ABSTRACT
High-voltage insulators are designed for the insulation of HV overhead lines and for their mechanical fastening in substations and masts. HV arresters are used for pre-voltage protection of electrical equipment, caused, for example, by a lightning strike in an outdoor HV line. Power switches are used to switch on and off parts of MV circuits in MV substations and overhead lines. Surge arresters are devices used to protect high-voltage electrical. They are always connected in parallel to the protected device. The main parts of the circuit breakers are switching contacts, extinguishing chambers, and a trigger, which automatically disconnects this circuit in the event of a short circuit. For large MV circuit breakers, sulfur fluoride (SF6) or compressed nitrogen is used to suppress arcing between the contacts. Circuit breakers must meet strict requirements for reliability, resistance to dirt, and constant load.
