Strained conductors · Sag & Tension Tool

Short-circuit currents – Mechanical effects

Calculate how the conductor moves and how much force it experiences during and after a short circuit, including effects on sag and spacing, using temperature extremes and choosing the worst-case results for safe design.

Strained conductors arrangement (SS-EN 60865-1)

Rigid conductors (SS-EN 60865-1)

Placeholder figure. Replace with a diagram/image later.

IEC TR 60865-2:2015, Example 4 — side elevation (above) and plan view (below) for twin slack conductors between supports. Enter span l, phase spacing, and electrical quantities below.

With effective span input, l_eff is the reduced span used in the report for bundle pinch and swing-out checks when that mode is selected.

When phase distance uses the average of inner and outer pair distances, set a₁ and a₂ to match the conductor staggering shown in the plan view at each tower.

IEC TR 60865-2:2015, Example 5 — arrangement with strained conductors: side elevation (above) and plan view (below). — IEC TR 60865-2:2015, Example 5 — side elevation (above) and plan view (below). Enter geometry below; cord length l_c follows l − 2 l_i.
In the span there are two connections of pantograph-disconnectors, which also operate as spacers, and between the connections one spacer.
When sub-spans along l_c are equal: centre-line span l_s = l_c / (n_c + 1). Else l_s is the maximum existing centre-line distance between two adjacent connecting pieces.

IEC TR 60865-2:2015, Example 6 — side elevation (above) and plan view (below) for strained conductors with a mid-span dropper. Enter span, dropper geometry, and electrical inputs below.

Parallel vs perpendicular drop geometry follows the selected plane; cord length and width define the dropper path used with the main bundle in SS-EN 60865-1 clearance models.

Warm and cold result cards use the same I″_k, duration, and bundle mechanical defaults as in IEC TR 60865-2 unless you override them in the form.

Mechanical

Sub-conductor lineSubconductors per phase n

Number of spacers n_c

Bare subconductor mass per unit length m′_s [kg/m]

Number of end connections n_conn

Mass of one connection m_c [kg]

Mass of one spacer m_cs [kg]

Spring constant S (both supports) [N/mm]

Sub-conductor outer diameter d [mm], SS-EN 60865-1 §6.4

Subconductor metal area [mm²]

Stranded Young modulus E [MPa]

Thermal expansion coefficient c_th [m⁴/(A²·s)]

Geometry

Phase distance inputPhase distance a [m]

Span length inputSpan length l [m]

Insulator chain length l_i [m]

Cord l_c used in SS-EN 60865-1: 37.40 m

Subconductor centre-line spacing a_s [m]

Connecting-piece centre-line span l_s [m]

Electrical excitation

κ sourceInitial symmetrical short-circuit current I″_k [kA]

Short-circuit duration T_k1 [s]

System frequency f [Hz]

R/X at fault (IEC 60909 context)

Cold / warm static tensile forces

Static tensile force F_st (cold) [kN]

Static tensile force F_st (warm) [kN]

ResultsWarm conductor

Short-circuit tensile force

F_t,d

32.63 kN(§6.2.3)

Drop (bundle) force

F_f,d

69.00 kN(§6.2.6)

Pinch force

F_π,d

69.44 kN(§6.4.2)

Maximum swing-out

δ_max

91.4 °(§6.2.2)

Maximum horizontal span displacement

b_h

1.48 m(§6.2.7)

Minimum air clearance

a_min

2.03 m(§6.2.7)

ResultsCold conductor

Short-circuit tensile force

F_t,d

35.95 kN(§6.2.3)

Drop (bundle) force

F_f,d

67.06 kN(§6.2.6)

Pinch force

F_π,d

72.60 kN(§6.4.2)

Maximum swing-out

δ_max

95.2 °(§6.2.2)

Maximum horizontal span displacement

b_h

1.35 m(§6.2.7)

Minimum air clearance

a_min

2.30 m(§6.2.7)

Design summarySS-EN 60865-1

Pinch force at cold conductor

Posts, supports, foundations (rating 1,0)

72.60 kN(§6.5.1)

Pinch force at cold conductor

Structures, insulator chains, connectors

72.60 kN(§6.5.2)

Maximum horizontal span displacement

warm conductor

1.48 m(§6.2.7)

Minimum air clearance

warm conductor

2.03 m(§6.2.7)

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Short-circuit currents – Mechanical effects