TWO PHASE MOTOR

[SUNRAY]

Let's get back to OP.

Chances are this is a 2 phase motor,
Chances are the N terminal is a functional N terminal,
Chances are P1 requires one of the phases to be connected to it,
Chances are P2 requires a different phase to be connected to it.

IF the above is correct and I emphasise IF, the second phase is derived from the same 230V supply as P1 by adding a series capacitor to provide a phase shift.
IF all of the above is correct, reversing the connexions to P1 & P2 the motor will run in the oposite direction.

Most of the reversible motors I have got involved with (a very small sample) they have worked on some sort of version off this description.

As there are so many variations on the way single phase motors are built it is quite easy for this post to be totally irrelevant in the case of the OP's motor.

 

[JohnW2]

Let's get back to OP. .... Chances are this is a 2 phase motor,...

Forgive my ignorance (I've never had much to do with anything other than very simple motors), but is there actually such a thing as a "2-phase motor"?

Kind Regards, John

 

[SUNRAY]

Forgive my ignorance (I've never had much to do with anything other than very simple motors), but is there actually such a thing as a "2-phase motor"?

Kind Regards, John

I would imagine that most motors which require a capacitor come into the category.

 

[JohnW2]

I would imagine that most motors which require a capacitor come into the category.

I would have thought that all motors I've come across which require a capacitor have been 'single-phase' (by any sensible definition), not "2-phase".

Kind Regards, John

 

[winston1]

Chances are this is a 2 phase motor,

No way. US supplies are 240v centre tapped at 120v. Standard US wire colours are black for A side (L1), red for B side (L2), and white for neutral. For 240v loads the white should not be connected unless it is a parking terminal.

Chances are the N terminal is a functional N terminal,

No, see above.

Chances are P1 requires one of the phases to be connected to it,
Chances are P2 requires a different phase to be connected to it.

Well yes, but they are not really different phases, they are A and B of a centre tapped supply.
To use it here P1 and P2 must be connected to L and N.

IF the above is correct and I emphasise IF,

It isn't. The wire colours give it away.

 

[SUNRAY]

No way. US supplies are 240v centre tapped at 120v. Standard US wire colours are black for A side (L1), red for B side (L2), and white for neutral. For 240v loads the white should not be connected unless it is a parking terminal.



No, see above.



Well yes, but they are not really different phases, they are A and B of a centre tapped supply.
To use it here P1 and P2 must be connected to L and N.



It isn't. The wire colours give it away.

So in this grand scheme of yours of correcting others, Where is the capacitor? and What does it do?

 

[winston1]

So in this grand scheme of yours of correcting others, Where is the capacitor? and What does it do?

From your very first post:

"but this particular example had a 15uF start cap in series with one winding."

 

[bernardgreen]

but is there actually such a thing as a "2-phase motor"?

I would imagine that most motors which require a capacitor come into the category.

The capacitor and the second winding create a pseudo phase of current in the second winding which is a few degrees out of phase with the current in the first winding. These two out of phase currents create a "rotating" magnetic field that rotates the rotor in the required direction.

There are two phases in the motor but only one phase is supplied to the motor. The motor, via it's capacitor, creates its own internal second ( pseudo ) phase.

 

[SUNRAY]

From your very first post:

"but this particular example had a 15uF start cap in series with one winding."

Aaaahhh so this motor has more than one winding???


So the motor has how many functional terminals?
And how many 'dummy' terminals?

 

[SUNRAY]

.

 

[SUNRAY]

No way. US supplies are 240v centre tapped at 120v. Standard US wire colours are black for A side (L1), red for B side (L2), and white for neutral. For 240v loads the white should not be connected unless it is a parking terminal.



No, see above.



Well yes, but they are not really different phases, they are A and B of a centre tapped supply.
To use it here P1 and P2 must be connected to L and N.

Unless I have misunderstood the posts in this thread so far, this particular motor has 3 terminals:
N, P1 & P2

'N' has a whte wire connected to. This appears to have been ASSUMED to be the neutral wire and has been described as a dummy (isolated terminal solely for 'parking' a redundant wire).
one of the 'P's has a black wire connected to it. This appears to have been ASSUMED to be the hot connexion.

the other 'P' has a capacitor 'wired in series'

Now pardon my ignorance but how is this motor supposed to operate?

It isn't. The wire colours give it away.

Oh and I learnt a very long time ago not to assume the colour of the wires inside a piece of eqipment have any relevance other than the manufacturers design, which does not have to comply with wiring regs in this country and I assume this is also the case elsewhere in the world.



I realise I am referring/replying to more than one poster.

 

[bernardgreen]

 

[SUNRAY]

View attachment 162433

I don't understand the possible orange connection in this sketch unless it's a dual voltage motor, in which case I'd expect 5 or 6 windings terminals + 2 cap terminals,then there'd be no reason for the dummy terminal. I know they frequently are but Ididn't think the capacitor is built into this particular motor!

From OP's description I get the impression he is not overly familiar with this sort of thing and is asking for advice (this is not in any way a critisism), therefore with the reference to capacitor in series with one winding - My interpretation of the information given so far is this:

with an external capacitor
Which I have taken to be this:

and developed it into this:

which matches your 'UK' diagram electrically.

Further to my assumptions so far:
I assume this machine has been functional in the UK until now but developed a fault and therefore wherever the neutral wire is CURRENTLY CONNECTED is the correct position for it to work in the UK.
Working on that basis:
and assuming the white wire is indeed the neutral wire
and assuming that the terminal labelled 'N' is indeed the functional neutral terminal
then I assume my drawings are more likely to be the case.

I have made a lot of assumptions, based on experience and the brief descriptions from OP. As always an OP photo and more replies could remove a lot of the guesswork and hopefully provide him with the knowledge he seeks.

I have certainly found this to be correct in the small number of ocassions that I've been involved in this type of motor.
I've not knowingly come across the dummy terminal situation.

Winston, Bernard and possibly others, by the sound of things have had different experiences to me which I have no doubt are perfectly valid and in this case have made different assumptions to me.

 

[JohnW2]

The capacitor and the second winding create a pseudo phase of current in the second winding which is a few degrees out of phase with the current in the first winding. These two out of phase currents create a "rotating" magnetic field that rotates the rotor in the required direction. There are two phases in the motor but only one phase is supplied to the motor. The motor, via it's capacitor, creates its own internal second ( pseudo ) phase.

Yes, I understand that, but it is only relevant when there are two windings.

It seems like this maybe a case of "one learns something every day"! Are you saying that all the "two-wire" motors I've seen actually have two windings and, in many cases, a 'hidden' start capacitor?

Kind Regards, John

 

[SUNRAY]

Yes, I understand that, but it is only relevant when there are two windings.

It seems like this maybe a case of "one learns something every day"! Are you saying that all the "two-wire" motors I've seen actually have two windings and, in many cases, a 'hidden' start capacitor?

Kind Regards, John

No they don't all use a capacitor, but as a general rule (which has become less relevant over the years) powerful non-com motor have had a cap - or other device to create a phase change.