Member postings for Les Jones 1

Before applying a lot of force I suggest buying or making a key for the outside stopcock so you can turn off the water in the event of something breaking.

Les.

Does the motor run with no mechanical load on it ? (I.E the drive belt removed.) The larger value capacitor is the start capacitor. I think as it is a new motor you should Return it and get a replacement. Is it connected directly to the mains or via the internal lathe wiring ? I am surprised that Chester have supplied a Clarke motor. Is the connection information supplied with the motor identical to the first post of this thread ? If you want to do some investigation of the fault this is what I suggest. Remove the two link bars. Measure the resistance between U1 and U2. This will be the main winding and I would expect a resistance of less than 10 ohms. Measure the resistance between W1 and W2. This will be the auxiliary winding and it's resistance will be greater than the main winding. (But probably less than 20 ohms.) Measure the resistance between V1 an V2. This is the contacts on the centrifugal switch which should be closed when the motor is stopped and the reading should be very close to zero ohms. Report the readings and we can tell what is probably wrong with the motor. (Not that it really matters as you will have to return it as faulty.)

Les.

Edited By Les Jones 1 on 13/02/2021 18:05:25

Hi Noel,
I can see that the motor in your pictures has a changeover centrifugal switch but I don't understand how you KNOW that Keith's motor has this type of centrifugal switch. To reduce the number of conductors required between the motor and reversing switch I propose to swap over the blue and purple wires rather than the blue and yellow wires. (This is assuming yellow is connected to Z.) This is because the points A and AZ are already available at the reversing switch. If it is a changeover centrifugal switch I think the purple wire is the common of the changeover switch and the NO contact is connected to terminal K. BEFORE suggesting this I want to be SURE that there is no hidden connection between the main winding and auxiliary winding / capacitors / centrifugal switch.

Les.

You would be looking to see if there are any wires or links on the back of the board. For example terminal K only has a white wire from the run capacitor so unless there is something is connected to K on the underside of the board the run capacitor is not serving any purpose. IF Noel's suspicion that the centrifugal switch has changeover contacts is correct and the NO contact is connected to terminal K then the run capacitor would be connected in series with the run winding when the motor was up to speed. (Which is how it should be in circuit when the motor is up to speed.) I have only ever seen centrifugal switches which connect the start capacitor in parallel with the run capacitor until the motor is up to speed. Most motor are easy to take apart. There is normally 4 threaded rods holding the end plates together. There may also be bearing retainer plates that are held in place with two screws close to the bearing housings. The bearing will probably remain on the shaft when an end plate is removed. Take care to note the position of any springy washers that might be in the bearing housing.

Les.

Hi Keith,
The NVR switch in the picture is not suitable for the way I suggested wring it. This is because both ends of the coil are directly connected to the output. In this NVR switch on ebay there is a picture showing that one end of the coil winding is brought out to a separate terminal. (Marked A1) Any NVR which with one end of the coil brought out to it's own terminal can be used. It looks like there is no direct connection between K and AZ. The way your meter behaved is what I would expect when it is effectively connected to a capacitor. (In this case the run capacitor..I think the only way to confirm that the centrifugal switch is not the changeover type that Noel suspects is to partly dismantle the motor.

Les.

Hi Keith,
Noel makes a good point about terminal K being connected to the NO contact of a changeover centrifugal switch. (Although I have never seen one that method would work.) I think it would be a good idea to dismantle the motor to see if there are two or three wires going to the centrifugal switch. You could also check if there was anything connected to the terminals on the underside of the terminal board.

Les.

Keith,
Now all the wires are re connected to the terminals can you measure the resistance between terminal K and terminal AZ. (You will initially get a lowish reading (Due to the capacitors.) but it is the steady reading I am interested in. This is to try to understand why the run capacitor did not seem to be connected and also see if the number of conductors between the motor and the reversing switch can be reduced from 5 (+ earth) to 4 (+earth).

Les.

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.