Lathe motor replacement

This topic has 43 replies, 11 voices, and was last updated 3 February 2017 at 12:45 by Toby.

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15 January 2017 at 16:34 #277957
Hevanscc
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@hevanscc
The 1 phase motor on my viceroy lathe finally gave up, as evidenced by clouds of smoke and charred windings. So I have decided to replace it with a 3 phase motor and inverter combo to run off 1 phase supply. As I await delivery there are a couple of questions I have before I wire it up.
1. Is it ok to wire the 1 phase supply into the existing NV switch before the inverter? I think that I am right in thinking this after reading other threads. There is a photo in my ‘viceroy lathe’ albumn with what I think is a reversing switch wired in.
2. Can I use said reversing switch to reverse the supply, and hence direction of motor rotation, with the inverter wired up or should I get rid of it and use a separate reversing switch that works on the ouputs from the inverter?

Thanks for any advice
Hywel

Edited By Hywel Evans on 15/01/2017 16:36:18

Edited By Hywel Evans on 15/01/2017 16:37:21

Edited By Hywel Evans on 15/01/2017 16:39:12

Edited By Hywel Evans on 15/01/2017 16:40:40

Edited By Hywel Evans on 15/01/2017 16:42:26

Edited By Hywel Evans on 15/01/2017 16:42:54
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15 January 2017 at 16:34 #18366
Hevanscc
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@hevanscc
15 January 2017 at 17:16 #277966
Martin Cargill
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@martincargill50290
1. You need to check the inverter installation manual with regard to what the manufacturer wants in the line to the inverter, some of them require a contactor feeding it, some don't.

2. The reversing switch on the single phase motor would probably be reversing the feed to the start winding/capacitor (on the 3 phase version of your machine it would be swapping two of the incoming phases). You can't simply wire the existing electrics into the inverter. Having said that you probably can use the existing switches after rewiring the machine.

Best solution is to ask the supplier and read the installation manual. A good supplier will be able to give you guidance as to how to set up the parameters on the drive and give you guidance on the best way to fit/wire it.

Martin
15 January 2017 at 17:18 #277967
Clive Foster
Participant
@clivefoster55965
Best practice is to have a switch or isolator on the incoming supply and use the inverter controls for everything else. Easiest, and probably not that much more expensive than DIY, to buy a pendant or control box made to work with your inverter. Wired my own in the past but these days I'd just get the pre-made box, despite having suitable components to hand, saving all the hassle and futzing about. If you are not set-up and ready its an easy 2 or 3 hours to make a box and not that much less to splice something in based on what's on the machine. Just sorting out the which connection goes where can be a serious puzzle for the uninitiated. Sometimes life is too short!

Clive.

Edited By Clive Foster on 15/01/2017 17:20:10
15 January 2017 at 18:12 #277976
I.M. OUTAHERE
Participant
@i-m-outahere
You won't need a NV switch or your old reverse switch , the default setting for the inverter should be set to motor off and all you need is a toggle switch wired into the reverse terminal on the inverter to rerse the motor although you could possibly use your old switch for this .

You will need start and stop buttons and you can also have a jog button , an emergency stop button gets wired into the fault terminal once again depending on what type of switches your machine has ( momentary or latching ) you may be able to use them on the inverter

The other option is to mount the inverter directly above the head of the lathe and use the little control panel on it and just wire in your emergency stop using the old switch if it has one.

My inverter manual stated it is not recommended to have any sort of switch between the motor and the inverter as it can damage the power transistors .
15 January 2017 at 18:35 #277983
Brian Oldford
Participant
@brianoldford70365
Posted by Martin Cargill on 15/01/2017 17:16:49:

. . . . . .

2. The reversing switch on the single phase motor would probably be reversing the feed to the start winding/capacitor (on the 3 phase version of your machine it would be swapping two of the incoming phases). You can't simply wire the existing electrics into the inverter. Having said that you probably can use the existing switches after rewiring the machine.

. . . . . . .

Martin

All the Dewhurst switches I've seen can be wired to either reverse the phase of the start winding in the case of a single phase motor or transpose two phases in the case of a three phase motor. Beware, this might take a bit of figuring out to a non-electrically savvy person.

Edited By Brian Oldford on 15/01/2017 18:49:06
15 January 2017 at 19:13 #277991
Ian P
Participant
@ianp
To summarise most of what has been said in the previous replies.

The VFD already functions as a NVR switch (unless you reconfigure it) as by default it will not let the motor run until it gets a valid start command on one of its digital input terminals.

In theory, for a fractional HP motor you do not need any contactor or isolator on the input of the VFD if its fitted with a 13A.

Whatever the existing switches and controls are its more than likely they will be suitable to act as stop/start and reversing controls. Most VFDs just require a simple contact closures to select the functions. Its unlikely you will find the controls on the front of VFD easy to use, partly because its not easy to put the VFD where they are convenient, but also up/down buttons are not ideal for the speed control. Wiring a potentiometer in a convenient position is much better. (three wires)

Before you start wiring up any switches think how you want to control the lathe. On my lathe and mill I have a three position toggle switch, FWD in the down position, REV in the up position, centre OFF. I imagine any existing switch (Drum type) would be ideal for the same purpose and would only need three low voltage wires to connect it to the VFD.

I'm not a fan of 'stickies' but 'VFD usage' and (dare I say it) 'Lathe levelling' are both crying out for definitive guidance

Ian P

With a 13A plug that is within easy reach, is what I meant to say.

Edited By Ian Phillips on 15/01/2017 19:14:17
15 January 2017 at 19:18 #277994
Martin Cargill
Participant
@martincargill50290
My own preference for this type of conversion is to use existing switches, knobs etc, for their original functions. This way there is no need to have to re-label control panels and anyone who has operated a similar machine will have no problems in finding the relevant controls.

The other consideration for inverter installation is the buttons provided on the unit are fine for testing or setting up the unit but are probably not the best in terms of durability for daily operation, nor are they very big. Its much better to have proper industrial type control gear that is designed for the job.

The.other thing to consider is that the inverter is not the best thing to mount on top or adjacent to the machine as (to my mind) they are not the most robust of items and will come off second best in an impact situation. They are often not provided with the best ingress protection when dealing with swarf etc. Installing them in a suitable enclosure is better for them and (in the case of a metal enclosure) can also help with EMC/RF issues.

Anyone who can operate a multimeter and has the competence to install an inverter should be able to re-configure the electrics on a machine to work with an inverter. If you don't feel that your competence extends this far then you should be seeking advice from someone who does!!!!

Martin

PS Ian has just said almost the same things as I was typing this post

Edited By Martin Cargill on 15/01/2017 19:19:36

Edited By Martin Cargill on 15/01/2017 19:21:36
15 January 2017 at 19:33 #277998
John Rudd
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@johnrudd16576
Should the inverter be installed in an enclosure, consideration needs to be given to ensure there is sufficient cooling to prevent any possible overheat scenario…..
15 January 2017 at 19:33 #277999
Hevanscc
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@hevanscc
Thanks for all the replies. I just downloaded the manual and it reccomends using a magnetic contactor. So I am thinking to get rid of the existing switchgear and replace with contactors for on and off. I was planning on mounting the inverter in the cabinet beneath the lathe _ this is enclosed like a boxford so no danger of swarf. The inverter actually has a knob on it to control speed but I can get a pot to mount on the faceplate with the contactors to make this easier to get at – instructions come with the inverter to do this.

Hywel
15 January 2017 at 19:36 #278000
Martin Cargill
Participant
@martincargill50290
Hywel

I've just re read your original post and perhaps realise that you are asking if you can use the old 3 phase reversing switch to switch motor direction by having this wired between the inverter and the motor.

This is not a suitable method.

The drive unit will have low voltage control inputs for start/stop/reverse etc and it is possible (and sensible) to re configure the wiring to use the old switches to feed these inputs.

Martin

PS just read your last post. The existing contactor should be able to power the invertor. The inputs to the inverter controls only require pushbuttons and not contactors. Can you give us a link to the manual ?

PPS I have two Viceroys so I know the controls fitted to them.

Edited By Martin Cargill on 15/01/2017 19:40:59

Edited By Martin Cargill on 15/01/2017 19:42:35
15 January 2017 at 19:59 #278003
Hevanscc
Participant
@hevanscc
The manual is here
https://inverterdrive.com/group/AC-Inverter-Drives-230V/LS-Starvert-Inverter-750W-230V-SV008iC5-1F/

I don’t think my viceroy has the original switches because an extra hole has been drilled in the enclosure for the start switch – the old faceplate, which was in the cabinet, does not match up.
15 January 2017 at 20:15 #278004
Ian P
Participant
@ianp
Posted by Hywel Evans on 15/01/2017 19:33:58:
Thanks for all the replies. I just downloaded the manual and it reccomends using a magnetic contactor. So I am thinking to get rid of the existing switchgear and replace with contactors for on and off. I was planning on mounting the inverter in the cabinet beneath the lathe _ this is enclosed like a boxford so no danger of swarf. The inverter actually has a knob on it to control speed but I can get a pot to mount on the faceplate with the contactors to make this easier to get at – instructions come with the inverter to do this.

Hywel

Hywel

I just skimmed through both manuals but did not spot where it recommended using a magnetic contactor. I can see that a contactor might be worthwhile if using a large, high current motor but for a FHP motor any normal switch that can handle the current should be fine.

What do you mean above by using 'contactors for on and off''?

Ian P
15 January 2017 at 20:21 #278007
Hevanscc
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@hevanscc
Page 4-1 mentions the contactors, but it also says not to use for stopping or starting – not sure what that means to be honest, I’ll need to do more research by the look of it.
15 January 2017 at 21:19 #278027
Toby
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@toby
Posted by Hywel Evans on 15/01/2017 20:21:53:
Page 4-1 mentions the contactors, but it also says not to use for stopping or starting – not sure what that means to be honest, I'll need to do more research by the look of it.

The point they are making is that you should use the inverter for turning the motor on and off. Any switch in the incoming supply should only be used when the motor is already off. Or an emergency.

Same for reverse, it is not a good idea to switch the 3 phases to the motor unless you can guarantee the motor is off when doing so. Again better to use the inverter to do reverse.

Toby
15 January 2017 at 23:13 #278057
Ajohnw
Participant
@ajohnw51620
The reason they mention a contactor is that some inverters take way more current than switches can easily handle. If you fit one it would usually finish up wired to be used in an NVR fashion. You might just use an NVR switch to do it on something that can run off a 13amp plug. There shouldn't be any need though as the inverter will behave like an NVR switch. Remove the volts say due to a mains failure and when it comes back the inverter wont switch the motor back on. Or shouldn't.

There is a bit of a catch though. When powered up inverters take a big gulp of current which isn't good for contacts in switches. Best to use one that is over rated for the job.

There can be a need to isolate the inverter so some sort of switch should be fitted. An oridnary NVR could be used but isn't ideal for fault conditions that shouldn't happen which could cause the on contacts to weld. You could use a panic stop button – they are used because the button actually forces the contacts apart. A better option which does the same thing is a rotary on of switch. It's obviously on or off. A panic button could also be added after that for panics and nothing else.

One option as they can be bought all in one box might be an nvr switch and a panic button.

It's all an area where people tend to do what they do rather than follow a set of rules. If the machine is owned by a business things get a bit different,

John

=

Edited By Ajohnw on 15/01/2017 23:14:01
16 January 2017 at 08:50 #278089
Hevanscc
Participant
@hevanscc
It seems that the easiest and safest option is to do away with the existing switch and replace with a pendant remote controller. As Clive says, the time spent faffing around making your own (if like me you have to learn to do it first) means that I might as well buy one. Does anyone have any reccomendations – I've seen some comment about poor ergonomic design on the forum. The outputs are 24 V and 12 V for the potentiometer.

Hywel

Edited By Hywel Evans on 16/01/2017 08:53:29
16 January 2017 at 09:13 #278092
Toby
Participant
@toby
Posted by Hywel Evans on 16/01/2017 08:50:20:

It seems that the easiest and safest option is to do away with the existing switch and replace with a pendant remote controller. As Clive says, the time spent faffing around making your own (if like me you have to learn to do it first) means that I might as well buy one. Does anyone have any reccomendations – I've seen some comment about poor ergonomic design on the forum. The outputs are 24 V and 12 V for the potentiometer.

Hywel

Edited By Hywel Evans on 16/01/2017 08:53:29

Horses for courses really. On my lathe I made my own control panel, on my drill I am re-using the drills start/stop switches to control the inverter but not using the existing contactor, E-stop etc.

I don't have any experience of using a ready built control panel/pendant though.
16 January 2017 at 09:43 #278100
Ian P
Participant
@ianp
Posted by Toby on 16/01/2017 09:08:41:

Hywel, I don't know if this will help, but here is a block diagram of a inverter system. It is obviously generic so might not be exactly what suits your lathe but hopefully will explain what the various blocks do and how they relate to your existing wiring…..

If anyone can see any major ommissions or mistakes on this let me know!

Edited By Toby on 16/01/2017 09:09:47

Toby

The block diagram you showed does not have a major omission, but rather too much confusing information!

The last thing that block diagram should show is a reversing switch in that position, in fact in any position!

The text says it is not recommended so why show it in the first place.

All a VFD block diagram need is a box containing the VFD and a box containing the motor. Another box to show the main power switch (NVR/Isolator or whatever) and a box showing the potentiometer and switches.

Ian P
16 January 2017 at 09:47 #278104
John Rudd
Participant
@johnrudd16576
Toby,

Distinct lack of over current protection on the incoming mains side to the inverter……either a fuse or an mcb….

I see a switched fuse spur, but, that also powers other ancilliaries.

As previously stated, no hard and fast rules, use the guidance offered and do what suits you without putting yourself in danger….
16 January 2017 at 09:51 #278107
Toby
Participant
@toby
Posted by Ian Phillips on 16/01/2017 09:43:44:

Posted by Toby on 16/01/2017 09:08:41:

Hywel, I don't know if this will help, but here is a block diagram of a inverter system. It is obviously generic so might not be exactly what suits your lathe but hopefully will explain what the various blocks do and how they relate to your existing wiring…..

If anyone can see any major ommissions or mistakes on this let me know!

Edited By Toby on 16/01/2017 09:09:47

Toby

The block diagram you showed does not have a major omission, but rather too much confusing information!

The last thing that block diagram should show is a reversing switch in that position, in fact in any position!

The text says it is not recommended so why show it in the first place.

All a VFD block diagram need is a box containing the VFD and a box containing the motor. Another box to show the main power switch (NVR/Isolator or whatever) and a box showing the potentiometer and switches.

Ian P

Thanks for the feedback Ian.

The reason I put the reversing switch in is that it often comes up when people want to re-use the existing wiring and existing switch and I am sure I have read here people saying they have used it in the location shown. So I didn't want to ignore it.

Same goes for the output filters (reactors). Personally I would not fit one unless there was a proven need, but others have for good reason. Hence the optional bit.

If someone wants just a basic block diagram showing the inverter and motor and controls then they are best looking in the inverter manual. That will also show the control configuration which might be specific to the inverter.

That was my reasoning anyway, what do others think?
16 January 2017 at 10:02 #278114
Toby
Participant
@toby
Posted by John Rudd on 16/01/2017 09:47:22:

Toby,

Distinct lack of over current protection on the incoming mains side to the inverter……either a fuse or an mcb….

I see a switched fuse spur, but, that also powers other ancilliaries.

As previously stated, no hard and fast rules, use the guidance offered and do what suits you without putting yourself in danger….

A good point but I am struggling to see how to update the diagram without making it over-complicated (especially considering Ian's comment). I guess as a starting point I should state that the isolator should also contain a fuse/protection if there is not adequate elsewhere. That would cover the situation of a fused plug, fused connection unit or switched outlet with seperate MCBs etc.

Perhaps I should also remove the 230V supply to other equipment as where that it taken from depends on what that equipment is, what fuse it needs and whether it needs a separate isolator.

I knew I was going to regret posting that
16 January 2017 at 10:31 #278123
Mark C
Participant
@markc
Hywel, Reading your first post and looking at your pictures – I will take a guess that your lathe used to work by selecting forwards or reverse direction with the black knob and then pressing the green button started it up and the red button turned it off?

If that is the case then you are half way to having everything you need for an inverter. As you mention it is single phase I will also guess that it plugs into the wall socket?

If that is the case, then take the supply from the plug directly into the inverter supply side. Then, rewire the original direction, start and stop switches on the low voltage control side of the inverter. You will need to follow the instructions (there will be a wiring diagram in the manual) for the correct method of linking the two switches which will be "momentary" push button switches and need to be wired to latch (done internally in the inverter by electrickary). You then simply connect the motor directly to the inverter output and program the inverter with the correct parameters – another manual reading exercise unfortunately…

I hope that helps, I have two Boxfords wired like this (although mine do not plug in, they are wired permanently to switched spurs supplied from dedicated MCB's in the distribution board). Take care with the air flow requirements when you box in the inverter!

Mark

Edited By Mark C on 16/01/2017 10:32:40

Just read your manual, you need to read the page about three wire control wiring on page 10-5 (advanced section). I did not read it completely, you will need to check the inputs to confirm that is start, stop and direction switches but it certainly looks like it…

Edited By Mark C on 16/01/2017 10:38:37
16 January 2017 at 18:43 #278259
Mark C
Participant
@markc
Hywel, Rather than another thousand words, here are some pictures of my lathe installations. The VSL has an old inverter on the brick wall at the back but the other Boxford has the same sort of setup that you are doing (I think) with the inverter located in the lathe cabinet behind the control panel. The VSL is different in that it has the original rotary switch wired to the inverter to set direction and then start (the switch is 5 positions, centre off, detent in first position either side of off with a momentary start position if you keep turning the switch which then springs back to the first position – this is how they originally worked but it is all done by the inverter logic now). All my machines have a separate E-Stop fitted (wired as required by the inverters).

The lathe is permenantly wired as mentioned earlier and you can see the switched spur on the wall at the back on this picture

VSL looks like this (the white knob is the multifunction switch)

Hope this helps a bit

Mark
17 January 2017 at 08:19 #278338
Hevanscc
Participant
@hevanscc
Posted by Mark C on 16/01/2017 18:43:43:

Hywel, Rather than another thousand words, here are some pictures of my lathe installations. The VSL has an old inverter on the brick wall at the back but the other Boxford has the same sort of setup that you are doing (I think) with the inverter located in the lathe cabinet behind the control panel. The VSL is different in that it has the original rotary switch wired to the inverter to set direction and then start (the switch is 5 positions, centre off, detent in first position either side of off with a momentary start position if you keep turning the switch which then springs back to the first position – this is how they originally worked but it is all done by the inverter logic now). All my machines have a separate E-Stop fitted (wired as required by the inverters).

The lathe is permenantly wired as mentioned earlier and you can see the switched spur on the wall at the back on this picture

VSL looks like this (the white knob is the multifunction switch)

Hope this helps a bit

Mark

Thanks for the pictures Mark, very useful. I have now done away with all the existing switchgear because I was not confident enough to start fiddling with it. The motor is in place and wired. Now I need to wire in the inverter and mount in the cabinet. I will use it by controlling the the motor from the inverter box at first then see about using a pendant or maybe mounting remote controls in the original switchgear enclosure and make use of the original Viceroy faceplate so it all looks tidy . . . maybe. When I get around to that bit, the information here will be very useful, but for now I just need to get the lathe working again to finish the project which is currently still mounted in the 4-jaw chuck since the motor went boom.

Many thanks

Hywel
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