Leakage protector rated leakage current selection - Database & Sql Blog Articles

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It is very important to correctly and reasonably select the rated leakage current of the leakage protector: On the one hand, the leakage protector can selectively act when the electric shock or leakage current exceeds the allowable value; on the other hand, the leakage protector under the normal leakage current It should not be operated to prevent unnecessary power loss caused by power interruption.
The rated leakage current of the leakage protector should meet the following three conditions:
(1) In order to ensure personal safety, the rated leakage current should not exceed the safe current value of the human body. Internationally recognized that 30 mA is the safe current value of the human body;
(2) In order to ensure reliable operation of the power grid, the rated leakage current should escape the normal leakage current of the low voltage grid;
(3) In order to ensure the selectivity of multi-stage protection, the rated leakage current of the next stage should be less than the rated leakage current of the previous stage, and the rated leakage current of each stage should have a step difference of 112 to 215 times.
The first stage leakage protector is installed at the outlet of the low voltage side of the distribution transformer.
The line protected by this level is long, the leakage current is large, and the rated leakage current is not more than 100mA when there is no perfect multi-level protection. When the multi-stage protection is perfect, the leakage current is small, the non-rainy season is 75mA. The rainy season is 200 mA; the grid with large leakage current is 100 mA in the non-rainy season and 300 mA in the rainy season.
The second-stage leakage protector is installed at the branch line exit, and the protected line is short, the power consumption is small, and the leakage current is small. The rated leakage current of the leakage protector should be between the rated leakage current of the upper and lower protectors, generally 30 to 75 mA.
The third-level leakage protector is used to protect single or multiple powered devices and is a protection device that directly prevents personal electric shock. The power consumption of the protected line and equipment is small, and the leakage current is small. Generally, it does not exceed 10 mA. It is recommended to use a leakage protector with a rated operating current of 30 mA and an operating time of less than 011 s.