SWITCHGEAR

The great demand for electrical energy is a notable feature of modern civilisation. Most of this energy is need for lighting, heating, domestic appliance, Industrial electrical machinery and electric traction. The importance of electric supply in every day life has reached such a stage that it is desirable to protect the power system from harm during fault condition and to ensure maximum continuity of supply. For this purpose, means must be provided to switch on or off generators, transmission lines distribution and other equipment under both normal and apparatus called switchgear. A switchgear essentially consists of switching and protecting devices such as switches,fuse, circuit breakers, relays. during normal operation, switchgear permits to switch on or off generators, transmission lines, distributors and other electrical equipment. On the other hand,when a failure occurs on any part of power system, threatening damage to the equipment and interruption of service to the customer. However, the switchgear detects the fault and disconnects the unhealthy section from the system. in this way, switchgear protects the system from the damage and ensures continuity of supply.

the switchgear equipment is essentially concerned with switching and interrupting currents either under normal or abnormal operating conditions. The tumbler switch with ordinary fuse is the simplest form of switchgear and is used to control and protect lights and other equipment in homes, offices, circuit of light rating, a high rupturing capacity fuse in conjunction with a cannot be used profitably on high voltage system. when a fuse blows, its takes some times to replace it and consequently there is interruption of service to the customers. the fuse cannot successfully interrupt large fault currents and that result from the faults on high voltage system.