The protection scheme for a power system should cover the whole system against all probable types of faults. Unrestricted forms of line protection such as over current and distance systems, meet this requirement, although faults in the Bus bar zone are cleared only after some time delay. If unit protection is applied to feeder and plant the bus bars are not inherently protected. Bus bars have been left without specific protection. Different bus bar faults are as follows.

Busbar Faults

·         Majority of bus faults involve one phase and earth, but faults arise from many causes and a significant number are inter-phase clear of earth.

·         With fully phase-segregated metal clad gear, only earth faults are possible ,and a protective scheme need have earth fault sensitivity only.

·         For outdoor busbars , protection schemes ability to respond to inter-phase faults clear of earth is an advantage

Types Of Protection Schemes