Head-end power

In rail transport, head-end power (HEP), also known as electric train supply (ETS), is the electrical power distribution system on a passenger train. The power source, usually a locomotive (or a generator car) at the front or 'head' of a train, provides the electricity used for heating, lighting, electrical and other 'hotel' needs. The maritime equivalent is hotel electric power. A successful attempt by the London, Brighton and South Coast Railway in October 1881 to light the passenger cars on the London to Brighton route heralded the beginning of using electricity to light trains in the world. Oil lamps were introduced in 1842 to light trains. Economics drove the Lancashire and Yorkshire Railway to replace oil with coal gas lighting in 1870, but a gas cylinder explosion on the train led them to abandon the experiment. Oil-gas lighting was introduced in late 1870. Electrical lighting was introduced in October 1881 by using twelve Swan carbon filament incandescent lamps connected to an underslung battery of 32 Faure lead-acid rechargeable cells, suitable for about 6 hours lighting before being removed for recharging. The North British Railway in 1881 successfully generated electricity using a dynamo on the Brotherhood steam locomotive to provide electrical lighting in a train, a concept that was later called head-end power. High steam consumption led to abandonment of the system. Three trains were started in 1883 by London, Brighton and South Coast Railway with electricity generated on board using a dynamo driven from one of the axles. This charged a lead-acid battery in the guard's van, and the guard operated and maintained the equipment. The system successfully provided electric lighting in the train. In 1885, electric lighting was introduced in trains in Frankfurt am Main using a Moehring-type dynamo and accumulators. The dynamo was driven by pulleys and belts from the axle at speeds of 18 to 42 mph, and at lower speeds the power was lost.