Equipment consisting of main lines, isolation switches (high voltage), knife switches (low pressure), circuit breakers (air switches), voltage sensors, current sensors, electrical transformers, communication contacts, protection relays (thermal relays), and mine avoidance devices are referred to as one-time equipment in the electrical kit. The circuits formed by them in accordance with the rationale are referred to as one circuit or one programme map.

In order for a system to operate safely and securely, it is necessary to monitor the operational status of the system at all times, and to control the system at all times, many other electrical elements and equipment must be equipped. e.g. metering meters (current meters, voltage meters, power factor meters, power meters, frequency meters, etc.), control signal elements (lights, buttons, all-power conversion switches, etc.), relay protective devices, etc. The circuits formed by them according to their rationale are referred to as secondary circuits or secondary scenarios.