1150 kV Transmission Corridor: NCT Clears Rs 68,816 Crore West-East Grid Link

India’s transmission planners have cleared the country’s first 1150 kV transmission corridor, a scheme of about Rs 68,800 crore that will carry Rajasthan’s renewable power east to Chhattisgarh, Odisha and West Bengal. For equipment owners the voltage record is the least useful part. What matters is that the job splits into two very different kinds of site work, and neither starts until an award process that has not yet begun.

What the committee cleared

Reuters reported the clearance on 11 November, and BusinessLine’s M Ramesh read the minutes the next day. Both put the scheme near Rs 68,800 crore and describe it as the highest transmission voltage India has attempted. The corridor was first worked up at a joint planning meeting of the Central Transmission Utility on 21 September. Those minutes size each 1150/400 kV transformer bank at 3,000 MVA, made up of three single-phase 1,000 MVA units.

The decision was not free of doubt. BusinessLine reports that expert member S R Narasimhan, a former head of Grid Controller of India, questioned the 7.64 per cent yearly peak-demand growth the studies assume and warned that the lines could run lightly loaded outside solar hours.

Which machines this work needs

Treat the corridor as two jobs. Each substation, at Raigarh Kotra, Rourkela and Kolaghat, is one large graded platform: dozers, 20-tonne-class excavators, tippers and soil compactors for months, then piling and a batching plant for transformer and reactor foundations. Single-phase transformer units of that rating are heavy, over-dimension lifts, so expect large crawler cranes on site for weeks at a stretch, almost always on hire.

The line is the opposite. It is hundreds of separate tower pits along the route, each a few days of digging, concreting and backfill before the crew moves on. That pattern suits backhoe loaders, small excavators and plate compactors that shift cheaply between locations, and it favours hire over purchase. Ground conditions change along the way too: harder plateau country is typical around Raigarh and Rourkela, while the delta soil near Kolaghat makes piled tower foundations more likely.

No line length appeared in the reports we read, so we have not worked out a per-km rate. Nor is it public whether the substations will be air-insulated or gas-insulated, which decides how much land, and therefore how much earthwork, each yard needs.

Our reading: this is a forward demand signal, not a reason to add machines this season. The dissent recorded in the minutes means the scope could still be phased or trimmed before anyone is awarded the work.

FAQ

Is the 1150 kV corridor approved for construction?

The National Committee on Transmission has cleared it. Allocation and award to an implementing company still have to happen before site work starts, and none has been announced.

How long will it take to build?

Reuters reports about six years. With the award still ahead, heavy civil work this season looks unlikely.

Which machines will the corridor need most?

Earthmoving and compaction plant for the substation platforms, heavy cranes for transformer and reactor lifts, and mobile backhoe and small excavator crews for tower foundations along the line.

Related on DesiMachines: Odisha’s Rs 15,948 crore 765 kV grid approval

Source: BusinessLine