Context: Railway Ministry is upgrading all existing Linke Hofmann Busch (LHB) coaches with the Head on Generation (HOG) technology.

Significance: This would cause the trains to become more cost-efficient and less polluting.

What is Head on Generation (HOG) technology?

• The system runs the train’s ‘hotel load’ (the load of air conditioning, lights, fans, and pantry, etc.) by drawing electricity from the overhead electric lines through the pantograph.
• The power supply from the overhead cable is 750 volts at single-phase, and a transformer with a winding of 945 kVA converts it to a 750 Volts 50 Hz output at 3-phase. This energy is then provided to the compartments.

How is it different from the present EOG technology?

Under the End on Generation (EOG) system, the train’s ‘hotel load’ (the load of air conditioning, lights, fans, and pantry, etc.) is provided with electricity from two large diesel generator sets, which supply 3-phase power at 750 Volts 50 Hz to the entire length of the train.

Each coach then picks up the power supply through a 60 KVA transformer, bringing down the voltage to 110 volts at which level the equipment in the compartment is run. The generator cars are attached to either end of the train, giving the system its name.

Benefits of HOG over EOG:

• Since the HOG-fitted trains do not require power from diesel generators at all, they only have one emergency generator car attached, instead of two regular generator cars.
• The extra space created would now be used for an LSLRD (LHB Second Luggage, Guard & Divyaang Compartment)– meaning more passengers can be accommodated.
• Cost savings would be significant: Once all LHB trains get the new system, NR 1390 crores would be saved every year.
• HOG system is free of air and noise pollution: It would bring down yearly CO2 and NOx emissions, which are currently at 1724.6 tonnes/annum and 7.48 tonnes/annum respectively, to zero.
• The reduction in emissions could also help the Railways accrue carbon credits, and trade them on the international market.
• With the noise-emitting generator sets gone, noise pollution would also drop.