Circuit breaker components

Internal accessories
Auxiliary contact: A contact that is mechanically linked to the opening and closing mechanism of the main circuit of the circuit breaker. It is mainly used to display the opening and closing status of the circuit breaker. It is connected to the control circuit of the circuit breaker to control or interlock its related electrical appliances through the opening and closing of the circuit breaker. For example, output signals to signal lights, relays, etc. The frame rating of the molded case circuit breaker is 100A with a single breakpoint conversion contact, and 225A and above with a bridge contact structure, with a conventional heating current of 3A; the frame rating of 400A and above can be equipped with two normally open and two normally closed contacts, with a conventional heating current of 6A. The number of operating performances is the same as the total number of operating performances of the circuit breaker.
Alarm contact: Alarm contact used for circuit breaker accidents, and this contact will only work when the circuit breaker is tripped and disconnected. It is mainly used for free tripping when the load of the circuit breaker is overloaded, short-circuited or undervoltage. The alarm contact is converted from the original normally open position to the closed position, and the indicator light or bell, buzzer, etc. in the auxiliary circuit are connected to display or remind the fault tripping state of the circuit breaker. Since the probability of free tripping of the circuit breaker due to load failure is not too high, the life of the alarm contact is 1/10 of the life of the circuit breaker. The working current of the alarm contact generally does not exceed 1A.
Shunt release: The shunt release is a release excited by a voltage source, and its voltage is independent of the main circuit voltage. The shunt release is an accessory for remote control of the tripping. When the power supply voltage is equal to any voltage between 70%-110% of the rated control power supply voltage, the circuit breaker can be disconnected reliably. The shunt release is a short-time working system, and the coil energization time generally cannot exceed 1S, otherwise the line will be burned. To prevent the coil from burning, a micro switch is connected in series with the shunt release coil of the molded case circuit breaker. When the shunt release is attracted by the armature, the micro switch changes from the normally closed state to the normally open state. Since the control line of the shunt release power supply is cut off, even if the button is pressed manually, the shunt coil will never be energized, which avoids the occurrence of coil burning. When the circuit breaker is closed again, the micro switch is in the normally closed position again.
Undervoltage release: The undervoltage release is a release that causes the circuit breaker to disconnect with or without delay when its terminal voltage drops to a certain specified range. When the power supply voltage drops (even slowly) to 70% to 35% of the rated working voltage, the undervoltage release should operate. When the power supply voltage is equal to 35% of the rated working voltage of the release, the undervoltage release should prevent the circuit breaker from closing; when the power supply voltage is equal to or greater than 85% of the rated working voltage of the undervoltage release, the circuit breaker should be reliably closed under hot conditions. Therefore, when a certain voltage drop occurs in the power supply voltage of the protected circuit, the circuit breaker can be automatically disconnected to cut off the power supply, so that the load electrical appliances or electrical equipment below the circuit breaker are protected from damage by undervoltage. When in use, the undervoltage release coil is connected to the power supply side of the circuit breaker, and the circuit breaker can only be closed after the undervoltage release is energized.