Title - : Mumbai central lines to switch to AC supply in 18 months

MUMBAI, FEB. 12:   Mumbai commuters on the Central and Harbour suburban railway lines will save between 10 to 20 minutes in 18 months. This will happen when switch-over of the suburban tracks from 1,500 volts DC (direct current) to 25,000 volts AC (alternating current) is completed.

Central Railway General Manager Subodh Jain told Business Line that more than the conversion, the availability of rakes was the critical element in the changeover.

AC conversion brings in higher energy efficiency. It also improves speed in operation and hence faster turnaround time of rakes.

Jain said infrastructure work relating to modification of the signal system to suit the switchover to AC had been completed.

Two substations, one each at Sion and Currey Road, need to be commissioned and Mumbai Rail Vikas Corporation was expected to get it done in a year.

ROLLING STOCK

Rolling stock was the constraint, though the Central Railway was modifying its existing fleet.

The issue of life span of the rakes was an impediment as the Railway’s finance department would want certification of a minimum residual life of 10 years retrofitted. As such, the coaches were already 25 years old or in the end-life cycle,as per rail terminology. In general, the cost of retrofitting an old rake works out to over Rs 3 crore.

“Our DC rakes are on extended life. Railways classify the life span of rakes into mid-life rehabilitation (15 years) and end-life rehabilitation (25 years). These rakes are 25 years old. All DC EMUs will be scrapped and sold.”

Of the total fleet, AC/DC rakes are 50 per cent. The day the conversion happens these rakes would be converted to pure AC rakes with removal of DC motors.

Earlier, the energy cost of suburban operations was 10 to 11 per cent. Now, with energy cost rising, the cost has shot up to 19 per cent. Maintenance and allied activities of the rolling stock work to about 10 per cent.

Jain said the new stainless steel coaches had a distinct advantage. They were regenerating, as they generate power while braking and feed it back. The energy savings in terms of feedback was close 30 per cent.

So, even if old rakes are retrofitted, energy-wise they would remain inefficient, he said.

A concept paper has been sought on the cost of retrofitting and, if scrapped, the extent of monetisation of the AC/DC coaches and locos. Moreover, there should be some standardization in terms of fleet as it becomes a hassle for loco pilots to operate different variety of locomotives, apart from the issues of maintenance, he said.