What is leakage protection and what is overload protection? What is the difference between the two?

There are three aspects to answer this question.

1, leakage protection; in the three-phase four-wire low-voltage power supply line, electrical equipment due to failure of insulation, between the line and the line, between the line and the ground, the working circuit and the non-charged metal shell, frame and other current The path is called leakage.

In order to prevent electric leakage, the device that is subject to electric shock is called electric leakage protection (or leakage circuit breaker). Its working principle is: Under the specified conditions, when the residual current in the circuit to be protected exceeds the set value, it can quickly and automatically disconnect the circuit or relay protection device that sends an alarm signal. The "device" range refers to a series of devices that have a residual current protection function.

The residual current operation protection device adopts the protection principle of the automatic cut-off power supply, and is an additional protection of the basic protection measures against electric shock in direct contact protection. In indirect contact protection as a protection against electric shock due to ground faults that expose the electrical equipment to dangerous parts with a hazardous voltage, or to the risk of electrical shock or electrical fire. The operation principle of the residual current operation protection device to cut off the power supply is different from the overcurrent protection in the line (or in the electric), but depends on the vector sum of the phase lines and the center line (N) when a ground fault occurs in the line. This vector is small enough to have a mA level, but reaches a predetermined value and is amplified by the residual current operation protection device to form a highly sensitive cut-off action to trip the earth leakage breaker and achieve safety.

2, overload protection; the use of two different metal sheet welding, the current in the working current into the thermal element generates heat, so that the bimetal with different expansion coefficients of stress deformation, when the deformation reaches a certain distance (this bimetal has Adjust the distance of the screw, adjust the screw level to change the size or time of its action, and push the linkage mechanism to move, so that the contact circuit breaker control circuit breaker, so that the circuit breaker trip power loss, the main circuit disconnected, to achieve Circuit breaker overload protection.

Domestic manufacturers have all kinds of circuit breakers or ordinary circuit breakers with residual currents that are produced according to the national standard. All of them have overload protection devices. Before shipment, they must have strict detection methods to ensure that they are consistent with the type designation of circuit breakers.

3, overload protection overload current is greater than the rated operating current. For example, a circuit breaker marked with a rated current of 16 A means that the circuit breaker can work in the range of up to 16 A for a long period of time or the maximum operating current of the circuit breaker. While the overload current is greater than 16A, it has one parameter that is the action delay time for the overload. For the residual current circuit breaker, this parameter should be less than 0.3 seconds, and the breaking time is more than 0.5 seconds as an ordinary circuit breaker.

Leakage protection and overload protection are the responsibility of the circuit breakers in the total or in the circuit breakers. One of them is faulty. The function of the circuit breaker is regarded as damaged and should be replaced.