Bandsaw cut out switch wiring

[carbon]

I would assume from the pictures that terminals 'R' to 'W' will be the 3 phase connections and the terminals '1' to '6' will be the low voltage for the control gear. Not sure I like the use of earth cables being used as power connections as it can be a little confusing

 

[scottmk1]

Ok, here's a rough dwg of the whole circuit. The only bit I hadn't labelled is the limit switch.

 

[WorkshopChris]

Are the 2 sets of terminals marked N linked?

 

[scottmk1]

No, the two sets of terminal marked 'N' are on the main rotary switch and the rotary switch for coolant pump, as far as I can remember there was never anything linking them.

 

[WorkshopChris]

Ok rotary switch makes sense now. does the indicator bulb (low Voltage side) light when you turn switch. cant see how the rest of the control side get its power at the moment.

 

[carbon]

If that's the case then only the top panel indicator will illuminate as the lower part of the diagram only has one connection to the low voltage

 

[carbon]

What are the other two panel indicators marked as?

 

[scottmk1]

There's a main power on lamp, main motor running lamp and coolant pump running lamp. The bulbs are all duff so no idea if any will illuminate.

 

[WorkshopChris]

Depends on the bulb holder but some older kit will not operate without a good bulb in as it may be wired in series with the control system.

 

[scottmk1]

I did wonder if the blown bulbs would cause it not to operate, but sort of dismissed that idea as being daft!

 

[rosinante]

Not necessarily daft, I have worked on kit that is disabled if lamp blown. Eg red light on traffic barrier, failed in open position if bulb blown, common call out fault back in the day. The lamp in series with the transformer out put needs replacing or link across terminals to test, have a voltmeter to check for power at the control fuse wrt to earth or neutral
Chris

 

[carbon]

Is the black cable in the picture connected to terminal 96 as this seems to have been added as its not in the trunking

 

[scottmk1]

The black cable is from the limit switch

 

[carbon]

Usually when the overload is not tripped terminals 95 & 96 are NC so I am assuming that the overload is currently tripped if 95 and 98 are connected.
As such I have made a change to the wiring diagram and connected the limit switch to a different location, in this configuration a blown bulb wouldn't affect the operation. But I have been awake since about 4am yesterday morning so it could just blow the fuse on the secondary of the transformer.

 

[scottmk1]

Ok, so is 98 just left disconnected then? I will have a look tomorrow and see if the black cable currently on 98 can be moved to the position shown on your version of the drawing.

 

[carbon]

If the brown and yellow wires are connected to terminals 95 & 96 and if the trip resets and those two connections are NC then there shouldn't need to be a connection on 98.

 

[scottmk1]

Yes the brown and yellow wires are connected to 95 and 96. Another thing that confuses me is that there isnt a neutral from the 3 phase supply, only the 3 phases and earth. Is that right?

 

[carbon]

Yes correct, as you have two three phase motors and a low voltage supply for switching there is no need to have a neutral connection.

 

[Newlands]

I may be wrong here but I think the cable you're referring to on the circuit drawing as neutral or N is actually just a control cable. I hope you or Carbon will correct me if I'm wrong!

 

[carbon]

I may be wrong here but I think the cable you're referring to on the circuit drawing as neutral or N is actually just a control cable. I hope you or Carbon will correct me if I'm wrong!

I believe that the rotary switches have terminals marked with 'N' and are not in this case used to switch a neutral connection, but switch the low voltage for the panel indicators for the mains power and the coolant pump