Switching from AC to DC causes blaze in local train
Technical error during switchover from 25,000-V AC to 1,500-V DC at Mahim causes oil to leak from transformer box and catch fire at Dockyard Road station
Upgradation of power from 1,500-volt Direct Current (DC) to 25,000-volt Alternating Current (AC) to increase the speed of trains, conserve electricity and reduce travel time showed a darker side yesterday.
A malfunction in the pantograph above the motor coach is believed to have occurred during a switchover from AC to DC after the train passed Mahim. The line runs on 25,000-volt AC till Mahim, after which it switches over to 1,500-volt DC towards CST.
By the time the train reached Dockyard Road, leaking oil from a hot transformer erupted into flames when the brakes were applied.
Although railway officials are terming the incident as unusual since it occurred on the suburban section, which is fed by 1,500 volt DC, chances of a repeat in future cannot be ruled out.
Railway officials believe that the only possible cause behind yesterday’s incident lies in the incomplete work of power conversion from DC to AC, which is 17-times stronger.
Presently, the electricity supply to trains has been augmented on the Western Railway (WR) section to 25,000-volt, which powers trains on the main line and harbour line starting from Andheri. Central Railway (CR) on the other hand has undertaken power conversion to 25,000-volt AC in six phases on sections of CST-Thane, CST-Panvel, Thane-Vashi and Wadala-Kings Circle.
“Normally when a train crosses a point that receives both DC and AC supply, the motorman pushes a button allowing the pantograph to adjust accordingly. However, in this case it seems that one of the components of the pantograph above the affected coach got stuck, resulting in the incident,” said a CR official on condition of anonymity.
Under normal circumstances, the motorman can control the quantum of power supply received by the train through the pantograph. Once this happens, the altered power supply from the overhead cables is transferred to the transformer inside the coach via the pantograph and to the drive motors.
“It is quite likely that the pantograph didn’t respond to the change applied by the motorman due to malfunction as it crossed Mahim. By the time it reached Dockyard Road, a lot of heat would have been generated in the transformer and when the brakes were applied, it could have caused a fire coupled with oil spilling out of the box below the coach,” said another CR official.
Dockyard Rd scare
The Andheri-CST local was running late by a minute and arrived at Dockyard Road station at 11.19 am. Commuters heard an explosion and felt splatters of a liquid hitting them, and suddenly flames spewed from beneath the coach.
“Prima-facie, the incident involves malfunctioning of a transformer located in the second coach of the train, which resulted in leakage of transformer oil. This is what we suspect caused burn injuries to some passengers,” said V Malegaonkar, chief PRO, CR.
The guard, who is generally stationed at the rear of the train reached the stricken coach with a fire extinguisher and tried dousing the flames. At around 11.35am, fire tenders reached the spot and by 12.10 pm, the train finally left Dockyard Road station while commuters were being taken to JJ and St George hospitals. The train reached CST at around 12.20 pm, by which time all the passengers had detrained at their respective halts.