HELP!! Wiring madness

[Nicholas FarrParticipant @nicholasfarr14254]

Hi Les, not sure what you mean, and I’m unaware that I’ve claimed a complete power switching solution, but it does do everything stated in the circuits without fail, and has worked well since I refurbed it.

Regards Nick.

[Robert Atkinson 2Participant @robertatkinson2]

Bevel,

You need to add a contactor like this one:

https://www.ebay.co.uk/itm/183128744561? 2 pole 20A with 240V coil to make your switches work.

Note the blobs I’ve used at junctions for clarity don’t have to be seperate terminals they can be at the component screw terminals. You can put 2 wires per terminal one either side of the screw. So the connection between the E-Stop , Stop and contactor terminal 2 would be 2 wires in the E-stop terminal 12 one going to Stop terminal 11 and one going to contactor terminal 2.

Robert.

[Martin of Wick]

On Martin of Wick Said:

Robert,

I tend to agree with you in respect of connecting neutral rather than live for switching through an EStop, especially if  a whole bunch of additional interlocks are being daisy chained via external circuits.

However, in the case of this single integrated NVR EStop unit, the rest of the world including the manufacturer seem to think that the live should go through the EStop. I genuinely wonder why that is?  Is the risk really significantly higher for a simple integrated switch box?

Who am I to gainsay the manufacturers/suppliers wiring advice? I will try to find the piece of rice paper instruction that came with the unit to post.

I have used one of these simple integrated switch units to replace  the old switch to a .75 kW lathe motor (was assuming the OP in similar circumstance and wanting something simple). You may be amused (or not) to know that the switch replaced was an ancient ornate round brass 1940s style light switch, complete with decaying wiring! So I had rather hoped for a modest reduction in risk, seemingly not it appears.

Hi Martin,
Not sure if we are quite on the same page. I’m refering to the NVR switches the Batxle shows in post 847411 These are not in my opinon an E-Stop. Some (not the ones shown) have an E-Stop latching “mushroom” on a swing down cover. They may be considered an E-stop IF the button forces the contact open regardless of the state of the coil. If an external E-stop is used with one of these it should of course be fitted at the input to the NVR and ideally break both live and neutral (these NVRs are only single phase.) A single pole E-Stop such as Bezel has would still be at the input and break the live. In the units Bayzle shows ther are 4 or 5 connections. The 5th connection “A1” is one side of the holding coil. You can’t tell from the diagram what the other side of the coil goes to because it shows two connections to the “output” side of the switch. This is to allow external interlocks. It is not suitable for an E-Stop as it can’t over-ride a stuck coil. A common failure mode is the coil over-heats (possibly due to shorted turns) and distorts or melts jamming the armature / actuator in the on position. In this failure breaking the A1 connection will not stop the machine. If the interlocks and thus A1 are in the live circuit then they MUST be connected to the output side of the NVR. This is only works because the Start button on the NVR closes the contact without needing to energise the coil. That is another failure mode of these cheap NVRs, the Start button jamming in, possibly due to swarf and you can’t stop the machine.
A seperate contactor and E-Stop is much better.

Robert.

[BazyleParticipant @bazyle]

FYI testing the NVR switch I pictured has the A1 connected to the coil and the other end of the coil connected to pin 4. When the green button is pressed pins 3 and 4 are connected. So you could wire it with pin 3 (which is labelled “in”) connected to live, pin 4 connected to motor input, pin 1 to supply neutral and pin 2 to other motor input. Then the relay coil wire A1 can go through whatever interlocks to neutral or independent earth. This leaves the interlock circuit not live provided you have an earthed neutral (depending on country and wiring protocol).
This seems to be the opposite numbering from the diagram above.

[EmgeeParticipant @emgee]

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