Transmission line ruling span calculation

[simatic7]

Hi Everybody
I just want to know when calculating the ruling span in transmission line we use the formula
Ruling span=sqrt((sum of each span cube)/(total span))
between the dead end structure. I am confused with the term dean end structure. Can any one explain to me what is the meaning of dead end structure.

1 is it the structure with tension insulators of turning (breaking) angle of more than 60 degree on both towers at the both end OR

2. Is the the structure just adjacent to substation as the line connects two substation.

3. while calculating the ruling span , the total length of the line to be considered is the length of line between two substation or between two towers of breaking angle of more than 60 deg or 90 deg ?

4. can there be more than one ruling span for a transmission line design in one section of transmission line between two substation
Thanks in advance for your kind and sincere answers
regards
Simatic7

 

[alehman]

dead end = point where all of the horizontal tension is transferred to a structure.

There can be many dead ends in a line - not just at substations. e.g. riser pole, double-guyed or 90 degree turn. Turns where tension is transferred around the corner (e.g. single-point insulators) are not a dead end.

Suggest consulting an experienced engineer.

Alan
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