The leakage circuit breaker switch is called residual current protection device (hereinafter referred to as RCD), which is a kind of air with special protection function (leakage protection). The residual current is measured, that is, the algebraic sum of the instantaneous values of the current of the phase and neutral lines in the protected loop. To this end, the setting value of RCD, that is, its initial action current IΔn, only needs to avoid the normal leakage current value, which is measured in mA, so RCD can be very active to block the grounding shortcomings of the protection circuit, and can also be used for backup protection against direct touch shock.
The leakage protector is a protective electrical appliance that uses the detection of the phase line to earth leakage or shock current in the protected power grid to announce the action trip signal and end the action trip task. In a low-voltage power network equipped with a leakage protector, under normal circumstances, the grid phase line to ground leakage current is small, can not reach the action current value of the leakage protector, so the leakage protector does not act. When the shortcomings such as leakage or personal shock occur in the protected power grid, when the current of the detection element of the leakage protector reaches its leakage or shock action current value, the leakage protector will have an action trip command, so that the main circuit switch under its control will trip, block the power supply, and then end the task of leakage or shock protection. In addition to the function of the air base, it can also be sensitive to break the switch when there is leakage in the load loop to avoid damage to personnel and the impact on electrical equipment when there is leakage in the load loop.
The air switch is called an air circuit breaker, which is generally low-voltage, that is, the rated operating voltage is 1Kv. Switchgear with multiple protection functions that can block and close circuits at rated voltage and rated operating current. The type of protection function and the protection method are selected by the user according to their needs. Such as short circuit protection, overcurrent protection, shunt control, undervoltage protection and so on. Among them, the first two kinds of protection are air base equipment, and the last two are optional functions. So the air switch can also block the electrical circuit.
The leakage circuit breaker switch cannot replace the air switch. Although the leakage switch has more protection function than the air switch, the possibility of leakage often exists in the working process and the appearance of tripping, resulting in frequent power outages of the load, affecting the continuous and normal work of the electrical equipment. Therefore, it is generally only used in the construction site for temporary electricity or in the socket circuit of industrial and civil buildings. Leakage switch can also be said to be a kind of air switch, mechanical action, arc extinguishing method are similar. However, because the leakage switch protection is mainly personal, the general action value is milliampere level. In addition, the action detection method is different: the leakage switch uses the residual current protection device, and what it detects is the residual current, that is, the algebraic sum of the instantaneous value of the phase line and neutral line current in the protected loop. For this reason, the amount of action current only needs to avoid the normal leakage current value, so it can be very active to block the ground fault and prevent direct touch electric shock.
The air switch is a simple overcurrent trip (amperage), only overcurrent protection and manual operation. The leakage circuit breaker increases the leakage protection, the neutral line is not connected can not play the role of leakage protection, because it monitors the current of 4 lines, it is necessary to offset the positive and negative current is equal to zero, if there is leakage, it is not zero, it jumps. Three-phase four-wire leakage switch can also be connected to three phase lines when the air switch is used, the load short circuit or overcurrent will trip. The zero line of the three-phase four-wire leakage switch must be connected to the purpose of leakage trip, because the decoupling coil power supply of leakage trip is taken from the three-phase line, which is one phase and the zero line.
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