Brook motor problem.

[Les Jones 1Participant @lesjones1]

Hi Mark,
From those tests it looks like you had it connected up correctly. When you open the motor to get at the switch check the insulation around the switch for signs of burning or deposits of vaporized metal from large sparks.

Les.

[Mark P.Participant @markp]

Thanks for your help Les, and everyone else much appreciated.

Mark P.

[Mark P.Participant @markp]

Last question. The capacitor goes in series with the switch ie. Live to one side of the capacitor then to.the switch and then off to the start winding?
Mark P.

[EmgeeParticipant @emgee]

Possibly best live to the switch – switch output -capacitor -start winding.

Emgee

[Mark P.Participant @markp]

I'm still having trouble getting my head round the connections. The capacitor is connected to terminals Z and S, the red and green wires which means that it would not be connected in the start circuit. As you can see from the photo when things are connected as per negative to Z and A, Live to AZ the capacitor is not connected to the switch. Am I missing something fundamental? I feel that the capacitor should be in series with the switch,not connected across Z and S. Would this account for the yellow flash and the tripping of the RCD?

Mark P.

[VicParticipant @vic]

With only a live, neutral and earth on a single phase cable why would a manufacturer put five or six terminals on a motor? Just asking!

[Nick_GParticipant @nick_g]

Posted by Vic on 17/08/2014 13:58:04:

With only a live, neutral and earth on a single phase cable why would a manufacturer put five or six terminals on a motor? Just asking!

So that the single phase motor can be reversed if required.

There is a bit more to it than with a 3 phase motor.

Nick

[Keith LongParticipant @keithlong89920]

Vic

Motors are made for universal application – to be as versatile as possible. If the motor has to be able to run in both directions under switch control then the start and run windings need to come to separate terminals so that connections can be made independently. So with run and start windings – that's 4 terminals; if the centrifugal switch is brought out to the terminal plate that will be 2 more and you might find a terminal post to anchor the earth to as well.

[john fletcher 1Participant @johnfletcher1]

The start winding will have the highest resistance, much higher than the run winding which should be around 4 ohms. As some one has already stated, the start winding, the capacitor, together with the centrifugal switch form a series winding, which are then connected in parallel with run winding. Once the motor is up and running the centrifugal switch opens, leaving just the run winding connected to the mains electricity. If the capacitor is connected to terminals Z & S Ok, As I see from your picture(photo) one side of the centrifugal switch is also connected to terminal S OK there. So, from terminal S to the lower Lucar connection on the Bakelite centrifugal switch board, through the switch, checking that the contacts are clean and that they do close up, then to the upper Lucar connection, that forms the start circuit. At this stage you should, using a multi meter on the ohms range, be able to measure the start winding circuit resistance. Its not easy to test the capacitor as they are special AC electrolytic, not the ordinary paper type although they will be OK.

It would appear that you need two short links one between Z & AZ, the other between A & T. The mains is connected to A & AZ either way round. To reverse the motor move T to AZ and Z to A. The most important wire is the EARTH. SO ENSURE YOU HAVE A GOOD CLEAN EARTH CONNECTION, and if your motor is mounted on resilient rubber mounts check there is a link between the base mounting plate and the motor the motor casing. Let me know how you get on.Ted

[CotswoldsPhilParticipant @cotswoldsphil]

Hi Mark P,

I have today just swapped stators between two Crompton and Parkinson motors, one of which has an intermittent connection – it kicks when shocked, the other had worn bearings so making 1 good one out of two.

I'm looking at the wiring label inside the motor terminal box –

Z – Blue (or Yellow depending on rotation) motor wire + Green/Red from capacitor

AZ – Red + Maroon + Yellow (or Blue depending on rotation) motor wires

A – Black motor wire + Green/Red capacitor – This is the Neutral Connection

T – Maroon motor wire – This is the Live Connection

Don't forget the earth tucked in the corner of the connection box on the end case.

To change the direction of rotation – swap the Yellow and Blue wires on Z and AZ

My motors, are both working (one a lot faulty) each one in opposite directions, with the wiring shown above. I did have some difficulty confirming which was the blue wire (on AZ) because the colour has faded somewhat in the 40 odd years since manufacturer. In the end, I decided that the third wire was quite different from the Red and Maroon connected to the AZ terminal and must be the blue one.

Hope this might help

Regards

Phil H

[CotswoldsPhilParticipant @cotswoldsphil]

Hi Again,

Just reviewed the post and need to add that the Maroon wires are in fact for a thermal cutout fitted to the motors I am working on – so this may be the link that is being talked about.

Regards

Phil H

[Mark P.Participant @markp]

Thanks chaps, I think I can see what is going on. On a different tack anyone know anything about an Evershed and Vignoles 250V Megga?

Mark P.

[Les Jones 1Participant @lesjones1]

Hi Mark and others,
When I first looked at the picture posted today I first thought there were two yellow wires coming out of the bottom of the winding. This confused me but on closer inspection it is a link between the bottom connection of the centrifugal switch and terminal "T" This is my understanding of the start winding connections. Starting at terminal "Z" This is connected to one side of the capacitor, The other side of the capacitor is connected to the blue end of the start winding at terminal "S" The yellow end of the start winding is connected to the top end of the centrifugal switch with the push on connector. The bottom connector on the centrifugal switch is connected to terminal "T" via the yellow wire. This means that the thee items are in series between terminals "T" and terminal "Z" (Note it does not matter the sequence that these the items are connected in series.) This means that the way Mark described his connections in his first message are correct. Looking at the way the collar on the shaft operates the centrifugal switch makes me wonder if the switch and the collar have been assembled in the correct relationship.It looks like the white ring on the collar is an insulating ring which should operate the switch. I cannot remember if the collar moves up or down when the motor is up to speed. Is it possible that it moves up and the metal part touches the switch (Shorting it to earth) rather than the switch being actuated by the insulated part ? Testing the motor with an external switch to simulate the action of the centrifugal switch would show if this is the case. (Note BOTH wires to the centrifugal switch must be removed to do this test.

Les.

[CotswoldsPhilParticipant @cotswoldsphil]

Hi Mark and others,

I've worked up a hand-drawn schematic for the motors I've been working on, it's in my albums and reproduced here. The maroon wires are connecting a resettable overload cut-out on my motors. The centrifugal switch may be on the other side of the capacitor, it's also closed when stopped. Black and Red are run winding Yellow and Blue start winding. AZ is the common terminal.

Hopefully it illuminates your problem. It's a bit manic spider but …..

Regards

Phil H

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