Leakage protector role and scope of use - Database & Sql Blog Articles

LC03-3.3 SOP8 TVS Static Protection 3.3V

The leakage protector has a sensitive action and a fast cutting-off performance. As long as it is reasonably selected and properly installed in the electrical design and construction of the building, it will have a significant effect on protecting personal safety and preventing equipment damage, as well as preventing flames.
(1) When the human body is in direct contact with the 220V charged body, the leakage protector quickly cuts off the circuit quickly in 0.1 second. At this time, the electric shock current flowing through the human body (generally the human body resistance is about 1 000 Ω) is 220 / 1 000 = 220 (mA), and the electric shock energy is: 220 (mA) × 0. 1 (S) = 22 mA · S < 30 mA ·S. At present, China's current regulations: the electric shock energy for human body safety is: 1·T = 30mA·S. It can be clearly seen that when people touch the 220V charged body, the leakage protector will react quickly in 0.1 seconds. Without life-threatening.
(2) In the TN-CS or TN-S system, if the earth leakage fault is not installed, if the ground fault occurs, the equipment casing will generate a contact voltage that is dangerous to the human body; even if the earth leakage protector is installed, even if it occurs If the grounding fault occurs and the contact voltage has not reached the end of life, the leakage protector will immediately cut off the power circuit. The reason is: in the electrical design of the residential building, the designer has selected a rated operating current of less than or equal to 30 mA for the leakage protector installed by the user, and the operating time is 0.1 second. When a ground fault occurs, as long as the leakage current is generated, the leakage protector operates immediately when the leakage current is less than or equal to 30 mA, and the power supply circuit is cut off. At the same time, the current of 30 mA acts on the human body within 0.1 seconds to not endanger life safety.
(3) Installation of the leakage protector monitors the insulation level of the distribution line. If the device has a shell failure or insulation damage, a leakage current will occur. When the leakage current reaches the rated operating current of the leakage protector, the power circuit will be cut off immediately. That is to say, the faulty line has been cut off before the person has touched the dangerous contact voltage of the faulty device. Thus, the occurrence of electric shock and fire accidents is avoided in advance.
(4) In the event of a ground fault, the factor of disconnecting the fault is not dependent on overcurrent protection, but on leakage protection. Furthermore, the rated operating current value of the leakage protection is small, and the difference is 1000 to 10,000 times compared with the overcurrent. Therefore, the contact voltage appearing in the device casing is also very low, generally less than 50V, which greatly improves safety.