Single Phase Switch + EStop?

All, while I'm messing about with the ML7, I was looking at the on/off button I fitted to the machine when I got it - previously it just had a plug on the motor wire.

It's a single phase Hoover motor, which works OK, usual three core cable going to and from it - I also replaced that when I got the machine.

Can anyone recommend a replacement ON/OFF switch with an EStop button? I was thinking it might be a good idea while I'm messing about with the mechanical bits.

Also, are there any other electrical safety items I could/should fit - RCD or something like that?

Thanks.

IF the Hoover motor is open to the entry of brass 'chips' etc , you would do well to place something in the path to prevent that happening BUT do not hinder ventilation/cooling of the motor.

You mean something like this?

ML7 Hoover Motor Cover | Model Engineer (model-engineer.co.uk)

This sort of thing maybe?

**LINK**

If the mains goes off the switch is released so the machine doesn't come back on when it's restored. They are also available I think with a hinged cover with a big mushroom estop actuator that operates the stop button and that you have to lift to reach the start button.

I've used RS part 398-5279 . It is a panel mount NVR switch.

It has a connection for a second external E-Stop button - if this connection 'sees' a closed circuit then the NVR power can be switched on. If anything (like an E-Stop switch) breaks that circuit then the NVR switch will trip to off. You could (should you wish) wire multiple E-Stops in series on this cricuit and then any one of them would trip the NVR off.

Being panel mounted, you need to make sure there is no access to the gubbins at the back - including the E-stop circuit which also carries mains voltage.

I had been looking for one for the Atlas 12 x 24 which is being refurbished. It has the box included. This does not have reversing capability.

**LINK**

Edited By old mart on 02/03/2021 14:52:48

If a No Volt Release Switch is fitted between the plug and the machine, the red "Stop" button will act as an E Stop.

If the supply is interrupted, the switch drops out until it is reset by pressing then green button.

The reversing switch should only be operated (especially if a Dewhurst type), when the motor is stationary.

Howard

Dr.

I agree that the stop/start switch linked to by Old Mart will be suitable to provide no-volt release protection for the supply to your lathe and is best fitted within easy reach when operating the lathe.

You may wish to consider fitting a DOL (Direct on Line) starter complete with an overload rated to provide overload protection to your motor, the overload tripping range needs to suit the motor FLC on the motor plate.

If it is not possible to fit the starter so the operating buttons are easily accessable when using the lathe remote start/stop/emergency buttons can be wired into the starter control circuit.
This would cost more than the NVR protection switch but would provide NVR and overload protection.

As we have no knowledge of your existing electrical supply and distribution method it is difficult to advise on fitting additional safety units but I would advise all 13A socket outlets have RCCB protection rated at 30ma tripping current, especially for hand held earthed equipment and electrical equipment operated outside.

I am not certain but I believe to comply with current electrical regulations it is now mandatory to provide RCCB (Residual current circuit breaker) protection to all circuits.

If this is the case it can be achieved by the use of a suitably rated RCCB supplying all final circuit protective devices fitted in the distribution board, power to the RCCB direct from the main switch.
The problem with this arrangement is if one circuit has a fault the power is lost to all circuits.

It is usual now to fit RCBO devices which provided overcurrent and balanced load protection to individual circuits.

Emgee

Ok thanks all. I'm no electrician, so I'll have to wade through some research to figure all that out.

In terms of the RCCB question - the house was built in 2004, not sure whether that means all circuits are protected or not.

All the machinery in my workshop is powered through a latched RCD socket. If the power goes off the socket unlatches and needs resetting when power is restored. Additionally the bandsaw and belt sander have built in NVR switches and the VFDs also require switching off and on again if the power to them is interrupted.

The only equipment I have left on and had start as soon as the RCD is reset is the compressor and that, whilst reasonably safe, does make me jump if I'm not expecting it.

Martin C

I think the SX2P latches off in the event of power being cut. The lathe doesn't.

For the Mill and Lathe, I have a long, six switched socket extension cable, that plugs into a normal 13A socket on my bench. The cable is routed up to the cieling, then over and down the the island where I have the machines.

I suppose I could just plug an RCD into that supply socket to protect both machines?

It would be best if it was a latching RCD that has to be reset if there is an interruption to the power, I don't know if they all work like that but do know that some do.

Martin C

This is the box for the house:

If all else fails, insert a plug-in RCD into the 13A socket and the plug for the lathe into that.

If the mains drops out, the RCD goes open circuit and has to be reset manually when power is again available

My ring main in the shop is fed by that means..

It does not provide an emergency stop for machines, but in the event of a leakage problem does provide protection.

Since my shop has no windows, there is also a safety lamp with battery back up, to provide light if the mains supply is disrupted, allowing illumination for a safe exit.

Howard

Thanks Howard. I guess the Estop switch for the lathe isn’t a bad idea in addition?

For many years every new machine has been equipped with an Emergency Stop switch which latches down, and has to be be released mechanically. TWICE I have wasted an afternoon, fault finding before spotting that the Stop had inadvertently been depressed!.

So, almost every hobby machine supplier should be able to sell you an Emergency Stop switch. It may need to installed in a enclosure to keep itself and the operator safe, from swarf or electrocution.

On a mini lathe and on the RF25 Mill it is merely a cover which latches closed, to hold it down, when the Stop is pressed..

On the Mill it is a feature of the NVR switch. Without investigating the circuit diagram, am unsure about the Sieg mini lathe (No doubt Ketan can tell us )The generic 4 1/2" bandsaw only has a NVR switch.

Howard

Hi

i have fitted these NVRs in the past from Warco

https://www.warco.co.uk/accessories/346-nvr-switch.html

I have fitted them to bench grinders too.

Paul

Dr-GMJN

Your distribution board is a split unit, all final ccts isolated from a main switch on the left, if the workshop supply is taken from one of these 6 it will not be RCCB protected.
See there are 2 Merlin Gerin mcb's fitted, perhaps they are exclusive types not available from the other manufacturer.

Next is the RCCB unit protecting the 6 final ccts to the right hand side, the last one labelled Outhouse.

The picture is not good enough to see the labelling to other mcb's but if your workshop is supplied from 1 of the mcb's to the right of the RCCB it will be protected by the device, the rated tripping current will be printed on the front of the unit, I would think that will be 30ma (030)

The Electrical Installation Test Report (or Periodic) will provide details of the RCCB rated operating current and time taken to operate in the event of a fault at Rated and 5xRated current.

Emgee

Edited By Emgee on 03/03/2021 16:07:23

Thanks everyone - all workshop sockets are on the second switch along from the far right of the box.