New NVR switch for Naerok Pillar Drill.

[Bo’sunParticipant @bosun58570]

Good morning,

I needed to replace the NVR switch on my Naerok GP16P Pillar Drill.  Firstly the NVR had failed, and secondly the factory switch was on the LH side of the head and awkward to operate, especially if you wanted to turn the drill off quickly.

My plan was to fit an Axminster KEDU KJD12 NVR switch on a right angle bracket to improve accessibility.  I’ve fitted 3 of these to other machines in the workshop without any concerns.  It’s a double pole switch with live & neutral in, and live & neutral out.

However. the GEC type BC2510 motor on my drill has four conductors, brown (T3), black (T2), blue (no terminal ID) and yellow/green (earth).  Terminals T1 and T4 are empty.  The motor has a single capacitor.

The factory fit NVR switch has separate switch and coil. The brown and blue conductors go to the coil, and black to the switch.

How do I connect this motor to the new NVR switch?

Thanks.

 

[BazyleParticipant @bazyle]

Not enough information to give any help. Like where are the mains input wires going. What is the switch part of the current NVR connected to – you only gave the coil info.

If the factory switch is still connected draw out the full circuit as it stands.

[Bo’sunParticipant @bosun58570]

Hi Bazyle,

The mains input wires (brown & blue) go to the coil contacts, which, when the coil is energised, connect to the brown & blue wires going to the motor.

The switch has one wire connected to the brown side coil contact (along with the mains in), and another wire connected to the coil itself.

Not sure if this has made matters worse?  I’m endeavouring to draw out the circuit as best I can.

It’s the black wire going from the switch to the motor the seems odd (well to me at least), compared to the other 3 machines I’ve successfully added NVR’s to that don’t have this extra wire.

[Robin DuftonParticipant @robindufton85682]

Sounds like the original NVR has a provision for safety interlocks, or A1 terminal. If you search for NVR switches with the A1 terminal you’ll find plenty on people falling foul of them. The black wire is probably a thermal switch in the motor and connected to the A1 terminal. I’d disconnect the black wire from the motor and wire the new NVR up as normal.

[Benedict WhiteParticipant @benedictwhite51126]

Could you post a picture of the connections to the motor?

 

Usually with a single phase motor, you would see either 2 wires and earth or 4 wires and earth if the reversing contacts are available.

 

So having two and earth would be normal and you would just connect them. Note that it does not matter which way around they go, the motor will spin the same way as which way it spins is set by the relationship between the main coil and the starting coil. (This can be reversed with a reversing switch like a drum reverser if 4 wires plus earth are available).

 

I can post links to videos of 2 and 4 wire induction motor wiring if that helps.

[Bo’sunParticipant @bosun58570]

Thank you Robin & Benedict,

Sorry, but I do not possess the technology to post a picture.  Even if I could, I’m not sure it would be very clear and easy to see what’s going on.

It’s a little awkward to see, as the connections are on the end of the motor that’s pointing downwards.  However, with the help of a mirror and a willing assistant I can say the following:  The brown conductor goes to terminal T3, the blue conductor to an unlabeled terminal, and the black conductor to terminal T2.  The fourth conductor (earth) is connected directly to the incoming mains earth.

All seems logical with live & neutral in and out of the NVR coil, it’s the black conductor that goes into the separate switch that I don’t know what to do with.  I’ve had several suggestions that the black conductor may be a thermal overload for the motor.  If that’s the case, might I expect to see it connected to a relay?.

I’m tempted, as Robin suggests, to leave it unconnected and see what happens?

[Benedict WhiteParticipant @benedictwhite51126]

Ah. I see your problem. It is wired with 3 wires plus earth at the moment. Not sure how that works on single phase.

 

Have you tried googling the wiring diagram of the original setup?

[Robin DuftonParticipant @robindufton85682]

Disconnect the black wire both ends and tape it up or stick the ends in a Wago. If the other end is connected to a live connection inside the motor you’ll have a hot wire loose in your switch. By leaving it unconnected worse case you’ll pop a fuse or breaker, or the motor may not move and make an awful noise, so you’ll just have to be quick turning the power off.

[Bo’sunParticipant @bosun58570]

Thanks for your input guys.  What’s the worst that can happen?

Benedict, I’ve Googled until I can Google no more.  The Naerok GP16P drilling machine is around 30 years old, so any chance of a wiring diagram is like the infamous rocking horse poo.  Googling the GEC BC2510 motor doesn’t yield any information either.

If the black conductor is for a thermal overload, why on a drilling machine that generally only sees intermittent usage?  Maybe on a lathe or milling machine.

Oh well, in for a penny, in for a pound.  I’ll report back.

[Benedict WhiteParticipant @benedictwhite51126]

30 years old doesn’t mean there’s no information out there, Try googling the Brook Motors Gryphon motor (from the 50s and 60s). Also I was able to find information for my Naerok mill of a similar age.

 

Try different search engines or ask one of the AI ones like Bing AI or Chat GPT.

[Robin DuftonParticipant @robindufton85682]

Naerok built milling machines so it was no doubt cheaper to buy in one type of motor with a thermal overload than two variants, with or without, of the same motor.

[Benedict WhiteParticipant @benedictwhite51126]

Just had a look at the PDF manual for my Naerok mill/drill and it does not have anything about the motor.

 

I did make a video on fixing the motor (Link here) but I did not do one on the wiring. (I have for others).

 

A quick search on images on Duck Duck Go did find this picture from this page which does show a blue, red and black wire where the black wire is where you connect instead of the red to reverse though that is for a geared motor.

 

Hope that helps.

[Bo’sunParticipant @bosun58570]

I’ll keep searching, but BING hasn’t yielded anything regarding the black conductor.

That’s a good point Robin, but why not just add a normal 3 core cable and leave terminal T2 (black conductor) empty?

I’m now beginning to wonder if I need a different NVR switch with a terminal for the black conductor?

[Bo’sunParticipant @bosun58570]

Thanks Benedict, I also found that diagram via BING, but it appears to be for a reversing switch, which I don’t have (or need) on my drilling machine.

[Bo’sun]

On Bo’sun Said:

Thanks Benedict, I also found that diagram via BING, but it appears to be for a reversing switch, which I don’t have (or need) on my drilling machine.

The reason for posting it is to show why you might have 3 wires, rather than a suggestion to fit a reversing switch. The implication is that you can just ignore (but make safe as it will be live when  the motor is running) the extra wire.

[Bo’sunParticipant @bosun58570]

Good afternoon,

I haven’t reconnected anything yet.  Just configured a mounting arrangement for the new NVR switch, and extended the motor cable to reach the new switch.  However, I noticed today (why I didn’t see it before I don’t know) the motor has a reset button, so presumably it does have a thermal overload.

How do I tell if the “black conductor” is related?

[noel shelleyParticipant @noelshelley55608]

The thermal cutout will be an internal bi metal switch, hence the reset button. ME had a circuit diagram for a NVR under the title Smoke Signals about 3 years ago. The picture shown in the link is misleading and should read L1 and N, not L2. I take it no pictures or notes were made before disconnection of the old switch. Motor on 4 bolts ? Drop off motor so that the wiring can be studied, 2 wires or 4 is normal, unless it is a special. Careful use of a multimeter should tell whats going on. The basic NVR switch is simple, a coil/relay and 2 switches one N/O and the other N/C. When the N/O sw is closed the coil will come in and one set of contacts will hold it, operating the N/C sw will break the ciruit and the power cut off. Good Luck, Noel

[Bo’sunParticipant @bosun58570]

Thank you Noel,

Just to summarize.

I expected the motor to have N, L & E conductors as others I’ve added NVR switches to (simple – L&N in L&N out).  However, this GEC motor has an extra black conductor.  The NVR switch I’m replacing has a coil and separate switch.  L&N go in and out of the coil as expected, and the black conductor goes to the switch.  The paddle switch is normally “off”,  It moves through latching “on” to momentary “on” and the motor starts, until returned to the “off” position.  Unfortunately, the new NVR (KEDU KJD12) has no terminal for the extra black conductor.  With the Drill Press being over 30 years old, I can find no information about the motor or NVR coil/switch configuration.

[noel shelleyParticipant @noelshelley55608]

Until the purpose of the black wire is known I see no way forward. You talk of latching on and momentary on. Is the original switch as built or has it been fitted later ? Is the motor original, has the centrifugal switch failed and this is a bodge job at some point ?  On grounds of safety I would check the motor wiring it sounds a bit suspect.  The new switch has no terminal for the 3rd wire as one should not be needed ! What make was the original NVR/ switch ?

If the old NVR was an MEM Etc and 3Ph with a 240V coil then wiring inside the box could provide the terminal that is now missing for the black wire – I would tread with caution, I smell a rat ! Noel.

[Bo’sunParticipant @bosun58570]

Good morning Noel,

Everything on the Pillar drill is original, I’ve had it from new.  With respect to the switch, it has three positions (I think it’s referred to as a “paddle switch”).  First position is OFF, next position ON (latched, but no motor run), final position is momentary which starts the motor, the switch then returns to the previous ON position with motor running.

The switch is from Arrow, England, but no ID on the coil.  The NVR switch assembly was two separate parts, the switch and the coil.

I should point out that the drill was functioning OK apart from a temperamental NVR/switch (occasionally, the motor wouldn’t start on the momentary switch position), and it was also a good excuse to relocate the ON/OFF controls to a safer and more convenient location.  They were mounted on the side of the head where you couldn’t easily see them, or turn the machine off quickly.

I hope this helps clarify things.

[noel shelleyParticipant @noelshelley55608]

Hey Bosun, forgive me asking but what is the extent of your electrical knowledge ? Testing with a meter should tell you what is what. In most cases the motor is a simple device with 2 sets of windings, giving 4 wires, a centrifugal switch and a capacitor (or 2). The way in which the connections are made will decide the direction of rotation. These connections are normally made on the motors terminal plate and give just the live and neutral to be supplied. a reversing switch slightly complicates things.With the new site not being so good I fancy that some of the regulars have left that might have offered help. The fact that the motor has 3 wires + earth and the black wires purpose is unknown, so as I said before only by knowing the function of the black wire can you wire it up safely. It is unfortunate that no notes were made when the old switch was removed. Where abouts are you in the UK ? Good luck Noel.

[Bo’sunParticipant @bosun58570]

Hi Noel, thanks for the prompt response,

In answer to your question, I am a qualified mechanical engineer with a little electrical knowledge, the extent to which you may have guessed.  Having successfully added the same NVR switches to three other workshop machines (a wood lathe, a disc sander and a buffing machine), I was expecting equal success with the Pillar Drill.  How wrong one can be!  Unfortunately, regarding notes, expecting the Pillar Drill to be the same as the others I just severed the cables only to find the infamous black conductor.

I’m in Essex by the way.

It sounds like I’m not the only one that thinks the new site is a backward step.

[Robin DuftonParticipant @robindufton85682]

We know what the black wire is for, it’s a thermal switch. Either remove the black wire and fit the new NVR switch to the live and neutral, leaving the thermal switch unconnected. Or buy an NVR switch with the terminal for interlock switches and wire it to that. It’s quite straight forward and there’s no need to confuse things further.

[Bo’sunParticipant @bosun58570]

Good afternoon All,

Just an update on the NVR switch for my Naerok Pillar Drill.

After some searching, I found a KEDU KJD17 FT NVR switch with the infamous 5th terminal.

Fitted it this afternoon, and so far, all is fine and dandy.  I guess I won’t know if the thermal overload/5th terminal is functioning correctly, until it’s needed.

[Robin DuftonParticipant @robindufton85682]

That’s good news. The extra terminal would also be useful to wire in a foot operated kill switch, if you wanted to.

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