Air switch works - Solutions - Huaqiang Electronic Network

Probe domestic switch needle KG-300K, with a needle head diameter of 3.0mm, is a normally open switch needle.

SMD aluminum electrolytic capacitor, ideal for high-performance and compact electronic designs.

MOS power IC series covering a full range of applications for efficient power management.

Industrial Router Crystal, 3.2x2.5mm, 3225 package, 26MHz (26.000MHZ), 12PF, available in 10PPM, 20PPM, 30PPM specifications.

An air switch, also known as a circuit breaker, serves as a critical component in electrical systems. It connects, disconnects, and carries the rated working current in the circuit. In case of overload, short circuits, or under-voltage conditions, it provides reliable protection. The design of its moving and static contacts, along with contact rods, allows for parallel operation. During a short circuit, the dynamic repulsive force helps to quickly separate the contacts, offering high breaking capacity and strong current limiting characteristics.

When a short circuit occurs, the insulating material around the static contact vaporizes, leading to immediate arc extinction. This results in zero arc distance. The arc-extinguishing chamber uses a metal grid structure, and the contact system includes a repulsive current-limiting mechanism. These features ensure that the circuit breaker can handle high breaking capacities and effectively limit current during faults.

The circuit breaker is equipped with a dual release mechanism. One is the thermal release, which operates based on the heat generated by the bimetallic strip, while the other is the electromagnetic release, which acts instantly when a large current flows. There are three types of tripping methods: thermal, electromagnetic, and combined tripping.

During a short circuit or severe overload, the short-circuit current exceeds the set threshold, causing the electromagnetic release to generate enough magnetic force to pull the armature and trigger the trip mechanism. This action disengages the lock, allowing the main contacts to open and cut off the power supply rapidly.

In cases of general overload, the electromagnetic release may not activate, but the heat generated by the overload current causes the bimetallic strip to bend, pushing the lever and disengaging the lock. This action opens the main contacts, cutting off the power supply to protect the system from damage.

The main contacts are closed by an operating mechanism, either manual or electric. Their contact system is designed to handle both normal working currents and fault conditions through an arc suppression device. In the event of a fault, the tripping current can be several times higher than the normal current, ensuring rapid disconnection. Once closed, the main contacts are locked in place by a hook mechanism. If a fault occurs, the relevant trip unit activates, releasing the hook and allowing the spring to quickly open the contacts. Trip units can be classified into overcurrent releases and voltage loss releases, depending on their protective function.

The overcurrent release’s armature remains released under normal conditions. However, during severe overloads or short circuits, the coil in series with the main circuit generates a strong magnetic field, pulling the armature and opening the hook to disconnect the main contacts. The undervoltage release works oppositely. When the voltage is normal, the electromagnetic force keeps the armature engaged, allowing the main contacts to close. If the voltage drops significantly or is lost, the armature is released, opening the contacts. To restore power, the circuit must be manually re-closed, providing effective voltage loss protection.