Installing Nvr Switch With E-Stop - Problem!

Hello all;.

This is my first post on the forum, so here goes!

I have a small single phase Myford lathe which works fine when hooked up directly to the mains via the manufacturers Live / Neutral terminal block at the rear. It also has a simple inbuilt on / off switch. Since there is almost zero inbuilt safety here, insofar as if the current was interrupted and the on / off switch was not returned to 'off' before the supply was restored, the machine would start unexpectedly.

So, I decided to install an NVR switch with an E-stop, with the intention of taking the output to the existing terminal block.

Now the machine will not work at all!

Reverting back to the original arrangement, everything is fine, so obviously I am not wiring up the new switch incorrectly somehow. I have bypassed each component to determine if any are faulty, but no success.

 Enclosed is a photo of the new switch arrangement.

Can someone please explain how I wire this up to the point at which the supply enter the terminal block of the lathe?

If any more information or photos are necessary just let me know!

Cheers - Nick.

NVR switch with Emergency stop.pdf

I'm afraid that picture doesn't help much...

Could you post a pic of the back?

is this lathe for personal use or business / commercial?

did the switch not come with instructions / wiring diagram?

Ok, I could open the Pic.

Make sure that there is a link from the stop button to the start button. Also your incoming line goes to the stop switch (Normally closed) and the outgoing to the lathe comes from the start button.

Another pic would be really helpful. Even a diagram of how you have wired it

Rich

I'm having trouble uploading a photo of the rear of the switch.

But to clarify on how I wired it:

Incoming from mains into E-stop terminal 1 & 3. Output from E-stop to terminals 13 (live) and 23 (neutral) then from terminals 14 (live) and 24 (neutral) to terminal block on lathe.

The lathe is just for my personal (hobby) use. Unfortunately, no diagram with switch........

New picture?

need a photo of the back really

Here's a picture of the rear of the switch box.

NVR switch with my wiring arrangement.pdf

Looks like the wrong sort of switch to me.... made in china crap...

Why not buy a proper motor starter or make one with a contactor??

One very important thing you have missing is overload protection for the motor, do it properly and you will have an overload relay to go with your contactor..

john..

OK, it's wired wrong from what I can see.

I can't believe that it came without instructions!

Next, an E-Stop is not normally a 2 pole device, it would appear from the pics that you have a normally open and a normally closed contact on the e-stop.

The first thing you need to establish is if this is so.

Also forget about switching the N, just connect it directly to the motor, you will also need to connect one other terminal to the N as well, but you need to identify that first.

Once you have established if you have NO & NC on the e-stop, then you need to look at the NVR switch.

I don't think that those are the only connections on it, it should have a1 & a2 terminals.

Terminal numbering follows a defined sequence from the ISO/IEC standards.

1/2 are the first pair of NC 21/22 are the second pr, 31/32 the 3rd etc.

3/4 are the first pair of NO, 23/24 the 2nd pr, 33/34 the 3rd etc.

a1 & a2 are the terminal markings for the coil device on a contactor.

It does not look very well made, and as App87 has said, you really should have overload protection on the motor.

Snake - great feedback - thanks.

I can comment as follows:

E-stop has 1 NC (terminals 1 -> 2) &1 NO (terminals 3 -> 4) arrangement.

As far as the NVR is concerned, I believe that it has an internal link (A1 -> 24) already in place, which is why only 4 terminals are presented for connection.

Hope this helps to clarify the eventual solution..... 

OK forget the NO terminals then, even remove them from the switch.

You are going to have to identify which is the a2 then.

The e-stop should not interrupt the power to the motor, it should interrupt the power to the nvr switch (contactor) coil.

Is there a specific function for A2?

A1 and A2 are either end of the solenoid coil that holds the contactor closed, or "on" if you like. A contactor has various terminals, the main ones for switching the load [your motor] and a pair of NO auxiliary ones 13 and 14. In the simplest way of doing things, these are wired in parallel to your push button "ON" switch.

You press the button and power is supplied to the coil, this closes the auxiliary switch, so that even when you take your finger off the button, the contactor stays closed, it has "latched" [as the auxiliary switch has bypassed the ON button]

The off button a [NC type], goes in the feed to the ON button, it is in series with the ON. As soon as you jab this, the feed to the coil is interrupted, and the contactor opens. Now, imagine there is a power cut. Coil is de-energised, and the contactor opens. When the power comes back on, nothing happens, as the switch 13/14 has popped open too, and is still open...

As to where A1 and A2 are connected, depends on the coil voltage and what you are doing..

You have found the coil A1. Now try to find which other terminal is connected to the other end of the coil and you should be on to a winner soon!

As Sidewinder said, the E stop should also be in the feed to the coil, NOT the feed to the motor. The E stop switches off the contactor, NOT the motor directly if you follow me...

john...

All you needed was a contactor wired up using the original switch on the lathe... Would have been cheaper and far better too..

Hello to everyone who helped me on this!

I have now successfully wired in the switch assembly as follows:

• Live incoming to terminal 2 of E-switch then out from terminal 1 of E-switch to terminal 23 of on/off switch. Output from terminal 24 of on/off switch to terminal block on back of lathe.
• Neutral incoming to terminal 13 of on/off switch then from terminal 14 of on/off switch to terminal block on back of lathe.

Works perfectly! :signthankspin:

Cheers - Nick.

You could end up overloading the e-stop button contacts, depending on the current your motor is drawing as you are feeding motor current through the e-stop contact, that is not the way it should be done and is not good for the button, nor is it good and safe design.

The e-stop should only operate on the nvr switch, it should not carry & interrupt motor current directly to be honest.

If you overload it the contacts can fail in the closed position and when you need the e-stop it won't work.

Works perfectly does not equate to safe!!

john...

It's ok chaps he'll replace the parts as they fail to Maintain the safe system.