Catenary Cables

The Precise Method of Sagging Overhead Transmission Conductors

INSTRUCTIONS:

• On project profile, sketch a tangent line from setup location to the conductor and ensure the point of tangency is within the middle third of the span

• Setup instrument parallel with conductors, and ideally, position it directly underneath the attached point (Zero Offset)

  • • A negative offset must be used if setup location is outside of the span

    • If setup is inside the span, use a positive offset

• Collect the necessary data:

  • • Span Length

    • Elevation difference between attachments

    • Conductor Unit Weight ( lb/ft or kg/m)

    • Transverse Offset

    • Longitudinal Offset

    • Height from Transit to Attachment

    • Wire Temperature

    • Designed horizontal tension at the current wire temperature

    • Measured zenith angle (if checking existing wire sag)

• Input the necessary information into either form and select "Calculate" to view the result

  • • "Sag Wire" is used during construction to precisely place each conductor at the designed mid-span sag & horizontal tension

    • "Check Sag" is used to verify the sag accuracy of each conductor after construction is complete

• If using a dynamometer, the indicated tensions correspond to a solitary span with deadends on either end. Refrain from utilizing these tensions to sag multiple spans simultaneously

  • • For optimal results, position the dynamometer at the higher elevation structure

    • Ensuring the dynamometer is well-maintained, calibrated, and correctly employed is essential for obtaining precise measurements