The old field has 17 turns on each field. For a total of 34 turns for two

poles.

These two fields were wired in parallel. When you say "work out the total

amp turns"

Is that amp/turns per pole?

Since the two poles are is parallel that would be 1/2 times amp/turns or

(.5

x amps)/17turns

And, what wiring scheme should I use: all in series, all in parallel,

parallel

two and put in series with the other parallel two?

Thanks for your input, MikeK

Your reply is confusing, firstly you said you had a compound motor so

there should be two windings on each pole, series and shunt, you now

seem to have only one.

I'll try again.

I have a compound 4 pole motor. Two of the poles are series fields with

17 turns, these two are wired in parallel. The other two poles are shunt

fields

and wound with many (100s) of turns. These are wired in series.

Each pole has only one winding on it.

Secondly poles come in pairs, so a four pole

motor has 2 pole pairs, opposite each other.

This is correct.

Each pole pair needs to be considered as independent from the other

pole pair. Magneticaly the poles of a pair are in series so the amp turns

add up. eg: 17 turns at 1amp for each pole equals 34amp turns in total.

But, these are in parallel so the current is divided, that would make it,

1/2amp x 17turns x 2 poles = 17 amp-turns.

I think?

Someone on a forum suggested that shunt fields commonly have equal amp-turns

as the series field, so winding the new series fields the same as the

original would

give similar torque and rpm.

So, if I wire the two new 17 turn poles in parallel and put those in series

with

original two 17 turn parallel poles I should have 1/2 amp through each pole

of

17 turns, this equals 8.5 amp-turns. With 4 poles x 8.5 amp-turns I would

end

up with 34 amp-turns. I think this would be equal to the original series and

shunt fields as far as amp-turns.

What do you think?

Thanks, MikeK