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

Mumbai commuters on the
Central and Harbour suburban
railway lines will save between
10 to 20 minutes in 18 months.
This will happen when
switchover 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
standardisation 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.