Low-voltage molded case circuit breaker is a very important protection device in modern power distribution system. It integrates manual control function and automatic protection function, which not only ensures the flexibility of operation, but also ensures the safety of electricity. Its working principle is mainly based on real-time monitoring of electrical parameters of the circuit, and quickly cut off the circuit when abnormal conditions such as overload, short circuit, undervoltage, etc. occur.
Contact system: responsible for conducting current under normal conditions and breaking the circuit quickly when tripping.
Arc extinguishing system: used to extinguish the arc generated during analysis and prevent equipment damage.
Operating mechanism: manual or electric closing and opening, generally free tripping mechanism.
Release: used to detect faults and trigger tripping action, common types include thermomagnetic (bimetal for overload protection, electromagnetic coil for short-circuit protection) or electronic (through transformer sampling, microprocessor control).
Enclosure: provides insulation, protection and structural support, usually molded from high dielectric strength materials.
Normal operation: under safe load conditions, the main contact remains closed, the current continues to pass normally, and the free tripping mechanism is in the locked position.
Overload protection: when the circuit overload occurs and lasts for a certain time, the bimetal in the thermal trip device is heated and bent to push the trip mechanism to act, and its action time is inversely proportional to the overload current.
Short-circuit protection: When short-circuit occurs, the current rises sharply (usually 10 - 12 times the rated current), and the electromagnetic coil of the magnetic release generates enough magnetic force to attract the armature instantaneously, and the impact free release mechanism realizes millisecond fast breaking.
Optional undervoltage protection: the coil of undervoltage release is connected in parallel on the power supply side. When the line voltage is lower than the set value, its armature releases and drives the mechanism to trip.
Arc extinguishing process: contact analysis instantly produces arc, arc extinguishing grid will be divided, cooled and elongated, accelerate ion recombination, so that the arc quickly extinguished and restore insulation strength.
Modern circuit breakers have been widely used electronic release, through the current transformer real-time monitoring of each phase current, and set value comparison. Once an abnormality is detected, the microprocessor sends a signal to drive the electronic trip element, which drives the operating mechanism to act. This method has higher precision, richer functions, and can realize communication and remote control.
Set overload, short circuit, undervoltage and other protection in one.
High breaking ability, adjustable action value, good selectivity.
Safe and convenient operation, support frequent manual and remote automatic control.
Compact structure, easy installation and maintenance.
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