What does the rated breaking current of the circuit breaker determine about the circuit breaker?

Out-of-step interrupting current is actually mainly for the load switch, the so-called out-of-step breaking is that the two ends of the switch become two independent systems when the switch is disconnected, often one end is connected to a small generator or a small system, the phase on both sides is free drift after disconnection, the recovery voltage between the switch ports may reach up to 2 times the overvoltage, if the insulation recovery speed between the poles after the switch is disconnected can not keep up with the rising speed of the recovery voltage, the switch poles may cause re-breakdown, which may be fatal to the switch. The standard of the out-of-step breaking test is formulated according to such working conditions. Because the out-of-step breaking is not only large in current, but also high in overvoltage, the out-of-step breaking test has become one of the most severe test items in the load switch type test, and its out-of-step breaking ability is also an important indicator of the load switch performance.

The out-of-step breaking current of the general load switch only reaches slightly greater than its rated current, such as the load switch with a rated current of 1250A, the out-of-step breaking current may reach 2000A. Because the short-circuit breaking current of the circuit breaker is generally more than 10 times of its rated current, and the other items carried out by the form test are already harsher than the out-of-step breaking, it is generally not required to carry out the out-of-step breaking test separately, and this index is generally not clearly necessary.

The rated breaking current determines the carrying power of the circuit breaker. The law of power, in the case of a certain voltage, the magnitude of power is proportional to the square of the current. Formula. pi**2xr

The rated breaking current of the circuit breaker determines the carrying power of the circuit breaker. The rated short-circuit breaking current characterizes the circuit breaker's breaking capacity. At the rated voltage, the maximum current that the circuit breaker can ensure reliable breaking is called the rated breaking current, and its unit is expressed in kiloamperes of the RMS value of the periodic component of the short-circuit current at the moment of the circuit breaker contact separation.

When a circuit breaker is operating in a grid below its rated voltage, its interrupting current can be increased. However, due to the limitation of the mechanical strength of the interrupter, the breaking current has a maximum value, which is called the limit breaking current.

The role of the circuit breaker:

The circuit breaker can be used to distribute electric energy, start the asynchronous motor infrequently, protect the power supply line and the motor, and automatically cut off the circuit when they have serious overload or short circuit and undervoltage and other faults, and its function is equivalent to the combination of fuse switch and over/underheat relay. In addition, it is generally not necessary to change the parts after the fault current is switched off. It has been widely used.

In the generation, transmission and use of electricity, power distribution is an extremely important link. The power distribution system includes transformers and various high and low voltage electrical equipment, and the low voltage circuit breaker is a kind of electrical appliances that are widely used.

The circuit breaker is generally composed of a contact system, an arc extinguishing system, an operating mechanism, a tripper, a shell, etc.

When there is a short circuit, the magnetic field generated by the high current (generally 10 to 12 times) overcomes the reaction spring, the tripper pulls the operating mechanism to act, and the switch trips instantaneously. When overloaded, the current becomes larger, the heat generation intensifies, and the bimetal sheet deforms to a certain extent to push the mechanism to act (the larger the current, the shorter the action time).

If there is an electronic type, the transformer is used to collect the current of each phase, and compared with the set value, when the current is abnormal, the microprocessor sends a signal to make the electronic tripper drive the operating mechanism to act.

The rated breaking current of the high-voltage circuit breaker refers to the maximum instantaneous current value that the circuit breaker can cut off the three-phase short circuit.

The rated breaking current of the high-voltage circuit breaker refers to the maximum circuit current that the circuit breaker can break under the rated voltage, and the maximum instantaneous current value generated during the three-phase short circuit is the maximum circuit current that the system may generate.

Refers to the maximum short-circuit current that the circuit breaker can normally cut off under the rated voltage, reflecting the ability of the circuit breaker to cut off the short-circuit current, and the breaking current may be increased in the line below the rated voltage, but due to the limitation of the mechanical strength of the arc extinguishing device, the breaking current cannot be increased at will, and the manufacturer's description is the standard.

It refers to the highest bearing capacity of the circuit breaker, for example, if the rated current of the circuit breaker is 60A, and your electrical appliance exceeds 61A, the circuit breaker will automatically disconnect to protect the circuit.

The rated breaking current refers to the maximum short-circuit current that the circuit breaker can break safely and without damage under the rating.

It should refer to the effective value of the maximum short-circuit current that can be interrupted under the specified conditions.

It refers to the shortening capacity of the circuit breaker in the event of a short circuit.

Because the on-off capacity refers to the limit breaking power of the circuit breaker, when the line is short-circuited less than the current, the circuit breaker can jump away, so that the circuit breaker will not be seriously heated and burned due to thermal stability and dynamic stability, or damaged by electromagnetic force, which does not refer to the trip current (protection current) of the circuit breaker.

The current parameters of the circuit breaker include several values: rated current – the maximum current allowed to pass through during normal operation; Dynamically stabilized current, thermally stabilized current - the limit current parameter (the current passing at the end), that is, the breaking capacity; The above current parameters are specified in the circuit breaker production specification, which is inspected by the manufacturer when leaving the factory, and is the current parameter of the circuit breaker itself.

Hello, the relationship between the short-circuit breaking current of the circuit breaker and the rated current is that the short-circuit breaking current of the circuit breaker is generally greater than the rated current, which is generally times the rated current, so as to ensure that the circuit breaker can cut off the circuit in time when the circuit breaker is short-circuited and prevent damage caused by excessive current during the short circuit. The short opening circuit breaking current of the circuit breaker can also be adjusted according to the user's requirements to meet different usage needs.

Not true.

The on-off capacity of the open circuit should be greater than or equal to the maximum fault current in the line.

1. Select according to the rated voltage, and the rated voltage should be consistent.

2. The rated current of the circuit breaker should be greater than or equal to the rated current of the circuit used.

3. The rated breaking current of the circuit breaker should be greater than or equal to the short-circuit current of the circuit used.

4. Select according to environmental conditions, such as altitude, temperature, humidity, and choose a circuit breaker that meets the requirements.

5. Choose a circuit breaker with high quality and cost performance according to the brand.

6. For special breaking conditions, calibrate the circuit breaker. However, different types of circuit breakers should be used for different loads.