So in the coffee bar this morning chat pondered on 3-phase and how to
know which of the 3 wires was which phase. I've done some googling
and would like the experts to confirm:

1. It doesn't matter which wire is which phase providing the sequence
of 1-2-3 2-3-1 or 3-1-2 is maintained when connecting, or any pair
swapped if that is what is required.

2. The voltage between any two phases is 440v and it doesn't matter
which two

and

3. The voltage between any phase and ground/neutral is 240v

Is that correct?

Are there any conditions when the phase needs to be known? If so how
is it detected?




--
AnthonyL

Why do scientists need to BELIEVE in anything?

In article ,
AnthonyL wrote:
So in the coffee bar this morning chat pondered on 3-phase and how to
know which of the 3 wires was which phase. I've done some googling
and would like the experts to confirm:

1. It doesn't matter which wire is which phase providing the sequence
of 1-2-3 2-3-1 or 3-1-2 is maintained when connecting, or any pair
swapped if that is what is required.

2. The voltage between any two phases is 440v and it doesn't matter
which two

and

3. The voltage between any phase and ground/neutral is 240v

Is that correct?

Are there any conditions when the phase needs to be known? If so how
is it detected?

when connecting up a 3 phase gennerating plant to the grid. Can't
remember, I never became a poer engineer.

--
from KT24 in Surrey, England
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle

AnthonyL wrote:

So in the coffee bar this morning chat pondered on 3-phase and how to
know which of the 3 wires was which phase. I've done some googling
and would like the experts to confirm:

1. It doesn't matter which wire is which phase providing the sequence
of 1-2-3 2-3-1 or 3-1-2 is maintained when connecting, or any pair
swapped if that is what is required.

2. The voltage between any two phases is 440v and it doesn't matter
which two

and

3. The voltage between any phase and ground/neutral is 240v

Is that correct?

Are there any conditions when the phase needs to be known? If so how
is it detected?

Totally ignorant comment he

Surely there is no absolute phase (in power distribution at least), just
phase in relation to the other two phases. So no real life equipment
could know the difference as long as you can swap any two if it is
wrong.

Is it good practice in real life to keep the same colour wires
throughout the whole installation for each incoming phase?

--

Roger Hayter

On 01/03/2020 13:37, AnthonyL wrote:
So in the coffee bar this morning chat pondered on 3-phase and how to
know which of the 3 wires was which phase. I've done some googling
and would like the experts to confirm:

1. It doesn't matter which wire is which phase providing the sequence
of 1-2-3 2-3-1 or 3-1-2 is maintained when connecting, or any pair
swapped if that is what is required.

2. The voltage between any two phases is 440v and it doesn't matter
which two

and

3. The voltage between any phase and ground/neutral is 240v

Is that correct?


Yes

Are there any conditions when the phase needs to be known? If so how
is it detected?





As long as you know the 1-2-3, 2-3-1 or 3-1-2 rotation you should be OK.



--
Adam

charles wrote:

In article ,
AnthonyL wrote:
So in the coffee bar this morning chat pondered on 3-phase and how to
know which of the 3 wires was which phase. I've done some googling
and would like the experts to confirm:

1. It doesn't matter which wire is which phase providing the sequence
of 1-2-3 2-3-1 or 3-1-2 is maintained when connecting, or any pair
swapped if that is what is required.

2. The voltage between any two phases is 440v and it doesn't matter
which two

and

3. The voltage between any phase and ground/neutral is 240v

Is that correct?

Are there any conditions when the phase needs to be known? If so how
is it detected?

when connecting up a 3 phase gennerating plant to the grid. Can't
remember, I never became a poer engineer.

As long as they were in the right order wouldn't they just slip into
sync?

--

Roger Hayter

Jethro_uk wrote:

On Sun, 01 Mar 2020 13:37:47 +0000, AnthonyL wrote:

Are there any conditions when the phase needs to be known? If so how is
it detected?

If you connect a 3-phase motor up wrong, it won't work. Does that count ?

From a position of no theoretical knowledge and little practical
experience, I thought it would go backwards. Am I wrong?




This has the suggestion of leading to a bridges of Koenigsberg puzzle ...
what's the minimum number of wires you'd need to swap to get it
working


--

Roger Hayter

On Sun, 1 Mar 2020 14:12:25 +0000, Roger Hayter wrote:

Jethro_uk wrote:

On Sun, 01 Mar 2020 13:37:47 +0000, AnthonyL wrote:

Are there any conditions when the phase needs to be known? If so how is
it detected?

If you connect a 3-phase motor up wrong, it won't work. Does that count ?

From a position of no theoretical knowledge and little practical
experience, I thought it would go backwards. Am I wrong?

The motors at work did - switch on, look at the fan or feel the airflow,
sod's law...
Can't remember (30 years ago) what happened with the 3-phase fridge motors.
The condensr fan might have been the indication, but it might have been
single phase.
We had a 3-phase USP but that was just for providing 3-off 1-phase supplies.

--
Peter.
The gods will stay away
whilst religions hold sway

On Sunday, 1 March 2020 14:12:27 UTC, Roger Hayter wrote:
Jethro_uk wrote:

On Sun, 01 Mar 2020 13:37:47 +0000, AnthonyL wrote:

Are there any conditions when the phase needs to be known? If so how is
it detected?

If you connect a 3-phase motor up wrong, it won't work. Does that count ?

From a position of no theoretical knowledge and little practical
experience, I thought it would go backwards. Am I wrong?




This has the suggestion of leading to a bridges of Koenigsberg puzzle ...
what's the minimum number of wires you'd need to swap to get it
working



It depends.
A 3ph motor can be connected in "star" or " delta/mesh" (Mesh=USA)
Reversing any two phases reverse the motor.

However if you swop the connections on one of the windings, (ie reverse the Live and Neutral connections,) it won't run.

On 01/03/2020 13:37, AnthonyL wrote:
So in the coffee bar this morning chat pondered on 3-phase and how to
know which of the 3 wires was which phase. I've done some googling
and would like the experts to confirm:

1. It doesn't matter which wire is which phase providing the sequence
of 1-2-3 2-3-1 or 3-1-2 is maintained when connecting, or any pair
swapped if that is what is required.

2. The voltage between any two phases is 440v and it doesn't matter
which two

400v +10% - 6%

and

3. The voltage between any phase and ground/neutral is 240v

230v +10% -6%.

Are there any conditions when the phase needs to be known? If so how
is it detected?


--
Colin Bignell

On 01/03/2020 13:37, AnthonyL wrote:
So in the coffee bar this morning chat pondered on 3-phase and how to
know which of the 3 wires was which phase. I've done some googling
and would like the experts to confirm:

1. It doesn't matter which wire is which phase providing the sequence
of 1-2-3 2-3-1 or 3-1-2 is maintained when connecting, or any pair
swapped if that is what is required.

2. The voltage between any two phases is 440v and it doesn't matter
which two

and

3. The voltage between any phase and ground/neutral is 240v

Is that correct?

yes


Are there any conditions when the phase needs to be known? If so how
is it detected?

The only time you need to know is when connecting to a true AC motor
when reversing any two phases will reverse the motor direction






--
Future generations will wonder in bemused amazement that the early
twenty-first centurys developed world went into hysterical panic over a
globally average temperature increase of a few tenths of a degree, and,
on the basis of gross exaggerations of highly uncertain computer
projections combined into implausible chains of inference, proceeded to
contemplate a rollback of the industrial age.

Richard Lindzen

On 01/03/2020 14:01, Roger Hayter wrote:
Totally ignorant comment he

Surely there is no absolute phase (in power distribution at least), just
phase in relation to the other two phases. So no real life equipment
could know the difference as long as you can swap any two if it is
wrong.

yes.

Is it good practice in real life to keep the same colour wires
throughout the whole installation for each incoming phase?
yes.


--
Future generations will wonder in bemused amazement that the early
twenty-first centurys developed world went into hysterical panic over a
globally average temperature increase of a few tenths of a degree, and,
on the basis of gross exaggerations of highly uncertain computer
projections combined into implausible chains of inference, proceeded to
contemplate a rollback of the industrial age.

Richard Lindzen

On 01/03/2020 14:08, Jethro_uk wrote:
On Sun, 01 Mar 2020 13:37:47 +0000, AnthonyL wrote:

Are there any conditions when the phase needs to be known? If so how is
it detected?

If you connect a 3-phase motor up wrong, it won't work. Does that count ?

This has the suggestion of leading to a bridges of Koenigsberg puzzle ...
what's the minimum number of wires you'd need to swap to get it
working

one pair


--
Future generations will wonder in bemused amazement that the early
twenty-first centurys developed world went into hysterical panic over a
globally average temperature increase of a few tenths of a degree, and,
on the basis of gross exaggerations of highly uncertain computer
projections combined into implausible chains of inference, proceeded to
contemplate a rollback of the industrial age.

Richard Lindzen

On 01/03/2020 14:12, Roger Hayter wrote:
Jethro_uk wrote:

On Sun, 01 Mar 2020 13:37:47 +0000, AnthonyL wrote:

Are there any conditions when the phase needs to be known? If so how is
it detected?

If you connect a 3-phase motor up wrong, it won't work. Does that count ?

From a position of no theoretical knowledge and little practical
experience, I thought it would go backwards. Am I wrong?





depends if its CAPABLE of going backwards


--
€œThose who can make you believe absurdities, can make you commit
atrocities.€�

€• Voltaire, Questions sur les Miracles Ã* M. Claparede, Professeur de
Théologie Ã* Genève, par un Proposant: Ou Extrait de Diverses Lettres de
M. de Voltaire

It matters quite a bit if you close an interconnector without the two sections being synchronised.

Would it not confuse a motor though?
Brian

--
----- --
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"Roger Hayter" wrote in message
...
charles wrote:

In article ,
AnthonyL wrote:
So in the coffee bar this morning chat pondered on 3-phase and how to
know which of the 3 wires was which phase. I've done some googling
and would like the experts to confirm:

1. It doesn't matter which wire is which phase providing the sequence
of 1-2-3 2-3-1 or 3-1-2 is maintained when connecting, or any pair
swapped if that is what is required.

2. The voltage between any two phases is 440v and it doesn't matter
which two

and

3. The voltage between any phase and ground/neutral is 240v

Is that correct?

Are there any conditions when the phase needs to be known? If so how
is it detected?

when connecting up a 3 phase gennerating plant to the grid. Can't
remember, I never became a poer engineer.

As long as they were in the right order wouldn't they just slip into
sync?

--

Roger Hayter

In message , ARW
writes
On 01/03/2020 13:37, AnthonyL wrote:
So in the coffee bar this morning chat pondered on 3-phase and how to
know which of the 3 wires was which phase. I've done some googling
and would like the experts to confirm:
1. It doesn't matter which wire is which phase providing the
sequence
of 1-2-3 2-3-1 or 3-1-2 is maintained when connecting, or any pair
swapped if that is what is required.
2. The voltage between any two phases is 440v and it doesn't matter
which two
and
3. The voltage between any phase and ground/neutral is 240v
Is that correct?


Yes

Are there any conditions when the phase needs to be known? If so how
is it detected?


As long as you know the 1-2-3, 2-3-1 or 3-1-2 rotation you should be OK.

Synchronising a generator?

--
Tim Lamb

On Sun, 1 Mar 2020 17:59:00 +0000, The Natural Philosopher
wrote:

On 01/03/2020 13:37, AnthonyL wrote:
So in the coffee bar this morning chat pondered on 3-phase and how to
know which of the 3 wires was which phase. I've done some googling
and would like the experts to confirm:

1. It doesn't matter which wire is which phase providing the sequence
of 1-2-3 2-3-1 or 3-1-2 is maintained when connecting, or any pair
swapped if that is what is required.

2. The voltage between any two phases is 440v and it doesn't matter
which two

and

3. The voltage between any phase and ground/neutral is 240v

Is that correct?

yes


Are there any conditions when the phase needs to be known? If so how
is it detected?

The only time you need to know is when connecting to a true AC motor
when reversing any two phases will reverse the motor direction


What about when it's being connected to the grid?

--
AnthonyL

Why do scientists need to BELIEVE in anything?

On Sunday, 1 March 2020 20:10:43 UTC, Cynic wrote:
It matters quite a bit if you close an interconnector without the two sections being synchronised.

All you need is three lamps.

Eg:-

https://www.nuclear-power.net/nuclea...oscope-method/

On Mon, 02 Mar 2020 00:37:10 -0800, harry wrote:

On Sunday, 1 March 2020 20:10:43 UTC, Cynic wrote:
It matters quite a bit if you close an interconnector without the two
sections being synchronised.

All you need is three lamps.

Eg:-

https://www.nuclear-power.net/nuclea...ysics/reactor-
operation/reactor-startup/synchronizing-lamps-synchroscope-method/

I remember reading of a case where the lamps were wired incorrectly. On
the first attempt to sync, there was an expensive bang.



--
My posts are my copyright and if @diy_forums or Home Owners' Hub
wish to copy them they can pay me £1 a message.
Use the BIG mirror service in the UK: http://www.mirrorservice.org
*lightning surge protection* - a w_tom conductor

AnthonyL laid this down on his screen :
1. It doesn't matter which wire is which phase providing the sequence
of 1-2-3 2-3-1 or 3-1-2 is maintained when connecting, or any pair
swapped if that is what is required.

Yes. Which is which phase will normally be decided and checked at the
incomer (with the instrument I). The phase marking will then be
maintained throughout the installation. If a 3ph motor is already
marked for the correct phases to ensure the correct direction of
rotation, if connected with the correctly marked phases, it will run
the desired way. Swapping over any two of the three phase wires, will
reverse the direction of rotation.


2. The voltage between any two phases is 440v and it doesn't matter
which two

Yes.

3. The voltage between any phase and ground/neutral is 240v

Yes.

Are there any conditions when the phase needs to be known? If so how
is it detected?

There is no way to determine on an unmarked 3ph cable, which wire is
which phase apart from the obvious belling method of comparing the
voltage to the known incoming other end. To ensure, or check correct
phase rotation, engineers use a tiny 3ph handheld (I), three wire
motor.

On Mon, 2 Mar 2020 00:37:10 -0800 (PST), harry
wrote:

On Sunday, 1 March 2020 20:10:43 UTC, Cynic wrote:
It matters quite a bit if you close an interconnector without the two sections being synchronised.

All you need is three lamps.

Eg:-

https://www.nuclear-power.net/nuclea...oscope-method/

Lamps were last used in anger in the 1980's, where there was still some
generation connected at distribution voltages

Syncroscopes were always used for synchronisation at main generation sites. You
still had a single check light but the pointer showed the rate of slip relative
to the grid

But both methods are wholly reliant on the skill of the operator and the speed
of breaker closure, get it wrong and you can very easily wreck the generator
rotor.

Everything (as in post 1987 ish in the UK ) is now done electronically such that
it is impossible to synch incorrectly, even with a total system split and a
large disparity on phase rotation rates and voltages. You prime the breaker
with the appropriate sync mode and just wait, for up to 30 mins if necessary at
which point it will time out.

Generation just runs the governor against the reference voltage and frequency
and autocloses within preset voltage and slip parameters. The level of operator
skill required is near zero.







--

On Sun, 1 Mar 2020 12:10:41 -0800 (PST), Cynic wrote:

It matters quite a bit if you close an interconnector without the two sections being synchronised.

All interconnectors with the exception of the one from Lancashire to the Isle of
Man are DC and as such there is no concept of synchronisation.

Coupling sections of busbar or overheads is also in the main performed with both
ends in synchronisation because the system is always operated as one frequency
zone.


If a system split happens or there is a phase shift due to reactive components
then the breaker is closed under an automated procedure but only when the rate
and magnitude of the vectors are within preset parameters.
--

In article ,
Jethro_uk wrote:
Are there any conditions when the phase needs to be known? If so how
is it detected?

If you connect a 3-phase motor up wrong, it won't work. Does that count ?

They generally just run in reverse.

--
*If you try to fail and succeed, which have you done? *

Dave Plowman London SW
To e-mail, change noise into sound.