Lathe Control System

[Barking Mat]

Evening, my lathe is up and running, and all is good,(thanks to everyones previous help), however, and there's always a however, I have a dual speed electric motor, which was originally attached to some 1940's or 50's electrics which have long since been replaced (within the last 25 years ???) by a modernish electrical cabinet with nice push buttons attached to the lathe.

The electrical cabinet is untouched and works fine however when the lathe was moved originally, the cable going to the button box had two or three wires yanked out, these wires controlling the high speed windings on the motor. Photos to come. I have changed alot of the old wires from the control box to the button box and to the motor. No problems here, the problem is I've no idea where these three wires should go. I've had two 'sparkies' pop by become hugely confused and given up.

What works.... I've got the low speed back and fwd, the lube pump on and off, and when I push the 'contactors' for the high speed back and fwd that works, but the latching system is not working as the wires are out and I don't want to risk damaging the system as obviously it's well done and logically it's just the three wires which are needing a home.

Here's what I understand.... from top to bottom, top right: Isolation Switch, top left: fuses, middle left high to low voltage transformer for the control system kicking out 22 volts in my shed. After that we have the four contactors on the bottom, the two on the right which work and the two on the left which just seem to be missing the impulsion to work. The contactor middle middle right is for the lube pump and I think the contactor middle far right is the stop on the latching system.

What I don't understand...... these contactors are electromagnets which when powered up make a switch close to power the motor.... are these contactors fired on low voltage or 400v? I remember at school very vaguely latching circuits but it's all well vague. Is there as such latching circuits involved or do these clever contactors do it all???? I don't know.
I would be nice to have my little console of buttons working, BUT I have come up with another solution if it's just too complicated to fix, I was thinking I could just bolt a female 3ph socket to my control box and when needing to swap between high and low I could just plug the relevant windings in. This is one solution however it would be nice to have it 'all' working.

I have a pretty good understanding of electrics and chasing things round fuseboxs with my multimeter, but this has got me, and with it plugged in I'm getting so confused by not really being able to understand how it works. So I'm throwing this open if anyone has any constructive ideas fire away, and I've tried following all the wires some of which are numbered but with no success. Anyway here's some photos.

Thanks in advance, yo ho ho.

 

[penfold]

Where are the wires dislodged from?

 

[Barking Mat]

The wires were dislodged from the button box attached to the lathe, if it helps I'll take a photo of the insides of the box, but seeing as the wires aren't attached I couldn't see the point. I would imagine these 'contactors' are fairly universal and not just some French invention. As you look at the button box it's the top left and the one below it.

 

[madkayaker]

The hold on contact is possibly on the top contact with interlock going through the other pair

 

[Barking Mat]

Mad kayaker, please could you expand on this....

 

[Barking Mat]

Surely ???? There's no flip flops or bistable multivibrators???? It's the contactors ?????

 

[Barking Mat]

The stop switch is shared for the four speeds if that's what you mean?

 

[madkayaker]

The orange block on top of the contractor has two sets of contacts and I bet one is normally open other normally closed. The open contact is Parallel across the start button so that once closed power continues to flow to A1/ A2 (coil) the other contact is normally closed and the alternative function is wired through this so that forward and reverse can't be used at the same time.

 

[Robotstar5]

The orange block on top of the contractor has two sets of contacts and I bet one is normally open other normally closed.

53 - 54 are normally open and 61 - 62 are normally closed

conventionally contacts numbered n1/n2 are N/C and n3/n4 are N/O

 

[madkayaker]

53 - 54 are normally open and 61 - 62 are normally closed

conventionally contacts numbered n1/n2 are N/C and n3/n4 are N/O

Couldn't remember which way round it was

 

[Barking Mat]

Thanks folks I'll go attack that imminently.

 

[Barking Mat]

Yes, madkayaker and robotstar5, continuity between 53 and 54 until pressed and 61 and 62 continuity when pressed. So when the coil is energised by a button stroke 61 and 62 hold it latched. Am I correct in thinking this little thing is just switches? and where does the impulse to the coil / electromagnet come from?? Where is the coil / electromagnet? Thanks again.

 

[Barking Mat]

The three wires not connected in the button box are 2,7 and 8.
7 and 8 are both linked to terminal 53 on the far left and left contactor, which is normally open. Wire number 2 is attached to the block below the isolation switch far right at the top below the isolation switch.
However, there is continuity on each block between 53, 61 and 62, 61 and 62 being normally closed, which is where I start getting confused.

 

[Barking Mat]

Yes, some success, wires 7 and 8 sure enough are the commands for the buttons, but adrift wire no. 2 does not actuate them. I found that taking a feed from the slow speed buttons allows the actuation of the fast speeds on the motor. BUT.... I can now have for example the slow speed and the fast speed on at the same time. Wire no' 2 seems to fire the contactor which is STOP? up on the top right hand side under the isolation switch which I have never seen work before. I assume if you already have one speed running and try to use another speed it's their to cut out?????
I think I've solved one problem by joining the slow supply to the fast, so at least it works, but I may have just created another problem?
THANK YOU KIND FOLKS FOR YOUR HELP.

 

[Pete.]

There's no way they should both close together. Power for the pull-in coil of one will pass through the NC contacts of the other, and vice-versa, to form an interlock. If one contactor is pressed the other cannot then have power.

 

[Barking Mat]

Thanks Pete, I suspected this was not right. I've simply put a jumper from the side which works to the side which doesn't work. So I'll try to establish where the feed should come in. (at least a couple of wires identified). And then the wire adrift which fires another conatctor I'll just ignore for the moment. Unless this is an emergency stop??? Thanks.

 

[madkayaker]

the feed for the hold on contact will be on one side of the push button. all the hold on contact does is connect accross the push button

 

[Barking Mat]

OK, I'm getting somewhere... The two contactors on the right which work have both 26 volts running through the 53 and 54, whereas on the left I've only got 10 volts. I've tightened numerous contacts but it doesn't seem to be a loose wire, and I'm not having much luck figuring where this is supplied from, although it's obviously from the step down transformer. And i'm assuming it's not the contactors as earlier when I jumped them they all worked, so it's hunt the drop in voltage.

 

[madkayaker]

it would be very easy for me to how (and harder to tell) turn all the power off and check for continuity between 53 and 3? on the start button and again between 54 and 4 of the start button that should prove the hold on part. then check between 54 and A1 on the alternative function contractor

 

[Barking Mat]

I think a three position toggle switch will be used, the middle position being stop and therefore, logically there's no way anything can go wrong. Thanks for your help folks.