2 Phases of a 3 Phase System

[Ingenieur]

Real slow - I haven't had my second cup yet: How are you measuring this V? GD tg and others are correct, one needs a reference to measure a voltage.

no one said you did not
we are talking about phase
a signal does not need a reference to have a phase attribute
in fact it exists without measurement

 

[GoldDigger]

no one said you did not
we are talking about phase
a signal does not need a reference to have a phase attribute
in fact it exists without measurement

Without a reference it is not a signal. :happysad:

 

[Ingenieur]

Without a reference it is not a signal. :happysad:

sure it is
just because you don't have a meter on it doesn't mean it isn't there
before and after amp clamping the I is the same
the 'reference' is a mathematical convention
:happyyes:

 

[GoldDigger]

sure it is
just because you don't have a meter on it doesn't mean it isn't there
before and after amp clamping the I is the same
the 'reference' is a mathematical convention
:happyyes:

Current does not need a reference. It is measured at a cross section in a conductor.
Voltage does not exist without a reference.
Voltage as a potential field from which an electric field can be derived can be said to exist in the absence of any measurement, but the specification of that field, like the value of an indefinite integral, contains an arbitrary additive constant.
To get a unique voltage measurement you must specify two points in the field.
I do not see any value in trying to convince you of this, so I am bowing out unless other contributors have anything interesting to add.

 

[Ingenieur]

Current does not need a reference. It is measured at a cross section in a conductor.
Voltage does not exist without a reference.
Voltage as a potential field from which an electric field can be derived can be said to exist in the absence of any measurement, but the specification of that field, like the value of an indefinite integral, contains an arbitrary additive constant.
To get a unique voltage measurement you must specify two points in the field.
I do not see any value in trying to convince you of this, so I am bowing out unless other contributors have anything interesting to add.

Current has a reference
coloumbs/sec, so time is the reference
or integrate the magnetic field in a closed loop around the current
so that path is reference

how does a 'stinger' work?
can an electric field be measured in point space?
but I digress, it was said phase needs a reference
it does not, it is a unique and independent property

this should have been post 2

it's not called 2 phase because it is NOT 2 phases
it is one single phase
why doesn't matter
lol


peace
lighten up folks
all in fun

 

[GoldDigger]

...can an electric field be measured in point space?

Yes, but a voltage cannot. Only voltage differences.

The electric field is defined in terms of the force on an electric charge occupying that point in space and can be sufficiently well approximated for our purposes using the force on an electron centered at that point in space.

 

[Ingenieur]

Yes, but a voltage cannot. Only voltage differences.

The electric field is defined in terms of the force on an electric charge occupying that point in space and can be sufficiently well approximated for our purposes using the force on an electron centered at that point in space.

so yes
potential can be measured across the field
2 point measurements not required to be taken simultaneously


but again the statement was made that phase can only be measured with 2 signals
a subject and reference
not true
a single signal possesses magnitude and phase

 

[ActionDave]

Y'all are overthinking this. Not uncommon here, threads like this usually have about 300+ posts with no agreement. ....

I have been curiously watching this one to see if it starts to snowball. Still has potential.

 

[Ingenieur]

I have been curiously watching this one to see if it starts to snowball. Still has potential.

This 'snowball' of which you speak
does it need a reference to determine phase?
or does it possess electric potential or 'voltage' at a single point proportional to
electric potential energy / charge... Units (joules/coulomb = volts)
????
does it have a chance in h@!! ?

mmmm snowballs
View attachment 14439

 

[jumper]

I have been curiously watching this one to see if it starts to snowball. Still has potential.

Notice that OP never chimed back in.

 

[ggunn]

Notice that OP never chimed back in.

Can you blame him?

 

[iceworm]

so yes
potential can be measured across the field
2 point measurements not required to be taken simultaneously


but again the statement was made that phase can only be measured with 2 signals
a subject and reference
not true
a single signal possesses magnitude and phase

Slower please. Had several cups - doesn't seem to be helping. Still having trouble with this concept of V-I phase angle having only one wire - i.e., no reference.

Here is an example of the kind of thing that is bothering me:
Say one has two ungrounded, isolated, 3 phase deltas connected by a tie breaker. They both come from the same source, so you know there are in phase, but you want to verify that a phase hasn't been rolled before closing the first time. And in this case every thing was connected correctly - you just don't know that yet. So you measure across the tie CB, A-A, B-B, C-C. Should all measure zero V, right? Nope. Don't know. No reference. Could be anything thing.

Yes I know it is not the same thing. I'm suffering imminent brain implosion trying to get wrapped around measuring a voltage or voltage angle with out a reference. I'm likely just not understanding what you are trying to do. So reeaaallll sslllloooooowwww. What are you telling us?

 

[Ingenieur]

V metering between common (or believed) to be common phases is a check
https://electricalnotes.wordpress.com/2012/07/17/parallel-operation-of-transformers/

• Synchronizing should be checked of both the supply voltages. This can be checked directly with millimeter between L1 phases of Transformer 1 and L1 phase of Transformer 2. Then L2 Phase of Transformer 1 and L2 Phase of Transformer 2. Then L3 Phase of Transformer 1 and L3 Phase of Transformer 2. In all the cases MultiMate should show 0 voltages theoretically. These checks must be done at synchronizing breakers only.

Best way to check synchronization on LT is charge complete panel with 1 source up to outgoing terminals of another incoming breaker terminal. Then just measure Voltage difference on incoming and outgoing terminals of Incoming Breaker. It should be near to 0.

I'm not talking about measuring the 'phase'
whether between i and v of the same phase leg
or the relative difference between phases, ie, 0, 120, -120

what I am saying is the phase is an attribute of the signal
like magnitude
independent of any other signal

line currents
when a 3 ph setup sees unequal reactive Z's each phase suffers a different phase shift
independent
just like line current magnitude can be different depending on load

the bottom line a 3 ph L-L in not called '2 phase' because it is a single phase

 

[kwired]

Notice that OP never chimed back in.

Most anyone that has ever asked the question the OP did gets explanations way beyond their comprehension and don't know what to ask to help with what they want to understand on a somewhat simpler level.

It has been asked before sometimes in different ways but basically "what is a phase?" and with all the minds that participate here there is no single consensus on that definition that I can recall ever seeing.

 

[Smart $]

If you ask me (I realize no one has :lol, the topic has shifted from 'conventional' to 'esoteric'.

Please include the word system in all future communiques. :happyyes:

 

[iceworm]

...Best way to check synchronization on LT is charge complete panel with 1 source up to outgoing terminals of another incoming breaker terminal. Then just measure Voltage difference on incoming and outgoing terminals of Incoming Breaker. It should be near to 0 ...

Ing -
Doesn't appear you read my post. In the case I listed, no - No reference between the two. The voltage is indeterminate.

... the bottom line a 3 ph L-L in not called '2 phase' because it is a single phase ...

As others already said, yes. Two wires, it's single phase. You got that part right.

Enough for me. Have a good day. Back to work for me.

ice

 

[ggunn]

Most anyone that has ever asked the question the OP did gets explanations way beyond their comprehension and don't know what to ask to help with what they want to understand on a somewhat simpler level.

There's also the fact that many questions asked in here touch off a series of assertions and challenges that drifts off into Never Never Land.

 

[Ingenieur]

Ing -
Doesn't appear you read my post. In the case I listed, no - No reference between the two. The voltage is indeterminate.

As others already said, yes. Two wires, it's single phase. You got that part right.

Enough for me. Have a good day. Back to work for me.

ice

It will give you an indication if phased properly
0 is still a voltage 480/0 - 480/0 and is determinate, both are the same or in phase
if it were 480/0 + 480/120 you would have 480/60
got it all right: phase is a property of a signal and does not need reference

back to sloughing off
Out of town all week for training at a federal academy
get some and give some

 

[ggunn]

It will give you an indication if phased properly
0 is still a voltage 480/0 - 480/0 and is determinate, both are the same or in phase
if it were 480/0 + 480/120 you would have 480/60
got it all right: phase is a property of a signal and does not need reference

back to sloughing off
Out of town all week for training at a federal academy
get some and give some

“He would've had you by now, Captain, if he hadn't swallowed that alarm clock. But now, when he's about, he'd warn you, as you might say, with his tick-tock, tick-tock, tick-tock.”―Mr. Smee

 

[Sahib]

The phase of a phase, whether it be current or voltage is measured with reference to time. So time is the reference for the phase of a phase. Got it?