Member postings for Les Jones 1

You can probably use the NVR switch that you have. Post some pictures of it so I can check if one end of the coil can be accessed. If it can I will post a diagram of how to connect it.

Les.

That switch can be used both for single phase or three phase. It does not even need any change made to the links between terminals. The only thing that I would recommend is using a contactor with thermal overloads with start and stop buttons. In that case the lower set of contacts on the reversing switch could be connected in series with the coil on the contactor. This would prevent switching directly between forward and reverse as if it was attempted the contactor would drop out as the reversing switch passed through the middle position. Using the stop and start buttons would also increase the life of the reversing switch. I cheaper alternative to a proper contactor would be an NVR switch that had the option of breaking the feed to the maintainer coil.

Well done Emgee in giving the solution to the problem in his post at 18:37 on 04/02/21

Les.

If the wire (Yellow or blue.) that had a short to earth was connected to terminal A (which is connected to neutral.) The motor would run without tripping an MCB (Or blowing a fuse) But it may trip an RCD.. This depends on voltage drop across the neutral conductor from the RCD. (I will not try to explain this in detail as it involves understanding exactly how RCDs work.) If the wire that had a short to earth was connected to Z then live would be connected to earth via the start capacitor which could trip an MCB (Or blow a fuse). If it only had leakage to earth rather than a dead short it would still trip the RCD.
Was it an MCB or the RCD that tripped out ?

Les.

This is my revised diagram.

Les.

I have no solid conclusions but here are some comments.
As a result of some further tests after I posted what I thought was the way it was wired at 9:27 on the 6th my diagram is wrong. The centrifugal switch is NOT connected between K and S which I had assumed as a result of the zero ohms reading in the post at 23:12 on the 5th and the fact that it would seem to connect the start and run capacitors in parallel. The post at 16:12 on the 6th now shows no continuity between K and S and Keith has since proved that what I thought MIGHT be a thermal cut out (Even though it not in the right place to remove the supply to both windings.) is in fact the centrifugal switch. I seems that there is nothing connected to K other than one wire from the run capacitor. When the motor ran with the original way the auxiliary winding (Yellow and blue wires) was connected I think it was just running as a capacitor start motor as one side or the run capacitor does not seem to be connected to anything. The only explanation I can see for swapping yellow and blue over is that one of them is shorting to (Or flashing over to.) earth. This is what Emgee suspected in his post at 18:37 on the 4th.

Keith, Can you check the insulation between the auxiliary winding (Yellow and blue wires) using an insulation tester / megger and earth. (It would be a good idea to test the insulation between the rest of the wiring and earth at the same time.)
Keith, Was the picture of the connection box taken before or after you swapped the blue and yellow wires over ?

I would be interested to here comments from Emgee and/or John Fletcher as they may have spotted something I have missed.

Les.

Edited By Les Jones 1 on 07/02/2021 11:09:34

Hi Keith,
Tracing the wires to the capacitors confirms that the markings fro the start and run capacitors is correct. The start capacitor will be the larger capacity of the two.)
When you refer to the switch is this the centrifugal switch and you managed to operate it manually ?
In your post at 23:12 on the 5th you say the resistance between K & S is zero ohms but today you say it is open circuit between K & S . Which is correct ?
I have tried to confirm that in your post at 13:12 on the 4th that the wiring in the motor connection box is the same as the diagram in the same post but could not see the marking of the top two terminals, Also I can not see which terminals some of the wires connect to. Can you confirm that it does match the diagram as you can move wires to see underneath them, (Apart from the yellow and blue being crossed over and assume this is after you swapped then over.)

Noel, I have never seen a centrifugal switch with change over contacts. I have only ever seen it wired to connect the start capacitor in parallel with the run capacitor during starting. Also I can see no problem with the diagram of the reversing switch that Nick has drawn in his post at 10:28 on the 5th. The top two contact sets are wired to reverse the polarity of the auxiliary winding and the bottom set cuts of the power to the motor in the middle stop position.

Les,

Edited By Les Jones 1 on 06/02/2021 17:51:06

I am assuming the wire that you call grey is the one marked black on the diagram. (And was connected to terminal A) Am I correct ?

Above is the way I think it is connected. but it looks like the marking for the start an run capacitors are the wrong way round. Can you follow the wires from the terminals to the capacitors and read the values of the capacitors so we know the values tied to the start and run capacitors as marked on the diagram from the motor.
With the 6 wires not connected to any of the terminals can you test for continuity between each of the 6 wires and all of the terminals. This is to see if there is any connections that are not visible. I suspect there is a connection that we don't know about as from the diagram I have traced out above swapping the blue and yellow wires is the correct way to reverse the motor and should not trip the breaker, I think the centrifugal switch is connected between terminals K and S. I would like to confirm this.There are a few ways to do this.1! dismantle the motor and follow the wires. 2 Spin the motor using an electric drill or other means to about 1500 RPM and check that there is no longer continuity between K and S, 3 With all the wires connect as originally connect your meter set to AC volts between S and K and apply power. There should be a short pause after applying power when there is no reading but once the motor is up to speed there should be some reading. This will probably be less than 240 volts.
4 Repeat the above but with the meter connected to K and Z. The meter should briefly read a voltage and drop to zero when the motor is up to speed.

Les.

If you swapped yellow and blue over as indicated on the motor diagram and it tripped the breaker then that information must be wrong. Am I correct in assuming that the motor ran with those wires in the original position ?
I am reasonably sure that the centrifugal switch is between terminals S and K
Assuming that you have a multimeter do the following. Remove the 6 wires that come from inside the motor from the terminals.Take resistance readings between all pairs of those 6 wires. (I think that will be 15 readings.) Your meter test leads will have some resistance (Probably less than 1 ohm.) so subtract that value from the displayed readings.
Also measure the resistance between terminals S and K (I think these are connections to the centrifugal switch which will be closed when the motor is stopped. Post the results of these tests.

Les.

The first reply to your post has a link to the instructions to post pictures on the forum,
Just click on the bold text to take you to the information.

Les.

Do you have a multimeter to work out the truth table for the switch and to identify the main an auxiliary windings on the motor ? Post as much information as you have on the switch and motor and pictures of the connection box on the motor and the switch showing any number / letter marking on the switch. Is the switch a two position or three position switch ?

Les.

You would need an extra stop button and start button.
Your suggested switching sequence is not a good one as you are using the reversing switch to switch under load which will shorten it's life. You should set the direction then switch on and off using the start and stop buttons.

I have used my mill in reverse on a few occasions. I think it was to use a boring tool from my lathe mounted in a boring head on the mill.

Les.

Edited By Les Jones 1 on 02/02/2021 12:00:15

Hi Steve,
The way you have show will work but it would make more sense to have a separate contactor for each motor.
Every time you change the feed direction the spindle motor will also have to stop and start.

Les.

Here is a diagram of how I suggest adding the reversing switch.

Connect the reversing switch as in Martin's drawing posted at 16:13 on Jan 24th.
Remove the link wire between the bottom mains input (I can't read the marking on it.) and the stop button. Connect the point X on Martins diagram to bottom mains input terminal on the contactor, Connect Y on Martin's diagram to the connection on the stop button that you removed the link from.

Les.

It would be better if you can provide information on the existing so we can tell you where to break the feed to the contactor coil. all of the interlocks, the thermal overload contacts and the stop button will probably be in series with the coil. Also we don't know if the contactor coil is powered between phases, between a phase and neutral or from the secondary of a low voltage transformer. Your existing wiring diagram should provide that information.

Les.

Reading through the thread again I notice you do have a contactor so here is a suggestion that would ensure the contactor dropped out when the switch passed through the middle off position.

Connect L1 directly to A on the motor.

Connect L2 to 6 and link 6 to 8.
Connect B on the motor to 5 and link 5 to 11

Connect L3 to 10 and link 10 to 12
connect C on the motor to 7 and link 7 to 9

Link 1 to 3 We will call this point X

Link 2 to 4 We will call this point Y

Break the feed to the contactor coil and connect the two ends of the break one to X and one to Y
This will cause the contactor to drop out when the switch passes through the middle off position.
You will then have to press the start button again after the switch has been set to either the forward or reverse positions.
As you have a contactor all three phases will be disconnected from the motor when the switch is in the off position.
Even if the switch is set to forward or reverse if the motor has been stopped with the stop button none of the phases will be connected to the motor. If you post the exiting wiring diagram and information on the contactor one of us will be able to tell you a suitable place to break the feed to the contactor coil.

Les.

Edited By Les Jones 1 on 24/01/2021 14:56:22

From the truth table Noel's instructions will only work in position 1. (Post 23/01/21 at 23:33)
It needs the following three links adding. 2 to 4, 6 to 8, and 10 to 12.

Edit. I see Martin has beat me to replying. His information will also work
Are you using a contactor and thermal overload ? If so the point made about arranging the wiring to make the contactor drop out in the middle off position is a good one. It would be even better is a delay circuit was added so that the contactor could not be activated for several seconds after it dropped out. This would prevent switching straight from forward to reverse.

Les.

Edited By Les Jones 1 on 24/01/2021 10:32:42

It looks like there is information on the left hand side of the switch between the connections. there is probably the same on the other side. If you post pictures of both sides it may avoid you having to meter out the connections.
The make and model number of the switch may enable use to find the data on the switch.

Les.

As John Rudd mentioned DON'T try to use a scope to fault find unless you supply the speed controller from an isolating transformer with a floating secondary. I suggest using a 60 or 100 watt incandescent light bulb as a load in place of the motor connected directly to the board. Also don't forget to link the connections that normally go to the interlock switches.

Les.

Here is a schematic for the XMT-2335 board in case you do not have one.

Arc Euro stock them under Seig X2 spares but they are £136.31.

Les.

Re my post on 08/01/21. The spindle that I ordered from China arrived today. There was nothing to pay.
(The collets that were ordered at the same time have not yet arrived.)

Les.