The electrical circuit includes main circuit auxiliary circuit.
The switches in the auxiliary circuit include air switch, travel switch, button switch, transfer switch, micro switch, auxiliary switch, etc.
The auxiliary switch is generally composed of several pairs of normally open normally closed auxiliary contact units. After a mechanical action is completed, the mechanical action is transmitted to the auxiliary switch through connecting rod plate other parts, so that the normally open normally closed auxiliary contacts in the auxiliary switch can be switched to each other, so as to realize the signal circuit, energy storage circuit closing circuit connected with the auxiliary switch contact On off switching of circuit opening circuit.
Because the contact capacity of auxiliary switch is large, it is mainly designed for application in auxiliary circuit, so it is called secondary circuit auxiliary switch, referred to as auxiliary switch.
The structure of auxiliary switch is diverse, the expansion capacity, capacity, life, reliability, shape installation price of contact pairs are different. Therefore, the auxiliary switch should be selected according to the actual requirements.
Any switch other than the main circuit switch can be called an auxiliary switch. In addition to the high-voltage main circuit, the high-voltage power supply system is the secondary circuit, such as control circuit, metering circuit, detection circuit, etc.
Secondary circuit is defined as all low-voltage circuits such as measurement circuit, relay protection circuit, switch control signal circuit, operating power supply circuit, electrical locking circuit of circuit breaker disconnector. The electrical circuit composed of the secondary equipment connected with each other to monitor, control, regulate protect the primary equipment is called the secondary circuit. It is a circuit which is connected by control cable through secondary winding of transformer, measuring monitoring instrument, relay automatic device in electrical system. It is used to control, protect, adjust, measure monitor the working conditions of various parameters elements in the primary circuit. The circuits used to monitor measure meters, control operation signals, relay protection automatic devices are called secondary circuits secondary wiring.