Brook Crompton motor terminals?

[julianf]

I have a single phase motor here, which is wired up and working, but i need to reverse the direction. Which is no big deal, and can be done by swapping the start cap terminals.

...however, my motor has additional terminals in the box, which dont appear on others, and i want to work out what they are before changing stuff.

My motor has an identical board to this one (photo off the internet) but mine has terminals where the "K" and "S" are marked in the photo -

Anyone recognise this, and able to enlighten me?

The A / AZ are, i believe, the run terminals
The Z / T are the start
The K / S are.... (?)



On my unit, from what i could see with a torch last night, the box is as follows -

K - nothing

AZ -
red (blue stripe) to housing
green to cap
black to housing

S -
blue to housing
red (black stripe) to housing

A -
neutral
blue to housing
red to housing

Z -
green to cap
blue to housing
yellow to housing

T -
purple to housing
live

(by 'housing' i mean into the body of the motor, out of sight, rather than to the housing itself)

The motor has two caps, one is wired through the side of the terminal box (which is why i can see the wires) but one goes into the motor body (and then, i assume, back out to the terminal box, but i cant see which wires are which)


note, the motor is from my rapidor saw

 

[Wendelspanswick]

Two speed motor?

 

[Spark plug]

Not sure off the top of my head,

This may help you figure it out

 

[oilyneil]

Here you go;
http://www.instructables.com/id/Wiring-up-a-Brooke-Crompton-single-phase-lathe-mot/

 

[julianf]

I have seen the instructables links (indeed, the photo in my first post was pulled from one of them : ) but...

a) i have a load of extra wires
b) the only visible cap connection on mine is to the Z and AZ terminals, which does not make sense against the information in the links (which state run windings are AZ and A, and the start are Z and T)

What im wondering is -

The motor runs currently.
I can only see the wires from one of the caps (the other is wired through the motor housing, and i cant even see the colours of the wires)

So -

Is it just the polarity of one cap against the other that determines the direction?

If so, could i just leave everything as is, except for the one cap that i can see, and reverse that one (not knowing if its the start or the run, and not understanding why its connected as it is currently!)?

 

[Spark plug]

I have reversed some single phase motors in the past simply by removeing the rotor turning it 180deg. It's usually quicker than trying to figure the wireing out.

 

[eil]

I would be more inclined to swap polarity on the run winding, I suspect that could be black on AZ with red on A, would check with a multi meter first though.

 

[julianf]

To update my initial post, i missed out a cable (purple) connected to the AZ termainal.

Updated list -

K - nothing

AZ - (instructables suggests run) - suggested live
red (blue stripe)
green to visible cap
black
purple

S -
blue
red (black stripe)

A - (instructables suggests run) - suggested neutral
neutral
blue
red

Z - (instructables suggests start) - suggested neutral
green to visible cap
blue
yellow

T - (instructables suggests start) - suggested live
purple
live

 

[julianf]

One thing that i really dont understand -

I assume there is nothing going on on the back of the board / terminals (ie out of sight) and that all the connections are to the top side.

If this is the case, then, for example, the T terminal - that's doing nothing, other than joining the live from the mains cable to a purple cable.

This seems like a redundant move - why not just connect the mains live direct to where ever the purple cable goes?

Mains live is required at the run cap, the run winding and either the start cap or the centrifugal switch

...so, my thinking is that the purple may be a jumper to AZ.

But that's where my logical reasoning breaks up!

Im not at the same location as the unit at present, so no multimeter testing just yet.

 

[eil]

A pic of yours would be better I can see where your run cap is, but where is the start cap.

 

[julianf]

This is the most useful (useless) photo i have currently -

You can see that the smaller of the two caps on the top of the motor is wired into the motor housing itself, whilst the larger of the two enters the terminal box right on (off) the edge of the photo.

Its the larger of the two caps that has the green wires, connected to Z and A

I dont have a photo of the inside of the terminal housing, but it wouldnt tell you a lot anyhow. Ive had to hook wires around with a rod just to see whats what in there. A photo would just show a mess of wires!

 

[eil]

Anyone ever said that you are special Julian, you might have a special motor as well , go to section 12 page 185
http://chiclassiccomp.org/docs/content/books/TheModelEngineersHandbook_TubalCain.pdf

 

[julianf]

Thank you!

Even the 'special' is not exactly what i have, as the K terminal is used in the document, whilst the T is redundant.

...however, the directions for virtually all of the units are identical - to swap the blue and yellow.


Mine has only one yellow, but a few blue wires.


As the yellow on mine is wired to the Z terminal, im looking at the only motors in the PDF that also wire the yellow to the Z

Fortunately, the two units that wire the yellow to Z also wire the blue to A.

So, as my motor has a blue to A, i think its a fair assumption that this is the wire to go for!

Ill try this out on Sunday, and report back - thank you very much for your help!

 

[eil]

Or as I said in post 7 swap the red and black might be easier, it doesn't make no difference which winding you change over so long as its only one.

 

[julianf]

Or as I said in post 7 swap the red and black might be easier, it doesn't make no difference which winding you change over so long as its only one.

I was where the motor is, yesterday -

my intention was to swap the yellow and blue wires, as per my previous post, but when I checked the length of the wires in the terminal box, it was much easier to swap the red and the black, as advised by "eil" all those posts ago...

The motor now runs in the opposite direction, with no issues, and the saw that its attached to (the rapidor) now stays in gear perfectly.

Thank you to all who took the effort to reply to this thread, and, especially eil, for the solution and the interesting pdf!