Commissioning substations in the mountains

Several of our transmission projects are in Himachal Pradesh, including 400/220 kV gas-insulated substations at Gumma and Wangtoo for HPPCL, and running works at Hilling and Kangu for HPTTCL. Mountain sites bring problems that plains projects rarely face.

A short working season

Snow, landslides and monsoon damage close roads and stop outdoor work for parts of the year. The schedule has to be built around the months when equipment can reach the site and crews can work safely, with indoor and testing work planned for the rest.

Why gas-insulated switchgear

Hill sites rarely have the flat land an air-insulated substation needs. Gas-insulated switchgear takes far less space, which is why it is common in these locations. It also requires clean, controlled conditions during erection, which is harder to maintain on an exposed mountain site.

Getting equipment up the hill

Transformers and switchgear modules are heavy and large. Routes, bridges and turning radii have to be checked well before dispatch, and some deliveries have to wait for road repairs. On these projects, logistics planning is as important as the electrical design.

Testing and handover

Commissioning is the point at which delays become visible to everyone. Careful testing in the right sequence, with the client's engineers involved throughout, avoids surprises at energisation.

The same discipline applies to our plains projects, from 765 kV substations in Rajasthan to metro receiving substations in Delhi. The mountains simply leave less room for error.