Bandsaw cut out switch wiring

[scottmk1]

I have almost finished sprucing up a Fendo 250M bandsaw, and I need to re connect the two wires that go to the cut out switch to stop the blade when the saw has finished its cut. When I stripped it I marked all the wiring as to where it goes but for whatever reason, forgot about the switch wiring.

I have no manual or wiring diagrams for it & so far Fendo havent been very forthcoming when asked for a manual etc.

Any ideas where a switch like this would normally be connected?

 

[rtbcomp]

Assuming the switch opens at the end of the cut and if the saw has a contactor I would wire it in series with the contactor coil, otherwise in series with the motor.

 

[scottmk1]

Thanks, it's a 3 phase machine so I'd say it has to go in series with the contactor coil?

 

[rtbcomp]

^^ Yes - it's unlikely to be 3 pole!

 

[scottmk1]

Ok, had a look but cant see any spare terminals on the contactor. There's a spare terminal on the thermal trip? and another on the terminal rail. The wire on the terminal rail that has the spare goes up to the emergency stop, would it make sense for it to connect there? Can upload some pics of the wiring if it's of any use?

 

[rtbcomp]

Pics would be good there's sure to be someone on here who recognises the type of contactor. It could be in the emergency stop circuit, all that does is drop the contactor out.

 

[scottmk1]

Ok Here are some pics.

I can make the main motor run by manually pushing the contactor in, and the coolant pump also runs if switched on & the contactor is manually operated.

 

[rtbcomp]

That looks overly complicated! Hopefully an expert will be along soon.

 

[scottmk1]

Ha! Yes that's my thoughts too.

 

[brightspark]

its a difficult one just seeing a picture . but be reasonably easy to test and work on it live with a test meter

 

[rtbcomp]

That's what's so frustrating about this sort of problem - having the thing in front of you is one thing, having something you've never seen before 200 miles away is another!

 

[scottmk1]

Aye, whats even more frustrating is that I labelled all other wires, but not these two

 

[rosinante]

I think that a cut out switch will be in the contactor coil circuit, the wires will be in series with the stop circuit wiring removing power from the contactor coil , if you google direct on line starter circuits you will see, it doesn't matter if single or three phase as retaining, stop cct are same principal, the emergency stop circuit is the most likely ,connect the cut out in series and try it, a simple test meter checking continuity would be a valuable and cheap addition to your tool kit,
hth
Chris

 

[rtbcomp]

"I can make the main motor run by manually pushing the contactor in, and the coolant pump also runs if switched on & the contactor is manually operated."

Does it work from the start button?

The presence of a transformer suggests that the contactor coil & associated circuits may work off a low voltage. The label on the contactor should confirm this.

 

[scottmk1]

No it wont work off the start button, if I have the main switch on I can hear the transformer power up and pushing the start button for the main motor does nothing. The coolant pump has a rotary on/off switch and does nothing when I switch it on however if I have the main switch on and manually operate the contactor the main motor will run and if the coolant pump is switched on that will also run.

I'm nipping down to Cromwell shortly to get new leads for my meter shortly as one of mine seems to have a broken wire inside, which is giving me bad readings and isnt helping matters.

 

[Newlands]

There are some generic wiring diagrams for dol starters here http://www.schneider-electric.co.uk/en/faqs/FA139744/
Assuming that you contactor has the conventional numbering for the terminals, cut-out switches are usually wired in the link between terminals 14 and 95, or more usually * between A2 and 96. Two switches can be wired in series, eg one on a guard and another on a door. In normal operation these would be normally closed (NC).
Maybe the reason your motor will only run when you manually push the start button is because you haven't connected the switch up in one of the links yet.

* I have no idea why this is the link normally used for the e-stops and safety switches rather than the 14-95 link!

If your contactor uses a different numbering convention for the terminals you may struggle, but maybe the diagrams will give you a bit of a clue, as the principles should be the same. Hope that helps.

 

[scottmk1]

Hi Newlands, thanks for that. Yes I think I have missed a connection somewhere to complete the circuit hence the coil will not energise & close the contactor. I may well get a spark in to have a look now as the more I look the more confused I get. Looks like someone has rewired part of it too.

 

[rosinante]

If it is just the control circuit that is incomplete it shold be easy enough to physically follow the wires around the machine , draw a line on a bit of paper, put a dot to represent the contactor coil terminal , follow the wire to next terminal and mark on line , pursue this idea until you come to a switch mark that etc , obviously one route will take you to the control transformer probably via a fuse, just proceed logically, the only thing in paralell with be the retaining circuit contact which is normally an auxiliary contact on the main contactor, a stop switch regardless of how it is operated will interrupt the supply to the main contactor coil causing it to drop out, an emergency stop switch will have a latching facility which will require physical reset ,Idoubt it will be any more complicated than that,
Hth
Chris

 

[Sidewinder]

The stop switch will be in series with the e-stop/stop button, hence why the machine won't start from the start button, but runs from depressing the contactor armature.
I would also expect the thermal trip to be in series with the e-stop.
Where does the wire on the terminal rail with no connection go?

 

[scottmk1]

Thanks again for the replies guys. I've been out and traced the entire wiring out so will draw it up neater and post it here.