In the university dormitory, the electrical system of the dormitory is set up with a maximum current limit of 20 A, but the actual safety current is only 16 A. Once the current exceeds the safety value, the system will be automatically triggered to trip, and then it is necessary to go to the dormitory management office to manually restore power. The process involves a device called a leakage pulse switch, which disconnects the circuit when it detects an abnormal current, waits about 3 to 20 seconds, and then tries to reapply power through the residual power.
The principle of automatically restoring power after a trip is based on the principle of electromagnets. Excessive current will cause the electromagnet to generate a strong magnetic field that attracts the magnetic part of the trip switch, thus closing the circuit. In addition to high-power electrical appliances, a short circuit or an aging electric gate may also trigger a trip. The power system's protection mechanism is designed in such a way that it can quickly disconnect in the event of a fault, avoiding the expansion of the accident and protecting the safe operation of other equipment and lines.
In a broader power system, such as a traction power system, if a fault occurs, the relay protection device will quickly disconnect the power supply, which is commonly referred to as "tripping", and is designed to protect the stability of the power system and the safety of the overall equipment.