Why is residential wiring known as single phase?

[K8MHZ]

Hmmmm, I always thought of it as the ratio between the long and short side of a triangle with a 120 degree angle

It's that, too.

I just applied it so a person in the field could use a voltmeter and a calculator and simple math and see the relationship.

I like simple math.

 

[Joethemechanic]

It's that, too.

I just applied it so a person in the field could use a voltmeter and a calculator and simple math and see the relationship.

I like simple math.

The year before I quit high school I was a "MATHALETE" I even got a letter for on my sweater. :happyyes:

Chicks dig that yaano

 

[gar]

120130-1237 EST

1732 is George Washington's birth year.

Draw a right triangle with one side equal to 1/2 the hypotenuse. Use the pythagorean theorem to determine the other side. What is its value? Multiple this by 2. What is that value? How can you geometrically prove that exactly 1/2 is the sine of 30 deg?

You will also find that

cos x = 1 - x²/2! + x⁴/4! - ............ etc to infinity.

The infinite series for sin is similar

sin x = x - x³/3! + x⁵/5! ............

where x is in radians, 2*Pi radians = 360 deg.

1 radian is about 57.30 deg, and 30 deg is about 0.524 radians, so

cos (0.524) = 1 - 0.1371 + 0.00313 = 0.86605 a more accurate value is 0.866025404 from HP 32S.
This infinite series converges very quickly.

.

 

[Besoeker]

If it is 180 degree apart,current in the neutral would be double.

If they were in phase the neutral current double assume the same load on both windings. And you wouldn't have 240V end to end.

The more usual arrangement:

 

[K8MHZ]

The year before I quit high school I was a "MATHALETE" I even got a letter for on my sweater. :happyyes:

Chicks dig that yaano

I hated math but excelled at it. I found it tedious, boring and not much more than mental masturbation. I did as much as I could in my head (and was REALLY good at it) and got chastised by the teachers for doing so. I never studied, did little homework, and aced the tests, resulting in a C grade. That drove my teachers crazy.

I remember sitting in those damned math classes staring out the window and hearing my name being called by my motorcycle.

"Ride me....ride me, Marky"

I remember being in the very first advanced math classes in junior high school. One of the teachers had this game called 'Equations' which she loved. In fact, she loved it so much that she signed up her brightest students to go to the U of M for an Equations competition.

I got chosen. So did three geeky girls. I hated the game. They loved it. I had to ride from Muskegon to Ann Arbor and back with two women teachers and three geeky girls, plus bear an absolutely insufferable math game in the process.

Ah....those were the days.

 

[K8MHZ]

120130-1237 EST

1732 is George Washington's birth year.

Draw a right triangle with one side equal to 1/2 the hypotenuse. Use the pythagorean theorem to determine the other side. What is its value? Multiple this by 2. What is that value? How can you geometrically prove that exactly 1/2 is the sine of 30 deg?

You will also find that

cos x = 1 - x²/2! + x⁴/4! - ............ etc to infinity.

The infinite series for sin is similar

sin x = x - x³/3! + x⁵/5! ............

where x is in radians, 2*Pi radians = 360 deg.

1 radian is about 57.30 deg, and 30 deg is about 0.524 radians, so

cos (0.524) = 1 - 0.1371 + 0.00313 = 0.86605 a more accurate value is 0.866025404 from HP 32S.
This infinite series converges very quickly.

.

Gar, I like you and all, but sometimes you sound like Dr. Sheldon Cooper when you try to explain things.

 

[Besoeker]

f you looked at all three voltages on a scope, you would only see two waves, as the two 120 volt waves would be superimposed upon each other.

Not so if you used neutral as the reference point - not an unreasonable thing to do - you'd see what I presented in post #31.

 

[K8MHZ]

Not so if you used neutral as the reference point - not an unreasonable thing to do - you'd see what I presented in post #31.

That's fine....but how do you use the N for a reference if you are measuring voltage from one hot to another? No problem using it for the 120 volt measurements.

If you checked the voltage from N to either hot, using N as a reference (black lead of a volt meter and leaving it there) at the exact instance in time one hot peaked positive, so would the other. Also at that exact time, the voltage between the two hots would peak positive.

So, if the two 120 volt waves peak positive at the exact same time, how would they not be superimposed? In order to get a mirror image, you would have to swap leads, and swapping leads means the reference point is now changed.

Also, if the O-scope did indicate two wave forms, mirror imaged, which side of the 0 line would the 240 volt wave form be, the top or the bottom?

 

[K8MHZ]

Not so if you used neutral as the reference point - not an unreasonable thing to do - you'd see what I presented in post #31.

I just went back and looked at the wave forms.

According to your graph, -170 and +170 volts occur at the exact same time. How does that not equate to a net sum of 0? If it does, then why do our meters not read 0 when we connect them from hot to hot?

 

[jim dungar]

If they were in phase the neutral current double assume the same load on both windings. And you wouldn't have 240V end to end.

Try again ,so far all you have shown is that you can change the way the windings are interconnected. You went from a parallel connection to a series connection and then said see there is a difference.

You are showing the voltages combine to make a larger value, and the currents combine to make a smaller value. How did the voltages and the currents change phase with each other?

 

[david luchini]

We are talking about open voltages, not closed loops, and the relationship I am illustrating is not KVL.

So what happens when we close the loop by putting a load on it? The voltage angles magically change?

Remember, we are summing voltages and getting a positive number as a result, not 0. The fact that the two 120 volt legs add up to 240 volts instead of 0 does not violate KVL.

For your open circuit you are violating basic vector math. The voltages have not only magnitude, but also direction.

Vector math, and

Vab = Van + Vnb = Van - Vbn

 

[gar]

120130-1537 EST

I did not comment on phases before because that discussion will get nowhere. There already was one very long thread on the subject. Different groups have different definitions. So there has to be a willingness to view the subject from different perspectives.

.

 

[K8MHZ]

120130-1537 EST

I did not comment on phases before because that discussion will get nowhere. There already was one very long thread on the subject. Different groups have different definitions. So there has to be a willingness to view the subject from different perspectives.

.

Or different.....angles.

 

[K8MHZ]

So what happens when we close the loop by putting a load on it? The voltage angles magically change?

Of course not, but putting a load on it does not create an additional phase.

"Remember, we are summing voltages and getting a positive number as a result, not 0. The fact that the two 120 volt legs add up to 240 volts instead of 0 does not violate KVL."

For your open circuit you are violating basic vector math. The voltages have not only magnitude, but also direction.

If I measure, with a meter, 240 volts from one hot to the other and 120 volts from either hot to N, how does that violate basic vector math?

 

[Besoeker]

If you checked the voltage from N to either hot, using N as a reference (black lead of a volt meter and leaving it there) at the exact instance in time one hot peaked positive, so would the other.

It wouldn't. Not wrt neutral and that seems to be the point your are missing.

 

[Joethemechanic]

I remember sitting in those damned math classes staring out the window and hearing my name being called by my motorcycle.

"Ride me....ride me, Marky"

In my case it was a black 1970 ish Yamaha 650 twin. that bike lasted forever

 

[Besoeker]

According to your graph, -170 and +170 volts occur at the exact same time. How does that not equate to a net sum of 0?

If it did equate to zero you wouldn't measure 240V end to end.
But you do.
It's potential difference, not potential sum that you measure.
The -170 and +170 gives you 340V peak potential difference.
Which, coincidentally or otherwise, is 240V_rms. Not zero.

 

[david luchini]

Of course not, but putting a load on it does not create an additional phase.

Of course it doesn't create an additional phase, we're talking about a single phase system. Not sure I understand the point.

If I measure, with a meter, 240 volts from one hot to the other and 120 volts from either hot to N, how does that violate basic vector math?

I think its pretty clear that if you measure the magnitude and angle and measure the voltages from one hot to the other, we'd get a result that had the same magnitude for each measurement, but a voltage angle that was 180 degrees different for each measurement.

For example, Vab=240<0 and Vba=240<180.

Now lets measure from A to the neutral, I think we'd see 120<0. (And if we measured from Neutral to B, 120<0)
And from B to the neutral, I think we'd see 120<180 (And if we measured from Neutral to A, 120<180).

Adding Van+Vbn would give zero volts. Adding Vna+Vnb would give zero volts.

Adding Van+Vnb would give 240<0 volts, and adding Vbn+Vna would give 240<180 volts.

In other words...Vna=-Vnb, just as Vab=-Vba.

 

[K8MHZ]

Of course it doesn't create an additional phase, we're talking about a single phase system. Not sure I understand the point.

The point is we are talking about a single phase system and I am not sure I understand the point you don't understand....:slaphead:

 

[david luchini]

The point is we are talking about a single phase system and I am not sure I understand the point you don't understand....:slaphead:

I don't understand why you are talking about "creating an additional phase." Where does that come from?:?