Circuit breakers are divided into high-voltage circuit breakers and low-voltage circuit breakers according to their use range. The division of high and low voltage lines is relatively vague. Generally, 3kV or more is called high-voltage electrical appliances, and the following are low-voltage electrical appliances.
Auxiliary contact
The contact with the mechanical circuit of the main circuit of the circuit breaker is mainly used for the display of the circuit breaker's split and closed state. The control circuit of the circuit breaker is connected to the control circuit of the circuit breaker to control the related electrical appliances. Or interlocking. For example, a signal is output to a signal lamp, a relay, or the like. Molded case circuit breaker frame rated current 100A for single breakpoint conversion contacts, 225A and above for bridge contact structure, the agreed heating current is 3A; frame rated current 400A and above can be installed with two normally open, two often Closed, the agreed heating current is 6A. The number of operational performances is the same as the total number of operational performance of the circuit breaker.
Alarm contact
The alarm contact for the circuit breaker accident, and the contact only acts when the circuit breaker is tripped and disconnected, and is mainly used for free tripping when the load of the circuit breaker is overloaded or under voltage, and the alarm contact is from the original The normally open position is converted into a closed position, and the indicator light or bell, buzzer, etc. in the auxiliary line is turned on, and the fault trip state of the circuit breaker is displayed or reminded. Since the probability of free tripping of the circuit breaker due to load failure is not too much, the life of the alarm contact is 1/10 of the life of the circuit breaker. The operating current of the alarm contact will generally not exceed 1A.
Shunt release
A shunt trip is a trip that is energized with a voltage source whose voltage is independent of the main circuit voltage. The shunt release is an accessory for remotely operated trips. When the power supply voltage is equal to any voltage between 70% and 110% of the rated control power supply voltage, the circuit breaker can be reliably disconnected. The shunt release is a short-time working system, and the coil energization time can't generally exceed 1S, otherwise the line will be burned. In order to prevent the coil from being burnt, the molded case circuit breaker is connected with a micro switch in the shunt trip coil. When the shunt release is engaged by the armature, the micro switch is switched from the normally closed state to the normally open state, due to the shunt release power supply. The control line is cut off, and even if the button is manually pressed, the shunt coil will never be energized again, which avoids the occurrence of coil burnout. When the circuit breaker is reclosed, the micro switch is in the normally closed position again.
Undervoltage release
An undervoltage release is a type of trip that allows the circuit breaker to be delayed or without delay when its terminal voltage drops to a specified range. When the supply voltage drops (or even slowly drops) to the rated operation. The undervoltage release shall operate within the range of 70% to 35% of the voltage. The undervoltage release shall prevent the circuit breaker from closing when the supply voltage is equal to 35% of the rated operating voltage of the trip unit; When the power supply voltage is equal to or greater than the rated working voltage of the 85% 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 equipment or electrical equipment below the circuit breaker is protected from undervoltage. When in use, the undervoltage release coil is connected to the power supply side of the circuit breaker, and the circuit breaker can be closed after the undervoltage release is energized, otherwise the circuit breaker cannot be closed.
Concerned about surprises
Label: Internal accessories for circuit breakers
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