Reversing Motor

The 2 you can not see are Z(top left) S is to the right of Z

Z S

K AZ A

Hi Keith, assuming that A, B, and C on your forward/reverse switch are the common connections, I believe the schematic below should work, but you will need to disconnect both the yellow and blue wires from the posts and bring connections A, Z, yellow and blue out to your forward/reverse switch, you may need to swop yellow and blue to suite the switch.

Regards Nick.

Thank you Nick I will try that, but I had swapped blue and yellow in the motor and popped the trip. I will let you know how it goes

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.

Hi Keith, I do agree with Les though, you ought to check out the motor as he has said, or get it checked, before you go to the trouble of wiring the forward/reverse switch, otherwise you'll not know why if it's still tripping.

I have also updated the schematic which should also work and you should be able to use a single 6 core flex from your switch to the motor, one of the 6 cores would be an earth, but failing that you would need at least a 5 core flex, or you could use a flexible conduit and use single wires.

Regards Nick.

Edited By Nicholas Farr on 05/02/2021 11:02:23

The motor runs fine in the original yellow blue position(anti-clockwise) and no problem running the lathe.

Results after oms test and could only find 3 pairs that gave readings + the s - k terminal reading

Blue/Yellow 9.4

Grey/Red 2.7

Purple/Red with black stripe 0.4

S and K 0

Many thanks

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.

Nick clarke had a similar problem with trying to reverse a cap start, cap run motor ! With the help of his pictures I think I may have the answer. The centrifugal switch is a change over switch. This perplext me ! but the circuit diagram shown earlier I THINK makes it all clear. Black and red (run ) are across L1 & N, Purple goes to the moving contact on the centrifugal switch. Red/black is N/C contact and K is the N/O contact. On change over the start capacitor is taken out of circuit and the run capacitor connected. So to reverse it is blue and purple that need to be swapped ? I will give it more thought !! Noel

Another post on here this afternoon also indicates that it is the purple wire that need to be swapped. N

In the photo of the switch are the wires running  between A & B insulated ? If not there is part of the problem.

Edited By noel shelley on 06/02/2021 14:42:45

Edited By noel shelley on 06/02/2021 14:56:23

Noel

Did you not see the makers advice and details on the terminal cover plate stating to reverse the motor interchange Blue and Yellow wires ?

Emgee

Emgee, yes ! but if the switch is is to be used as both reversing and running then it appears less simple. The switch shown would reverse a 3ph motor but not so sure about 1ph. Noel.

A bit more info after Les kindly gave some instructions.

2 x White from K & Z go to cap 10uf +/- 5% 425v

2 x Red with black a stipe from Z & S go to cap 120/150 uf 230v

Continuity test between:
Purple wire and Red wire with a black stripe that disappears behind board, none when switch is pushed open manually.
Blue and Yellow.
Red and Black.

No continuity between any terminals including K & S.

I could not spin the motor today.

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

Never seen a capacitor start capacitor run motor with a change over switch. On the ones I've worked on, on start up both caps are in parallel and in series with the start winding. When up to about 75% of max speed the centrifugal switch which on start up was closed, now OPENS, leaving the smaller value capacitor in circuit with the start winding. and in parallel with the run winding. Keith, your 120/150 is the start capacitor (with a short time rating) and the the 10 is the run one. I'll read more tomorrow, . John

I also had never seen a change over switch until Nick clarkes. The centrifugal switch had a wire crimped to the moving contact terminal, the normally closed cotact had a male spade and the normally open contact is K. Noel

Edited By noel shelley on 06/02/2021 18:10:59

Hi Les,

When you refer to the switch is this the centrifugal switch and you managed to operate it manually -
Yes i used a thin screwdriver to operate it.
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 ?
Its open circuit
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.)

Terminal wire colours as they were originally, no swapping as follows:

K - White
AZ - Purple, Red, Red(Mains supply)
A - Yellow, Black, Black(Neutral mains supply)
Z - Blue, white, Red with black stripe
S - Red with black stripe, Red with black stripe

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.

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

This is my revised diagram.

Les.

Hi Les,

I only have a ohms/continuity tester.

The picture of the connection box was taken before swapping, once swopped it tripped but once put back in the original positions Yellow on A and Blue on Z the motor ran fine again(anti-clock).

If there was a short would the motor still run as well as it does?

Many thanks

Edited By Keith Jenkins 1 on 07/02/2021 12:10:23

I know the experts do not agree with me and have never seen one, nor had I until a few weeks ago. At that point I could not fathom out how it worked. The motor in question had the run capacitor missing and the wiring all took out. Only the makers wiring diagram gave the game away as I had seen the centrifugal switch out of the motor.

The run windings red and black are on A and AZ. The start windings are on A and Z. The missing terminal T if fitted would be for the thermal over heat.. Purple on AZ is the common or moving contact on the centrifugal switch. Red/black on S is the normally closed contact and K is the normally open contact ! There will be NO connection between K and S as has been shown. Start cap is Z and S, run cap is Z and K. L1 is AZ and N is A. A simple proof of concept would be to wire as shown above and note the direction of rotation and then swap blue and yellow and again see if the motor direction has reversed. You now know if the motor is still good. It is not uncommon on older motors for them to fail when reversed due to insulation coming off the connecting wires and going to ground. Careful use of sleeving can effect a repair.

Since awhile ago it was considered by some that in offering advice like this I was putting life at risk I must point out - YOU ARE DEALING WITH LEATHAL VOLTAGES, if you are not sure what you are doing - DON'T DO IT ! Noel.