Next generation of hinge mounted insulating crossarms

A detailed motion analysis of the insulating cross-arms—covering stability and behaviour under broken-wire conditions—showed that, under extreme mechanical loading, the resulting displacements can lead to collisions with the underlying tower structure. Consequently, increased self-stabilisation and improved clearance to the tower were recommended to prevent mechanical interference during the rotation of pivoting horizontal V-arms. Non-pivoting cross-arms

In line with modern engineering practice, we adopted a probabilistic design approach focused on resilience and maintainability. Replacing an insulating arm can typically be completed within one day, whereas replacement of the underlying lattice structure can require several months.

This optimisation—together with the selected clamp configuration—enabled the development of a tension solution integrated into the insulating arms, thereby allowing the conception of a quasi-full overhead line based on insulating cross-arms. Furthermore, because overhead lines are designed for multi-decade service lives, the following features were integrated into the design:

a. A maintenance system enabling replacement of cross-arm components without removing the conductors.

b. A conductor stringing capability at all towers equipped with insulating cross-arms.

c.

Although these features were not included in earlier designs, operational feedback has shown them to be necessary. These insights, together with the following requirements:

d.

e.

f.

g.

h.

i. 500-year wind return period (reliability class 3 according to EN 50341:2012)

Increased span length up to 440 m

Development of angle towers for 15 gon (13.5°) and 30 gon (27°)

Improved line redundancy through coordinated failure behaviour

Design simplification

Compatibility with installation on existing towers on the grid, facilitating retrofit potential with minimal required adaptations. j. These drivers led to a next-generation design that fulfils the above requirements while maintaining tower loads within acceptable limits.