Whadda ya think?

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rattus

Senior Member
Dem funny little squiggly lines ya see in da schoolroom scopey thingey.:p

JK....:) I am bored.

Sines and cosines of course.

Join the fray if you are bored.

Oops! Answered the wrong post, but any post in a storm!
 
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jim dungar

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Please define what you are refering to as "waves."
This is most likely coming from the 2000+ thread about single phase. The discussion there is about a very specific situation of a single voltage waveform and its inverse waveform.
 

__dan

Banned
Is there any difference in the criteria for waves to be 'of the same phase' and 'in phase'?

A car rolls forward and both front tires rotate in the same direction. Now place yourself between the front tires as the car rolls forward and turn your head 180 deg to look at each tire. Looking to the left, the driver's side tire rotates clockwise. Looking to the right, the pasenger side tire rotates counterclockwise.

Seeing the tires rotate in two different directions, is it your conclusion that there is a difference ? If your answer is yes, then, well, you could say yes to anything. If your answer is no, you have somehow dispute the information provided by your own eyes to satisfy your own inquiry.

If you are unable to at some point in the future resolve your dilemma, perhaps your smart friend could convey an understanding that provides comfort and relief from this uncertainty.
 

rattus

Senior Member
Opinion:

Opinion:

In the absence of any disagreement, I will venture to say the criteria are the same, That is, the frequency must of course be the same, and then, considering only the sinusoids, if they are 'in phase' or 'of the same phase', the curves must follow the same locus--they overlie each other.

Then, 'in phase' and 'of the same phase' mean the same thing. Or in other words, their phase constants (phase angles) must be the same provided that both waves are either sines or cosines.
 

rattus

Senior Member
A car rolls forward and both front tires rotate in the same direction. Now place yourself between the front tires as the car rolls forward and turn your head 180 deg to look at each tire. Looking to the left, the driver's side tire rotates clockwise. Looking to the right, the pasenger side tire rotates counterclockwise.

Seeing the tires rotate in two different directions, is it your conclusion that there is a difference ? If your answer is yes, then, well, you could say yes to anything. If your answer is no, you have somehow dispute the information provided by your own eyes to satisfy your own inquiry.

If you are unable to at some point in the future resolve your dilemma, perhaps your smart friend could convey an understanding that provides comfort and relief from this uncertainty.

Is that a yes or a no?
 

__dan

Banned
Is that a yes or a no?

Yes there is a difference. Same phase is a naming convention. To be in phase, the phases would have to be within an allowable window for paralleling or transfer at a closed transiition switch, voltage and phase angle difference matching within allowable tolerances. You could have two phases named the same but having a wide range of conditions unaceptable for paralleling or closing to the same bus.
 

mivey

Senior Member
Actually just bought a set of these. I was offered whitewall or blackwall by reversing the tire. I asked if the orientation made a difference to the tire and was told "no, they are phase invariant".

http://www.michelinman.com/tire-selector/name/ltx-m-s2-tires
The ones I linked are direction sensitive. When you rotate the tires you have to do a front-back or have them re-mounted.

If you take the cross product of the axle vector produced by the tire rotation with the vector of vehicle motion, they do not point in the same direction. There really is a physical difference between the left and right side tire.
 

rattus

Senior Member
Yes there is a difference. Same phase is a naming convention. To be in phase, the phases would have to be within an allowable window for paralleling or transfer at a closed transiition switch, voltage and phase angle difference matching within allowable tolerances. You could have two phases named the same but having a wide range of conditions unaceptable for paralleling or closing to the same bus.

What if the two waves carried EXACTLY the same phase angle?

Would they be in phase?

Would they be of the same phase?
 

__dan

Banned
What if the two waves carried EXACTLY the same phase angle?

Would they be in phase?

Would they be of the same phase?

I don't have the dictionary definition for you. My purpose in using the terms would be to convey information and avoid confusion, in a practical or practicing sense.

Having the same phase is a naming convention, they are both 'A' phase. They could be or likely to be derived from seperate systems and paralleling them could or would be inadvisable.

Being in phase, in a practical sense the equipment provides paralleling or closed transition switching capacity and it is time to throw the switch. Will it work or will it go boom. Should it go boom but work accidentially (I see both). Matching phase angle is not enough, voltage must match as well as current rating of the equipment for the connected load. That is beyond the conventional definition of in phase.

It go boom, saying they are the same phase will not cut it.
 

rattus

Senior Member
I don't have the dictionary definition for you. My purpose in using the terms would be to convey information and avoid confusion, in a practical or practicing sense.

Having the same phase is a naming convention, they are both 'A' phase. They could be or likely to be derived from seperate systems and paralleling them could or would be inadvisable.

Being in phase, in a practical sense the equipment provides paralleling or closed transition switching capacity and it is time to throw the switch. Will it work or will it go boom. Should it go boom but work accidentially (I see both). Matching phase angle is not enough, voltage must match as well as current rating of the equipment for the connected load. That is beyond the conventional definition of in phase.

It go boom, saying they are the same phase will not cut it.

The questions do not mention amplitude, only phase. It didn't ask about paralleling either. I will take your answer to mean maybe.
 
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