NVR switch question

[dzarek1410]

Hello
I have a small workshop and recently added lean-to extension where planned move dust extractor.
I would like to switch it on and off from workshop rather than go to the extension each time I want to use it. Can anyone advise how to "extend" NVR switch?
Thanks in advance

 

[CHJ]

If it's in a normally closed extension outside the workshop then it may well be OK to operate without the NVR, so it can be bypassed and fed from a normal switch within the shed.
Just make sure the extractor power feed is such that the machine has to be unplugged before any cleaning and servicing.

My extractor for instance has a short lead (300mm or so) plugged into a remote socket in its housing fed from a switched socket by the lathe such that it has to be unplugged before it can be accessed for cleaning or unblocking the impellor etc.

 

[deema]

Never, ever have any machine without a NVR. At a guess the extractor will have some form of over current protection built into the motor, most small machines do, so look at the motor rating, say 1KW and toddle off to say Screwfix and buy a standard motor starter for that power rating. They don’t come with a an over current trip and cost c£25. I would wire in some form of visual signal that the extractor is on such as a light to remaind you to switch it off. When my workshop was in the garage and the extractor in a lean to, I used a coloured light bulb. Amazing how often it acted as a visual que to switch off the extractor!

 

[Sideways]

If the nvr switch is in its own box, and you have a separate terminal box physically mounted on the motor, you can replace the cable between them with a longer one and move the NVR switch box somewhere inside your workshop.
You should use a decent flexible cable of the right rating and when you route it, allow some slack so that vibration and movement of the extractor doesn't stress the cable. Make sure the cable glands seal properly on the sheath of the cable at both ends to maintain the machine's electrical safety and dust resistance ratings. If you take this route, you may well need to fit the right types of new crimp connectors at each end of your new cable.

 

[user22161]

Never, ever have any machine without a NVR. At a guess the extractor will have some form of over current protection built into the motor, most small machines do, so look at the motor rating, say 1KW and toddle off to say Screwfix and buy a standard motor starter for that power rating. They don’t come with a an over current trip and cost c£25. I would wire in some form of visual signal that the extractor is on such as a light to remaind you to switch it off. When my workshop was in the garage and the extractor in a lean to, I used a coloured light bulb. Amazing how often it acted as a visual que to switch off the extractor!

I agree that machines such as saws, pillar drills, planers etc all need a NVR switch but an extractor?
Most NVR switches are just a latching relay which can be bypassed by bridging the in/out terminals and use the switch on the 13a socket or a remote controller. What do motor starters and over current protectors have to do with it when only the switch has been changed?

 

[Distinterior]

I have a Jet chip extractor in my workshop that is only about 3 years old .....And, it does not have an NVR switch fitted to it.
It has a flip on/off switch on it.....!!

 

[Seiken]

I have a SIP dust extractor, there is no NVR just a rocker switch. NVRs on extractors are just a pain when you want to remote switch, as to safety there are no exposed sharp spinning cutters, chucks, etc., to damage you with. I also do not see what motor starters have to do with it, if the extractor is not fitted with one there is no advantage in adding one. Bypass or remove the NVR on the extractor so it can be switched from where you want using a suitably rated switch, if you want a visual reminder its on use a switch or socket with a neon indicator. As CHJ says just make sure its unplugged before putting soft fleshy bits near metal spinney bits.

 

[deema]

The closest I have ever come to loosing my entire hand was with a dust extractor. They come with a grill to stop hands getting into the impeller, however the grill often ends up getting blocked and again inevitable you find that some bright spark has cut them out. My hand was near the inlet without any piping attached and it was accidentally switched on, my hand and arm were sucked in.....this was a smallish unit that could have been used in a hobby shop......fortunately the grill was still in place......I was going to remove the build up of shavings.

I can tell you was in deep shock afterwards, it literally frightened me silly.

An NVR is essential on any moving machinery.

 

[CHJ]

The closest I have ever come to loosing my entire hand was with a dust extractor. T..........fortunately the grill was still in place......I was going to remove the build up of shavings.

I can tell you was in deep shock afterwards, it literally frightened me silly.

....

What on earth were you doing attempting to service the machine without disconnecting it from its power source.

NVR or no NVR switches fail, and there is no guarantee it won't be in the made or intermittent condition, contacts can weld together.

 

[Mike Jordan]

I have an extractor in a separate room. The NVR switch has been bypassed and the power is supplied direct from the workshop through a cord operated switch of the type used in bathrooms to operate heaters. The switch is mounted horizontally and the cord has been extended through the length of the workshop ceiling using vine eyes and the end secured so that vertical pull cords could be installed at three convenient points near machines.
It's worked well for about twenty years now, my only regret is that I can't claim to have invented the idea since I copied to from a fellow woodworker.

 

[Bm101]

Could you guys answer a question for me please to clarify. Is the sole use of an nvr that in case of a power failure while a machine is in use it won't restart as soon as power is restored.
I've fitted an emergency stop to my refurbed meddings drill (not yet in use) but I also have an inca bandsaw and a p/t. Should I fit nvrs to all these machines as standard? I'm confident that in my wee shed I'd have the memory to remember what I was using in case of power failure (they get little use) but having said that... 60 odd notes for 3 switches is a small pay for 5 fingers on each hand.
Could I not just buy an nvr type plug for my limited use?

Cheers as always.
Chris

 

[Mike Jordan]

 

[Mike Jordan]

 

[CHJ]

Could you guys answer a question for me please to clarify. Is the sole use of an nvr that in case of a power failure while a machine is in use it won't restart as soon as power is restored.

Correct for a plain NVR switch, such as fitted to the likes of smaller DIY level equipment. Just stops it restarting when power source is re-established.

Some machines such as bigger Lathes and those that can be subjected to heavy in use loads also have current limiiting built into the starter unit where the NVR switch is housed, bypassing those units risks overheating the motor if you stall it or overload it for a prolonged period for any reason.

 

[Bm101]

Thank you. Much appreciated as always.

 

[CHJ]

If you want more detailed information on how to recognise the difference etc. have a look at Myfordmans excellent paper on the subject, (pages 14-19 or there about)

 

[Sideways]

Could you guys answer a question for me please to clarify. Is the sole use of an nvr that in case of a power failure while a machine is in use it won't restart as soon as power is restored.
...
Chris

For our purposes , yes.
What we probably think of as "larger" motors need a "starter" that protects them if they draw (i) too much surge current during startup and (ii) excess current once they're operating. These two are different so two types of protection are needed. The answer is often to fit the motor with a "DOL" or "Direct On Line" starter that includes both types of protection and a No Volt Release switch in the same box.
Loads of small motors 2 hp and under (?) ignore a lot of this and may have a really basic NVR switch with out the overload protection or as many posters have said, just a simple on/off switch.
Whatever you use you need to have a safe way of "isolating" it. If it's on a plug, switch it off and pull the plug out. If it's going to be permanently wired in, I suggest you do like the proper workshops do and wire it through one of those red and yellow rotary "disconnector" switches which are the place where the fixed wiring changes to the the flexible cable to the machine. They're not very expensive.
Cheers

 

[user22161]

The Kedu KJD12 is used on my TS ,PT, BS, DP & Extractor. This simple 4 contact one is just a double pole switch with a relay. When the green is pressed it physically pushes the relay contacts closed and then the voltage holds it that way until either the red is pressed or there's a power failure, to break the supply. Others can be more complicated and serve several functions.

https://www.amazon.co.uk/s/ref=nb_sb_no ... kedu+kjd12

 

[Sideways]

Good advice. These are used on lots of machines. It's a good general replacement for motors up to 1.5hp / 1.1kW. Look at the KJD17 for motors upto 2hp / 1.5kW.

 

[Bm101]

Many thanks all for the advice. Much appreciated. Hope I haven't gone too off topic.