Diesel Generators Switchgear

When using powers of hundreds of kilowatts, it perceptibly makes sense to have large transformers very close to the areas troubled. This enables high voltage feeds, say 11 kV, to be fed to local sub-stations and then be misshapen down to a 415 V three-phase system. One snag with having the transformer very close to the dimmer room is that the impedance of the cables between the dimmer cabinets and the transformer is tremendously low and allows very high fault currents to occur. This means that the dimming equipment supplied will have to meet demanding tests.

In the smaller setting up, it will perceptibly not be sensible to allow the lighting system to be fed from its own transformer and it will have to share power necessities with the remainder of the building. In larger installations however, it is preferable that the lighting system has its own transformer and when systems are of the order of 500 kW this makes life so much easier. It may also be probable in the very large setting up that two studios can share a transformer and even bigger transformers can be installed. It can be advantageous to have a dimmer room with two sets of switch gear, fed by a common transformer, covering two studios.

In the past, due to the British system pertaining at the time, which treated single and three-phase working voltages differently, it was very difficult to feed the lighting system effectively from three-phase provisions, owing to the need for defined limits of taking apart between socket outlets on different phases. In practice, this often meant that all floor sockets were on the same phase as the technical equipment. In trucking arrangements with socket outlets fitted and particularly on barrels, it was difficult to prevent clusters of equipment appearing on the same phase causing large imbalances over the three phases. The main reason was that studios had to have the personality barrel outlets on the same phase; thus one third of the barred. Sets any voltage up to that of 1000V a.c. between conductors, or 600 V a.c. between conductors and earth, as low voltage.