A simple diagram show the basic component functions within switchgear as following items:
- supply-side and load-side conductors.
- insulation from earth to support the conductors.
- a moving contact arranged to be able to join, or separate, the two conductors.
- a driving mechanism and drive linkage to the moving contact.
The conductors(a) are required to carry electrical current and will, therefore, generate heat due to their internal resistance, and will also be subjected to mechanical forces
due to the electromagnetic effects of electrical current.
The insulators(b) are required to provide electrical insulation to earth to withstand both the system voltage and any transient voltages which may be impressed upon
the switchgear .
The moving contact(c),like the conductors, will also be subjected to heat and mechanical forces. It can be expected that the potential for heat generation will be
greater in the moving contact as it will have a transfer contact at its hinge, and spring loaded contacts at its separable end.
The operating mechanism(d) to drive the moving contact between the open and closed positions and to withstand the electromagnetic forces that may be generated when a short circuit occur