C & Z Value

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Okay maybe I am overthinking this.

C is also used for Capaitance and Celsius.

If it is C as in figuring Xc for Z, then see note 2, table 9. Xc is not used in the table calcs.

If it is C as in using a different temperature (usually denoted as T) than 75C, then see note 2, table 8.
 
jumper said:
Anyone ever feel like you are talking to yourself?:D
Click to expand...
My dear wife does it all the time..........
Maybe the OP will explain what C he is referring to.
For voltage drop one would normally refer to R and Z.
But what would I know - I'm just thick according to..................you know who.
 
Besoeker said:
My dear wife does it all the time..........
Maybe the OP will explain what C he is referring to.
For voltage drop one would normally refer to R and Z.
But what would I know - I'm just thick according to..................you know who.
Click to expand...
"If I wanted your opinion, dear, I would have told you what it is."

Sent from my XT1585 using Tapatalk
 
C-value attached

C-value attached

What does the c-value mean here
Area of a conductor, circular mils ???

see attached
Thank you
Ed:happysad:
 

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  • 3 PH Isc+V.D-3.pdf
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Toros said:
What does the c-value mean here
Area of a conductor, circular mils ???

see attached
Thank you
Ed:happysad:
Click to expand...

That chart is not VD.The bottom one is.

No, C there is some constant (non-changing variable) used for a short circuit calculation, Isc.

I have no clue what it stands for or how it is derived. It is not total circular mils however.

That is an EE level calc for the most part, I have never did it.

Here is a good link with math and charts if you are interested.

http://www.cooperindustries.com/con...rary/BUS_Ele_Tech_Lib_Electrical_Formulas.pdf
 
Ingenieur said:
not an issue
now answering is another matter
Click to expand...

I do that from time to time when working through a problem. Had a supervisor who sat in the cubicle on the other side of the "wall" from me quip, "Talking to yourself again?" Un-sotte voce I replied "absent-mindedly", "Sometimes it's the only way I can have an intelligent conversation around here." Our executive admin heard the whole exchange and collapsed in hysterical laughter when I followed that by saying all innocent-like: "Did I say that out loud?"
 
TOROS
Refer to page 6 of 10 on LINK provided by "JUMPER".

C - constant values used in the Point-to-Point calculation method.
PDF has ALL the formulas used depending on 3P-1P-etc.
Keep a copy, you can put the formulas into a spreadsheet and calc your own results as needed.

The VD drop calcs on the PDF you provided I believe are incorrect.
Listing a Z value from Chap 9-Table 9, which is calculated at PF=0.85.
Formula on PDF seems to be adding another factor of 0.8...not sure where this is coming from.

Z values in your PDF tables are NOT the Z values from NEC except for the #4/0.
 
Did anyone else notice that they spelled “fault” incorrectly on that chart? My brain can’t avoid seeing things like that, sometimes I get tired of it because I get stuck on it.
 
Jraef said:
Did anyone else notice that they spelled “fault” incorrectly on that chart? My brain can’t avoid seeing things like that, sometimes I get tired of it because I get stuck on it.
Click to expand...
A lot of that happens. Here and elsewhere. It irks me too (or two or to) but I try to let it go under the radar as long as the intended meaning is clear. There are bigger things to worry about.
 
MyCleveland said:
TOROS
Refer to page 6 of 10 on LINK provided by "JUMPER".

C - constant values used in the Point-to-Point calculation method.
PDF has ALL the formulas used depending on 3P-1P-etc.
Keep a copy, you can put the formulas into a spreadsheet and calc your own results as needed.

The VD drop calcs on the PDF you provided I believe are incorrect.
Listing a Z value from Chap 9-Table 9, which is calculated at PF=0.85.
Formula on PDF seems to be adding another factor of 0.8...not sure where this is coming from.

Z values in your PDF tables are NOT the Z values from NEC except for the #4/0.
Click to expand...
thank you,
just corrected
 
jumper said:
That chart is not VD.The bottom one is.

No, C there is some constant (non-changing variable) used for a short circuit calculation, Isc.

I have no clue what it stands for or how it is derived. It is not total circular mils however.

That is an EE level calc for the most part, I have never did it.

Here is a good link with math and charts if you are interested.

http://www.cooperindustries.com/con...rary/BUS_Ele_Tech_Lib_Electrical_Formulas.pdf
Click to expand...


imho that method is confusing and more complicated than necessary
just do a single line with the Z for each xfmr/wire segment
can be modified from infinite bus to util supplied values by reflecting util Z to sec
easy to make an excel spreadsheet
 
Ingenieur said:
imho that method is confusing and more complicated than necessary
just do a single line with the Z for each xfmr/wire segment
can be modified from infinite bus to util supplied values by reflecting util Z to sec
easy to make an excel spreadsheet
Click to expand...

It may be, I cannot say either way.

While the actual math is pretty basic, IME it has always been an EE or Senior EC who performs it. I have never been asked to do it.

I can say that from experience that screwing up and installing 10k equipment when 22k stuff should have been speced cost my boss a pretty penny to replace a pile of discos and panels and such.
 
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