Boxford lathe electical fault

Hi everyone I have a Boxford gearhead lathe a STS10-20. This is a 3 phase machine running off a Transwave converter. Well last night I went to start it
for the first time in two weeks and big problems. main switch on lathe on OK but pressing the start button I had a buzzing noise and then after 10 sec or so it just stopped. Opening the lid and a smell of hot electric's and the transformer warm to touch. All fuses are OK, plug and the two mounted on the transformer.Qustion is where do I go from here. I take it my tranformer is cooked and will need fixing or replaceing, However I know very little about electical stuff just half rememberd stuff from rewiring motorbikes 20 years ago.Any advice or help will be very welcome. I have been saving my pennies to spend at the Harrogate show and now my lathe is Kautpu.
Very Pissed Off Mike
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Mike cole wrote:

I thought Transwave converters are based on phase shifting using Capacitors?
Rob.
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Mike cole wrote:

There are a number of things it could be. 1 some capacitors have failed in the converter 2 the voltage controlled relay** that switches in the starting capacitors. 3 The transformer 'might' be cooked but not very likely unless it had been overheating in the past. Your experience of motorbike wiring will not help you work on the converter. There are lethally high voltages (400-500v) inside.
Transwave are pretty helpful but they are not likely to be able to diagnose on the phone. Your best bet will be a electrically competent mate who knows about converters (not everyone does!!) and can come and have a look.
** If your converter has a manual 'Boost' button, then it possibly won't have a voltage controlled relay.
Whereabouts are you? and which model converter do you have?
If you are not too far away - maybe I could have a look for you.
Bob
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Bob Minchin wrote:

Actually i'm in mid wales, i'll have a look if you're too far away from Bob.
Rob.
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wrote:

The converter is fine, but it's the electrics in the lathe that have have the problem. I know that the voltages are very much higher then my 12vbikes and not to be taken lightly. Thanks for any offers of help, I live on the wirral, so mid wales might be a bit far to pop over. Thanks Mike
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Mike wrote:

Yeah fraid it would rather. So it's nothing to do with the converter? What are the bits in the lathe that are complaining?
Rob.
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Mike wrote:

Hi Mike,
So what is this transformer you said was warm??? Did you mean the solenoid in the no volt release switch/motor overload protection unit? The solenoid buzzing can sometimes be a bit of dirt/swarf that is stopping the solenoid armature seating fully when the power is switched on. Maybe the buzzing was coming from your motor and there is a fault in that causing the overload protection to kick in - that would be consistent with the 10sec or so time delay.
Or maybe a combination of the two? Dirty solenoid leading to only two phases connected and then overload?
I'm in Southampton so a bit too far to pop in.
However a motor starter switch problem needs less know how to sort out than a converter so maybe a more local reader can help??
Good luck
Bob
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I well get back into the shed tonight and have a calm look at what's what. The transformer or what I have been calling the transformer is quite small about 2.5 inchs sq.
Mike
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Mike wrote:

Perhaps you take some photos of the offending part.
Can you repeat the Start- buzz- 10sec delay then switch off cycle tonight or has something stopped working?
Bob
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Hopefull this is a link to some photos
http://community.webshots.com/user/mcole15
I am not getting anything on the lathe, no power light no buzzing
Mike
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Hi Mike, I've got an STS 1020 single phase, but the contactors in the control box are all 3 ph, but wired for single. The transformer you refer to is the control voltage txmr and provides 110V on my STS and I suspect the same for your machine, to the contactors and relays. Power is applied to this transformer as soon as the red knob main breaker on the top front lhs of panel is switched on. On my machine the neon indicator on the front panel runs directly off the 110V so this should indicate the presence of 110Vif it's on. It's possible that this transformer has just failed or a contactor has shorted causing it to fail, but it shouldn't run hot. Mike
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On Apr 30, 10:29pm, snipped-for-privacy@micomsystems.co.uk wrote:

I think you are right here. I do not get 110v out but I am getting 390v on the other side. I can get the motor to run by holding in one of the reset buttons. So the fault appears to be in the control voltage txmr(whatever this stands for). Away for the weekend so will not be able to look more closely till Tuesday. Are these control voltage txmr fixable? Thanks for the advice.
Mike
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Mike wrote: So the fault appears to be in the control voltage

Transformer?
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Mike wrote:

Mike,
looking at your photos there is indeed a transformer in there. These are not repairable unless there is a fuse that needs replacing. The trick is to find one that will be electrically AND mechanically suitable. Boxford can not doubt supply the correct part at a price but there will be others around. You should also try to find out why it failed as it is pretty rare(but not impossible) for a transformer to just die.
You need one that takes in 415/440 volts and delivers 110 volts. I would imagine 25 VA(bit like watts) will be adequate - maybe the other Mike can confirm what else it has to power?
Bob
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Bob Minchin wrote:

Would this one fit in the box?? http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&RB46159
Bob
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Bob Minchin wrote:

http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&RB46159

Or this one? http://cpc.farnell.com/imo/mtsnp100415110/transformer-control-110v-100va/dp/FF01472
Bob
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Hi Mike, There is a fuse for the 110V mounted on the transformer(txmr). There is also a fuse for the 12V light circuit(if fitted) next to it. The 110V is the upper one with the panel open. The 390V you measured on the other side of the transformer is the input to the transformer from your 3Ph supply. If as you say in your first post there was a buzzing when started, I would suspect a fault in the contactor. First check the 110V fuse and confirm if the transformer is kaput.
Mike
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replying to mike, Tony Burdett wrote:

Hello ,I was interested in your post re single phase STS Boxford. I have just bought an STS 3 phase and would like to fit a 1ph motor, do you think it possible that I could use any of the switches already fitted , do you have any wiring diagrams of the single phase set up .Regards Tony . snipped-for-privacy@btinternet.com
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