Abstract :
There are two elements involved in providing isolation of the sensitive load from disturbances to (and/or interruption of) the public utility power supply. A series connected device is required to provide buffering from the disturbance and an energy source to provide any shortfall of power input. For most of the time, the series device will be required to present a negligible impedance to normal power from the system and the energy source will need to provide zero power, or perhaps only a small proportion of the total power required by the load. When the disturbance occurs the series device must transform itself into its buffering state with a minimum of delay and the energy source must start to provide all the power needed, as soon as the supply system is adequately buffered. There have been several installations which have achieved these objectives using conventional power circuit components. Buffering between the load and the supply system may be achieved very effectively using a suitable current-limiting reactor but, if it is used by itself, it will prevent satisfactory power transfer under normal conditions. In order to provide buffering when supply system disturbances occur this "resonant link" must be rapidly de-tuned. Two major methods are available for high speed detuning without using a mechanical switch: a spark gap and a saturable reactor
