V-String Swing Angle Derivation, Design Considerations, and Structure Design Impacts

The use of V-string insulator hardware assemblies has been utilized on transmission line structures for their control of conductor position, clearance to supporting structure, and structural advantage. In designing V-strings, a critical design criterion consideration is insulator leg compression. Specifically, the weather (wind) condition that induces V-string insulator compression impacts the V-string interior angle, arm lengths, drop bracket length, pole shaft diameter, and foundation reactions. This paper provides insight into V-string analysis methodology and comparisons of different conductors, wind loadings, wind and weight span ratio limits, and V-string internal angle configurations. Wind loading effects on insulator leg compression are specifically examined for multiple weather cases ranging from 4 to 21 psf. Also examined is the inefficiency of a set parameter design (line angle range, conductor type, wind and weight span, etc.) compared to the potential design envelope, which can be utilized with design software such as Power Line Systems PLS-CADD.