Siemens and  Drax Group have upgraded 30-year old switchgear at the  Cruachan pumped storage plant, including the UK’s first installation of circuit breakers that do not depend on sulphur hexafluoride (SF6) gas.

SF6 gas has  been used in circuit breakers due to its good insulation capabilities, but is a greenhouse gas (see more details here). Siemens’ breakers use vacuum technology instead, so there is no risk of gas leakages and no need for specialist maintenance. They should allow for to ten years of maintenance-free operation at Cruachan.

“With Cruachan playing a vital role in supporting the growth of wind power in Scotland and enabling further decarbonisation of the grid, it is only right that the infrastructure inside the power station is also environmentally friendly,” said Ian Kinnaird, Drax’s Head of Hydro.

Ross Fraser, technical manager, Power & Utilities, Siemens said: “We are delighted that Drax chose this solution for the UK’s first implementation inside a hydro power station. The project was certainly unique as we were working 1km underground at the heart of Ben Cruachan mountain, but by working very closely with the Drax team, we achieved a quick turnaround and had the first unit fitted in under 12 months during planned maintenance downtime.”

The generator circuit breakers were installed after being transported through a narrow, one-kilometre long tunnel that leads deep into Ben Cruachan mountain. The work had to take place over the course of two years during planned maintenance downtime.

Further reading

The worst greenhouse gas: why the electricity industry has to grapple with SF6