Diesel Generators

Generators come in various sizes, from the small Honda sets giving a few kilowatts to the large 1000 kVA generators. All modern generators are driven by diesel and are provided with large fuel tanks so that the generator can run for many hours without being replenished. One of the problems with diesels is that if it runs out of fuel, it would be necessary to bleed the fuel lines to allow the diesel to run again. On occasions, when it is necessary to run generators for long periods of time without switching off, it may be necessary to make special arrangements to introduce fuel from an external fuel tank system. The generators are normally three-phase and require that the phases are fairly well balanced to ensure that the diesel runs smoothly; the diesels used for the entertainment industry require to be silent running. It is essential that the frequency of supply is kept stable, and this is usually done by fitting electronic governor systems. Normally, the rear of the generator contains a distribution panel which is fitted with voltmeters, ammeters and the various switches required to run the diesel itself. The normal procedure is to wire to the generator from the local distribution units, check all the electrical system is OK and safe and then run the generator, when the generator is running the main switches are applied and electricity is supplied to the system.

In the past and indeed up to quite recently, film studios often generated their own power. This was in the form of a d.c. voltage, usually at 120 V and mainly used because of the need to supply carbon arc sources used in the film industry. The basis of the 120 V was the importation from America of the lighting technology used in film studios. As the public supply authorities did not in general, supply d.c. voltage, it was necessary for the film studio to install large diesel driven generators. Associated with the 120 V systems used was the need to have much larger copper feeder cables than would be normal in the UK, due to the current being used. With the advent of much more sophisticated d.c. power supplies, particularly of a size such as the film industry would demand, it was easier to supply systems with a.c. voltage and transform and rectify it to the 120V needed.