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Air circuit breaker

Air switch, also known as air circuit breaker, is a type of circuit breaker. It is a switch that automatically opens whenever the current in the circuit exceeds the rated current.

Description

Poles Number:3, 1,2,3,4
Rated voltage:110/220 (1P), 240/415 (2P), 41
Mechanical Life:more than 16000 operations
Electrical Life(Time):more than 6000 operations
Color:black
quality:good
Advantage:small size, light weight, novel stru

Definition

Air switch, also known as air circuit breaker, is a type of circuit breaker. It is a switch that automatically opens whenever the current in the circuit exceeds the rated current. Air switch is a very important electrical appliance in low-voltage power distribution network and electric drive system. It integrates control and multiple protection functions. In addition to completing contact and breaking the circuit, it can also protect short circuits, severe overloads and undervoltages that occur in circuits or electrical equipment, and can also be used to start the motor infrequently.

Features

1.The guide rail type installation

2.Durable

3.High breaking capacity

4.Easy to operate

5.Stable performance

6.Rapid arcing

7.Modular form Shell

8. Fire retardant coating

9. High electrical performance

Function and role

Under normal circumstances, the armature of the overcurrent release is released; once a severe overload or short circuit fault occurs, the coil connected in series with the main circuit will generate a strong electromagnetic attraction to attract the armature downward and lift the lock hook. Open the main contact. The work of the undervoltage release is just the opposite. When the voltage is normal, the magnetic attraction attracts the armature and the main contact is closed. In the event of a severe voltage drop or power failure, the armature is released and the main contact is opened. When the power supply voltage returns to normal, it must work again after closing, which realizes voltage loss protection.

Principle

There are three tripping modes: thermal, electromagnetic and multiple.

When the line is generally overloaded, although the overload current cannot make the electromagnetic trip, but it can generate a certain amount of heat in the thermal element, promote the bimetal sheet to heat up and bend, push the lever to disengage the hook from the lock, and the main contact The head is disconnected and the power is cut off. When a short circuit or severe overload current occurs on the line, the short-circuit current exceeds the instantaneous trip setting current value. The electromagnetic release generates a large enough suction force to attract the armature and strike the lever, so that the hook rotates upward around the shaft seat to disengage the lock. Under the action of the reaction spring, the lock buckle disconnects the three main contacts and cuts off the power.

The tripping mechanism of the switch is a set of connecting rod device. When the main contact is closed by the operating mechanism, it is locked in the closed position by the lock hook. If a fault occurs in the circuit, the relevant tripper will act to disengage the lock hook in the trip mechanism, so the main contact is quickly opened under the action of the release spring. According to different protection functions, trip units can be divided into over-current trip units and voltage-loss trip units.

Classification

Low-voltage circuit breakers are classified according to different quenching media. Circuit breakers using air as the arc extinguishing medium are called air circuit breakers (air switches); circuit breakers using inert gas as the arc extinguishing medium are called inert gas circuit breakers. (Inert gas switch); circuit breakers that use oil as the arc extinguishing medium are called oil circuit breakers (oil switches).

Structure

Internal accessories
Auxiliary contact: The auxiliary contact is the mechanical linkage contact 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 through the opening and closing of the circuit breaker. , Control or interlock its related appliances. For example, output signals to signal lights, relays, and so on. The rated current of 100A for the molded case circuit breaker is a single-breakpoint conversion contact, the bridge contact structure of 225A and above, the agreed heating current is 3A; the rated current of the rated 400A and above can be installed in two normally open Close, the agreed thermal current is 6A. The number of operating performances is the same as the total number of operating performances of the circuit breaker.

Alarm contact: It is used for the alarm contact of the circuit breaker accident, and this contact will act only when the circuit breaker trips and breaks. It is mainly used for tripping and alarming when the load of the circuit breaker has an overload short circuit or under voltage. The contact is changed from the original normally open position to the closed position, and the indicator light, electric bell, buzzer, etc. in the auxiliary circuit is turned on to display or remind the fault trip status of the circuit breaker.

Because the probability of a circuit breaker tripping freely due to a 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: It is a release that is excited by a voltage source. Its voltage can be independent of the main circuit voltage. Shunt release is an accessory for long-distance operation. 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 reliably opened. Shunt release is a short-time work system, the coil energization time generally can not exceed 1S, otherwise the wire will be burned. In order to prevent the coil from burning out, a micro-switch is connected in series with the shunt trip coil. When the shunt trip is engaged by the armature, the micro switch switches from normally closed to normally open. The control circuit is cut off. Even if the button is artificially held down, the shunt coil is no longer energized to avoid coil burnout. When the circuit breaker is closed again, the micro switch is in the normally closed position again.

Undervoltage release: An undervoltage release is a type of release that causes the circuit breaker to open with or without delay when its terminal voltage drops to a specified range. When the power supply voltage drops (or even (Slowly falling) to the range of 70% to 35% of the rated operating voltage, the undervoltage release should operate. When the power supply voltage equals 35% of the rated operating voltage of the release, the undervoltage release It can prevent the circuit breaker from closing; when the power supply voltage is equal to or greater than 85% of the rated operating voltage of the undervoltage release, the circuit breaker should be reliably closed under the thermal condition. Therefore, when a certain voltage drop occurs in the power supply voltage in 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 undervoltage damage. When in use, the undervoltage release coil is connected to the power supply side of the circuit breaker. The circuit breaker can be closed only after the undervoltage release is energized, otherwise the circuit breaker cannot be closed.

External accessories
Electric operating mechanism: It is an accessory for long-distance automatic opening and closing circuit breakers. There are two types of electric operating mechanism: electric motor operating mechanism and electromagnet operating mechanism. 400A and above circuit breakers, electromagnet operation mechanism is suitable for circuit breakers with a rated current of 225A and below for plastic shell interrupter housings. Whether it is an electromagnet or a motor, their pull-in and rotation directions are the same. The position of the cam inside the mechanism is used to achieve closing and opening. When the circuit breaker is operated by the electric mechanism, the circuit breaker should be reliably closed at any voltage between 85% and 110% of the rated control voltage.

Rotating operation handle: It is suitable for plastic case circuit breakers. A mechanism for rotating the operation handle is installed on the cover of the circuit breaker. The rotating shaft of the handle is installed in the matching hole of the mechanism. The handle is installed on the shaft head exposed on the door of the complete set of devices, and the round or square seat of the handle is fixed on the door with screws. This installation enables the operator to turn clockwise or counterclockwise through the handle of the handle outside the door. Make sure the circuit breaker is closed or opened. At the same time, turning the handle can ensure that the cabinet door cannot be opened when the circuit breaker is closed; only when the handle is turned on or off, the door of the switch board can be opened. In an emergency, when the circuit breaker is in the “closed” state and the door panel needs to be opened, the red release button on the side of the turning handle seat can be pressed.

Extension handle: It is an external extension handle that is directly installed on the handle of the circuit breaker. It is generally used for large capacity circuit breakers of 600A and above for manual opening and closing operations.

Handle locking device: a clip is installed on the handle frame, a hole is punched in the handle and then locked with a padlock. It is mainly used when the circuit breaker is in the closed working state, which does not allow other people to open and cause a power outage, or when the circuit on the load side of the circuit breaker needs to be repaired or is not allowed to be energized to prevent people from closing the circuit breaker by mistake, thereby protecting Safety of maintenance personnel or reliable use of electrical equipment.

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