd estimate ( never actually measured it.
Lee.
wishing my workshop was larger :(

Offline hermetic

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Re: 3 Phase Motor Starters
« Reply #8 on: March 18, 2015, 04:05:55 PM »
I also have some experience with Ellisons, albeit a bit bigger ones than that one, can you post up a picture of the motor, both ends especially, and a close up of the top of the starter to see what is on the top, there is usually a brass plate with the type and details attached to the oil tank, usually at the front. I wouldnt be at all suprised if this was a resistance starter for a slip ring motor, and unless this is a huge lathe, which I dont think it is, you may be better off changing the motor for something else more economical to run, as it wont be that efficient. I have just read the OP again, and I gather this motor is inside the machine. Has this starter ever been used to start this lathe, because if it hasn't the chances of starter and motor being compatible are fairly slim. If the motor is a plain three phase connected in star, and the starter is a direct on line one, then it should work, provided both starter and motor are in good condition, but I wouldnt put power on to the starter till you have dropped the tank on the starter and checked for any water or debris in the bottom, and I wouldnt put power onto the motor untill it has been megger tested, and the whole machine has been connected to a known good earth!! If the motor tests "low" it is not the end of the world, could be just damp, you can connect the windings in series and put a voltage onto it to dry them out.
Phil
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Offline RussellT

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Re: 3 Phase Motor Starters
« Reply #9 on: March 18, 2015, 05:38:46 PM »
Thanks Stuart and Phil.

The starter has been on the lathe since the beginning of time so I'm sure they must be compatible.  I've been thinking about it and I'm fairly sure it can't be a star delta starter as I think there are only three wires out to the motor.  (There were three out to something else which isn't there, possibly a coolant pump - terminating in a box).  I think the lathe is fitted with a clutch - possibly to ease the start up load.

I shall be paying close attention to earthing and checking before I turn it on - and even then I might get its owner to turn it on. :zap:

Lee, I'll try and take some pictures next time I'm there.  It's a big lathe for a home workshop - the taper turning attachment looks like it would make a reasonable bed for a small lathe.

Thanks for the reassurance about PCBs - you've convinced me that they're the least of my worries. :med:

Russell
Common sense is unfortunately not as common as its name suggests.

Offline hermetic

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Re: 3 Phase Motor Starters
« Reply #10 on: March 19, 2015, 02:50:19 PM »
where are you in the UK Russel?
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Offline RussellT

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Re: 3 Phase Motor Starters
« Reply #11 on: March 20, 2015, 09:50:30 AM »
I'm in North Derbyshire, near Manchester, the lathe is in Mellor.

Russell
Common sense is unfortunately not as common as its name suggests.

Offline hermetic

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Re: 3 Phase Motor Starters
« Reply #12 on: March 20, 2015, 11:45:13 AM »
Right, well Im in East Yorkshire (Driffield) so I can't "pop over for ten minutes" Now we know the starter and motor have worked together before, and the starter is a much smaller ones than I have ever worked on, I would have a clean at the top, and see what it says, apart from "made in England" and also the plate at the front, to see if it says DOL (direct on line). As there are only three wires coming from it, we can assume it is, and connect the three wires to the three wires from the motor, the worst it can do is go the wrong way, so make sure the machine is out of gear. If there are any switches or stop buttons on the lathe, you ought to take the tops off and check the condition of the wiring, as these starters came from an era when the wiring was usually VIR (vulcanised india rubber) which is a matt reddybrown colour and is covered with a woven cotton outer sheath. This cable is usually in perfect condition where it is inside a conduit, but tends to dry out at the terminations, with the result that all the insulation falls off! Also it does not like oil, which makes it go all sticky and it can catch fire! If it is VIR I would rewire it in pvc singles to be on the safe side, then megger the whole machine, not just the motor, as vir itself can be "leaky" electrically. With the POWER OFF!! and with the tank off. move the handle on the starter and see if it just moves one position from off to on, check the movement underneath, and check for loose contacts, or anything that looks burnt. The good news is that you can take a fine file to the contacts and restore them to as near to the original shape as possible. WITH THE POWER OFF!!!!! operate the handle and check that all the contacts meet with reasonable pressure as the handle gets to the run position. Filter the oil through the wifes best tights, clean the debris out of the bottom of the tank, refill and give it a try! Some Ellisons have mechanical hold in when in the run position, some have electrical hold in using a coil. With mechanical hold in, the overloads will mechanically trip the stop mechanism, with the electrical system the overloads drop the coil out and the starter switches off, mechanical ones do NOT release on no volts, so beware if you have a power cut, as the starter will stay in the on position and the machine will restart when power is restored!! TBH I am pulling all this from memory, and it is a long time ago, so if you can get a knowledgable "old" sparky on the job, do it! Anyone trained later than the early eighties will run away screaming when they see this equipment!
Phil
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lordedmond

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Re: 3 Phase Motor Starters
« Reply #13 on: March 20, 2015, 12:16:52 PM »
Russell
Like phil I am to far away to pop over Derbyshire Notts border

If the motor has only three wires coming from it it the starter is bound to be a direct online , if it will not hold on in the run position please do not do as I have seen eons ago tie the handle up with string , it was a regular thing to find at Stanton iron works the operator would say the handle will not stay on when I use the machine it turns off so I mended it with some string ( also very common on the local farms except they used binder twine ) , all it was was the overloads tripping , but try and tell them that   :doh:

as Phil has said these were in use pre me and not common after the sixties

Unlike Phil my personal preference was not to file any copper copper contact that had a rolling motion , I found that it cause them to wear out quicker and weld up , but thats my view not to say that Phil is wrong but we were all trained with different mentors and thus have different views

you will have some difficulty in finding the oil if you need some , hope you don't just don't spill it on your shoes or clothes , you will not get rid on the stink , old Murex welders had the same oil in them ( 330 amp jobs ) and I swear they had a green haze over the tank when you craned out the transformer/switch gear they were bad

good luck with it and be safe

Stuart

Offline hermetic

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Re: 3 Phase Motor Starters
« Reply #14 on: March 20, 2015, 12:54:14 PM »
Completely agree stuart! I too have seen the string, mainly on the farm mill motor, which was usually a star delta! On one occasion the stack fork just happened to be the right length. Yes agreed, don't file the roller type contacts, I was meaning the teardrop (roughly) shaped ones that generally burn a flat onto the contact after much use. I really do not know what the contacts on this type are like, the ones I used to work on were on resistance start motors, or big slip ring jobs running things like gravel plant crackers, or huge factory mixing plants. I recognised the modular steel panels with the starters mounted on them, and the steel feet at the bottom though, there was a switchroom in the local Glaxo plant (the UK's first powdered milk plant 1934 in Driffield) that used these with Ellisons bolted to them. My life was saved one day by an Ellison main breaker at Glaxo, which dropped out when I was drilling into the top of a live busbar chamber, and the drill snapped........there was hardly a flash, and I lost a couple of fingerprints as well! I was about 16. (1967 ish) We were converting Glaxo into a turkey processing plant for Twydale turkeys.  It had its own borehole with a beresford submersible pump, a huge gantry crane to pull it out, and a six foot tall starter with glass panels in the front so you could watch it operate (star/delta) 33 years old, still worked perfectly. unlike me!
Phil
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lordedmond

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Re: 3 Phase Motor Starters
« Reply #15 on: March 20, 2015, 01:15:18 PM »
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

Offline RussellT

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Re: 3 Phase Motor Starters
« Reply #16 on: March 20, 2015, 02:43:30 PM »
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.

Anyone trained later than the early eighties will run away screaming when they see this equipment!

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

Russell




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Offline RussellT

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Re: 3 Phase Motor Starters
« Reply #17 on: July 30, 2015, 08:08:05 PM »
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

Common sense is unfortunately not as common as its name suggests.

Offline mexican jon

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Re: 3 Phase Motor Starters
« Reply #18 on: July 31, 2015, 04:39:02 AM »
Nice looking piece of proper machinery that is  :thumbup: :thumbup: :thumbup:
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Offline hermetic

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Re: 3 Phase Motor Starters
« Reply #19 on: August 01, 2015, 04:57:54 PM »
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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Offline RussellT

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Re: 3 Phase Motor Starters
« Reply #20 on: October 21, 2015, 11:57:51 AM »
We finally got the lathe cutting metal this week for the first time since 1991.  Not for very long and the finish wasn't very good but that was probably something to do with the bar being the first bit of scrap we could find and the tool having sat in the toolpost since 1991.

There are still a few bits to sort out, one of the gear levers is loose, the tailstock ram is seized and the belts need tensioning.  There doesn't appear to be any way of telling how much oil there is in the headstock either - although there's a hole in the filler that looks about the right size for a dipstick.  I couldn't work out what the lever on the back of the cross slide dial is for - some sort of stop I think.  It all needs a good clean too.

Next job - the Bridgeport.



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Offline hermetic

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Re: 3 Phase Motor Starters
« Reply #21 on: October 21, 2015, 05:32:23 PM »
Keep at it Russel, and post more pictures! This old electrical equipment can be a bit recalcitrent if it has been stood a while, but used regularly it is reliable as clockwork, and with servicing, lasts forever!
Good luck

Phil.
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Offline RussellT

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Re: 3 Phase Motor Starters
« Reply #22 on: November 06, 2015, 04:52:45 AM »
I had another go this week.  We took the lid off the headstock gearbox and had a look inside - everything was reasonably clean and it's clear that the problem selecting gears is a loose gear lever - unfortunately it's not as simple as tightening the grub screw so further investigation is needed.  I forgot to take the camera so no pictures I'm afraid.

I also had a look at the Bridgeport's wiring.  That was space age compared to the lathe.  The most difficult part of the job was opening up the hole in the box from 3/4 to 20mm for a new cable gland.  I made the connections and it all came to life.  The work lamp needs a new bulb which is clearly a funny voltage - a 240V bulb is very dim.

I'll try and remember the camera next time. :worthless:

Russell
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Offline John Swift

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Re: 3 Phase Motor Starters
« Reply #23 on: November 06, 2015, 07:23:26 AM »
Hi Russel
Lo Vo lamps I've seen used on various lathes had either
2 pin 50V  B22 baynet cap bulb ( like the 240V bulb) or
3 pin 25V B22 baynet cap bulb


you should have the option of selecting 25V or 50V for lighting

 John

Offline RussellT

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Churchill Lathe and Bridgeport Mill
« Reply #24 on: November 10, 2015, 06:50:53 AM »
We had another go at getting the Churchill lathe and Bridgeport mill going properly.

Thanks John for the voltage info. :thumbup:  The multimeter confirmed 48V which I had deduced from your bayonet cap diagrams.

Does anybody know whether modern LED bulbs will run on 48V - they have to have a power supply to convert from 240 to whatever needed for the LED.  Will that also work with 48V?

I remembered to take a camera so here are a couple of photos of the lathe.





The two issues on the lathe are the tailstock ram is seized and one of the gear levers doesn't engage properly.  We took the top off the gearbox to see what was going on.  I thought it might be as simple as a loose gear lever as the lever had a grub screw in the side.  No such luck. :( :(  The outer gear lever was held on with a taper pin, and the inner gear lever was keyed to the shaft - the grub screw was to hold it in position on the shaft.

Here's a couple of pictures of the inside of the headstock.  The input is on the bottom left and output on the top right.  Can you spot the difference?  It will be revealed after the second picture.





The difference is that the dog clutch on the second intermediate shaft (bottom centre of picture) has been moved.  The problem with that is that in the first picture the lever engages with the hole on the face of the headstock and in the second picture the lever is pushed beyond the other hole on the face of the headstock.  Engaging the lever with the hole is not sufficient to engage the clutch.

After poking about for a bit we're not much wiser about what the problem is.  The paint marks suggest that someone has dismantled this before - possibly to try and solve this problem.  It seemed to me that the solution was to move the gear along the shaft toward the bottom of the picture so that the dogs didn't have to move as far - but that would mean it didn't line up properly with the gear on the previous shaft.

Does anyone have any useful suggestions.  At the moment I do have a bodge in mind to stop it jumping out of gear but a proper solution would be nice.

We also had a look at the milling machine.



Even with the help of a diagram we couldn't work out how to disengage the hand wheel to use the quill feed lever.  After much headscratching  :scratch: :scratch: :scratch: :scratch: :scratch: :scratch: :scratch: we realised where the lever was missing from.  Once we'd worked that out it was relatively easy.  Does anyone have the dimensions for that lever?  Most of them are quite easy to measure but it would be helpful to know the distance from the pivot to the centre of the ball.

We couldn't release the high/low speed clutch at the top of the machine.  It seems to be quite well stuck.  Does anyone have any tips for that?

We also started looking at a Pollard drilling machine that needs erecting.  It's very heavy with an 11 inch diameter motor on the top that needs to go between floor joists above.  That job needs more thought.
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