E.S.M. conducted a study to develop and apply a risk-management model for the points of isolation used by workers on high-voltage (HV) electricity transmission substations. The study focussed on HV switchgear and analysed the protective layers in their design, including the electrical and mechanical lock-off mechanisms.

This was a large multifaceted project, conducted by a team of four E.S.M. engineers, over a period of three years, involving state-wide travel.

By analysing the initiating events and failure rates of protective layers, including mechanical failures and human error, E.S.M. developed and applied a quantified risk-management model for switchgear.

The analysis included a review of the design of electrical and mechanical lock-off and interlocking mechanisms and made recommendations for improvement of designs and asset management practices.

The analysis identified shortcomings in the identification and effectiveness of existing safeguards in various operating modes.

Several types of switching assets were covered, including; Motorised and Non-motorised Air-Insulated Switchgear (AIS), Gas-Insulated Switchgear (GIS), Hybrid Switchgear, Earth Switches, Metal Enclosed Switchgear (MES) and Ring Main Units (RMUs).

As a result of E.S.M.’s work, the Client invested more than $11M in new, safer switchgear. This further investment and related work, enabled the Client to demonstrate reduced overall business risk, improved safety outcomes for workers, and compliance with WHS legislative requirements.