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Y start Delta run starter wiring

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Plastic
Joined
Aug 25, 2021
Im hoping someone here is savvy with old machine starters. I picked up this old 1986 Supermax Engine Lathe LG-1440 at an auction. It was kind of a rough ride getting it back to my shop so Im not surprised something is wrong. I have some experience with old machine wiring but never seen this before and its got me confused. Its got a Y start (wye start, star start)delta run configuration. If im understanding correctly then of the 3 magnetic contactors the left one is the main contactor, middle is the delta run, and the right one is the Y start? Whats happening is when I push the on button the middle contactor engages and it turns on but wont hold on. Shouldnt the right one be the first one to engage? Also kind of strange, when if I hit the main contactor manually it will spin in reverse. I used a meter and am getting full voltage on all 3 legs and All the E stops are working. Any ideas? Also if anyone knows where to find any manuals or wiring diagrams for it that would be a big help.
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if it is running backwards, reverse two of your legs. Also if on a convertor, don't use the generated leg on the control circuit.
 
Looking at the wiring, I dont think that is a star/delta starter. The main contactor on the left is one direction and the centre contactor swops the phase rotation ,so that would be a reverse. The wiring on the contactor on the right will be to do with the e stop and no volt release. Possiblt the coolant pump, cant really tell from the photos.
As no704 said,try swapping 2 of your phases over to see if you have the control circuit on a generated leg. If the small contactor on the right is not closing when you have power on you will need to check the control circuit as there may be a problem with a stuck e stop or a saftey switch not working correctly.
Have you checked the small fuse next to the large 3 fuses?
 
Thanks for the quick reply. There is a coolant pump on the back but the magnets dont control that. It operates by a different button on the front and seems to be working fine. If I manually push them one at a time this is what happens-
left - reverse spindle rotation
middle - forward rotation
right - forward rotation
I checked all the fuses and e stops and are working correctly.
As to your other comments Im a little unfamiliar with the terminology. By "generated leg" do you just mean a hot leg? and how can I tell which is the control circuit?
 
The control circuit is the start/stop for the machine, this will be the forward /reverse switch and any interlocks (such as gear cover switch) and your e stop switch. Because it is awkward/impractical to have these switches take full motor power they use lower voltage to control the switching.
There is a transformer (the big red bit) which lowers your incoming voltage for this. The small fuse to the left of the transformer needs checking to power the circuit.
When you push the right hand contactor in the machine runs? If so, can you please check if the middle contactor closes when you do this? If it does, I would be looking at the control wiring for a faulty switch.
By generated leg, are you on a phase converter or grid 3 phase? On some phase converter setups ,only 2 of the phases are live until the motor starts and if the control circuit is powered off that the machine may not start.
 
ok, so I checked all the e stops, switches, and fuses and they all seem to be working. Our grid has 3 phase and Im getting appropriate voltage on all 3 legs. I swapping the legs around and it didnt make any difference. When I push the right contactor it does run tho it doesnt sound great, noise coming from the contactor, but the middle contactor is unaffected. Are they both supposed to close together? I do see what your saying about it looking like it has a reverse switch based on the contactors but there is no reverse switch on the machine. Plus the motor cover plate (pictured) does show wiring for a Y start Delta run configuration. Still cant figure it out...
 
We have quite a few European blower motors that are wired that way.So his dosn't have a reversing contactor,it needs both contactors,one to start on y and one to shift to delta on the other. The purpose is for a reduced currant start, a "soft start". Don't know why a small lathe would need that.
 
The machine will have a reverse, just on the right of the apron is the power lever,normally up for forward,centre off and down for reverse. Check it is in the centre before trying to start as the lathe has no volt release on it and will not start if you apply power to it in the run position.
Could you please take a pic of the transformer (big red thing) in the cabinet showing which terminals are connected? I had a thought if the machine is set up for 480v and you are on 240v 3 phase,
The motor plate is showing how to wire the motor for star/delta starting, but if there is only 3 phase wires going down the conduit to the motor then it isn't wired for it.
I'm trying to find a wiring diagram fr your machine and I'll post it up if I can find one.
 
Does your lathe has a clutch I only have seen Y-Delta on lathes with a clutch
It seems to me also this is a forward and a reverse contactor (The left and middle one ) The right one is a auxilary contactor then
If the machine keeps running backwards if you switched 2 leads in your plug the motor sees 2 phase only That way the motor turns randomly and sounds bad
If you engage the contactors manualy by pushing on it with a srewdriver does the motor run different directions and does the motor sound bad in both directions ???
Get a ohmmeter and check the wiring

Peter
 
as oilyniel said, your motor is capable of running delta or Y, but your control is not set up for it. Since you have a 12 wire motor, you would need all 12 wires coming into the cabinet.
 
These use fairly standard wiring configurations, the first two contactors are the forward and reverse, you can see this because it just flips two of the motor power wires to the motor, there is also a NC terminal interlock so both contactors cannot operate at the same time. The third contactor is the power interlock, so there is often a main momentary power on button that latches this closed and would drop out if power is lost (i.e. requires the button to be pressed when power comes back on). If the motor runs the wrong direction, you could also switch two wires on the power coming in .It is possible that a contactor or motor overload relay has failed if the contactor does not click and stay on when operating the spindle switch. You should be able to check the voltage going to the contactor coils in a step wise fashion to see what is failing. Red wires are the control power, black are motor power. Maybe different given the motor cover wiring, did not see that, but the contactor wiring looks more traditional wiring and you only have 3 power wires going to the motor.
 
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These are a good wiring diagram which should be pretty close to your machine, its for a 1440 lathe.
You need to check the output from the transformer to check you are getting the correct voltage and then trace through to find where you lose continuity.
 
ok your right, that is a reverse switch not a Y-Delta. Ive attached a pic of the transformer and checked the voltage on it and here is what Im getting at each leg
R-130v S-130v (230v between the two)
X3-150v X1-60v
This doesnt really make sence to me based on whats labeled on it but it does seem its wired 230 (correct me if im wrong)
Also i should mention it is on a circuit rated for much higher amperage (this is just temporary till we find it a permanent home here). I didnt think that would make a difference but just in case thought Id mention it.
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I checked the right contactor and these are the voltages Im getting at each leg
10-40v 9-40v 8-150v aux-60v
this seems odd to me but im still not sure what this one is used for.
 
Thanks for the wiring diagram, I still cant find anything on this machine which i find very odd. I do see the fwd/rev lever and pulled the switches out and they seem to be working (checked with an ohm meter) but still unable to get it to stay on. Those switches go into the right contactor and do have an affect if pressed when i manually activate that contact. The voltages seem odd on that one (posted above) could it be that one is bad? Where do you guys get new ones if needed?
And so if Im understanding what should be happening is the the lever is switched to either fwd or rev and the right contactor activates AS WELL AS one of the other two? So would that mean im not getting enough power to the right contact?
 
Look at the coil voltages, vs the tap on the transformer.

Also look for any safety switches that could be blocking voltage from the coils of the contactors. And the overcurrent on the left contactor.
 








 
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