Alternate current not cheaper to run Metro, says MMRDA official

MUMBAI: A senior MMRDA official has challenged the popular notion that Metro operation on alternate current (AC) mode is cheaper than on direct current (DC) by proving

MUMBAI: A senior MMRDA official has challenged the popular notion that Metro operation on alternate current (AC) mode is cheaper than on direct current (DC) by proving that the former’s 15% power consumption is not accounted for.

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SP Khade, director (technical) at Mumbai Metropolitan Region Development Authority (MMRDA), carried out experiments with power consumption in AC mode for two years, in which he found that about 15% of power usage was not counted by the meter due to error in the measuring methodology.

He said the problem occurred due to flaws in the prevalent method for measurement of electricity, which also revealed that AC operations are costlier compared to DC. Khade has applied for patent at national and international levels for his findings.

“During the experiments, I observed that meter would show 100 units, though 115 units were consumed. There were issues with metering process. The outcome suggests that the power consumption in AC mode is not cheaper but costlier than that in DC mode,” Khade said.

The findings are significant as almost all Metro implementation agencies in the country have adopted 25KV AC instead of 1,500 V DC, following Delhi Metro example.

Khade claimed his findings were going to dispel the myth that AC mode is cheaper and more efficient than the DC one, which will impact not just Metro agencies but electricity distribution companies as well. He said not just power consumption but building infrastructure for DC mode is also cheaper.

Although about 97% of Metros in the world run on DC mode, policymakers have given preference to AC mode for Metros in the country including Delhi and Mumbai. “Requirement of substations at every 10 km to 15 km is shown as a major reason for rejection to DC. However, substations for DC are relatively very small in size and they can be built on elevated corridor, as we have built one in Lower Parel for Monorail. DC mode has a number of advantages,” Khade said.

Meanwhile, those who support AC system claimed that DC system is outdated technology and it cannot be used on longroutes. Khade refuted the ‘outdated’ claims but accepted that it cannot be used for long-distance trains including suburban ones.