RUS Bulletin 1724E-200

[stevenal]

Says to add two bells for dead-ends, but fails to indicate why. It goes on to speak of leakage distance, explaining the horizontal strings wash better and are less susceptible to contamination leakage, so this does explain the difference. Does anyone know why to add bells at dead-ends, and does this translate to additional length, leakage, and/or BIL when selecting polymer suspension insulators? Thanks.

 

[jghrist]

Lightning acts like a travelling wave on a transmission line which increases in magnitude when it reaches a higher impedance like a deadend. Adding bells at deadends increases the BIL. See

https://eepower.com/technical-artic...ween-lightning-and-power-transmission-lines/#

 

[stevenal]

Thanks. From your link:

A tower represents a discontinuity to the traveling waves of current and voltage circulating through the ground wires, whereby these waves are reflected and refracted.

Eepower does not appear to make a distinction between tangent and dead-end structures here. ??

I should note that RUS says to add a bell for angle structures, where conductor tension pulls the insulators away from the structure.