What should be paid attention to when leakage protector is used?

(1) the leakage protector is suitable for the low voltage power distribution system which is grounded directly or indirectly through the resistance and reactance. The leakage protector is not suitable for the system with ungrounded neutral. Because the latter does not constitute a leakage electric circuit, even if the ground fault occurred, the greater than or equal to the rated current of the leakage protective device, the protective device can not be timely action to cut off the power supply loop; or rely on the human body can meet the fault point to a leakage electric circuit, furtherimproved leakage protector, cut off the power supply circuit. But it's still unsafe for the human body. Obviously, must have the grounding device conditions, electrical equipment leakage occurs, and when the leakage current reaches the action current, you can immediately trip within 0. seconds, cut off the main circuit of the power supply.

(2) the neutral line N of the protection circuit of the leakage protector should pass the zero sequence current transformer. Otherwise, after the connection, there will be an unbalanced current to make the leakage protector misoperation.

(3) the zero connection protection line (PE) is not allowed to pass zero sequence current transformer. Because the protection line (PE) passes the zero sequence current transformer, the leakage current passes through the PE protection line and then passes through the zero sequence current transformer, which causes the current to cancel, and the transformer does not detect the leakage current value. When the fault occurs, the leakage protector does not act, and can not play a protective role.

(4) the working neutral line of the control circuit can not be repeatedly grounded. On the one hand, when the earth is repeatedly grounded, a part of the work current will return to the neutral point of the power supply by repeated grounding in the normal working condition, and the unbalanced current will appear in the current transformer. When the unbalance current reaches a certain value, the leakage protector will produce misoperation; on the other hand, due to the fault current, leakage current line protection may also through the current transformer power supply line back to the neutral point of personality, to offset the leakage current of the transformer and the protector to action.

(5) the neutral line N and the protective line (PE) behind the leakage protector can not be combined into one. If the two are merged into one, when the leakage fault or human shock, leakage current through the current transformer backflow, the results are similar to the situation (3), resulting in leakage protection device refused to move.

(6) the lines between the protected electric equipment and the leakage protector can not be touched each other. If the line between the collision or zero line handover, will immediately destroy the balance of the zero sequence current value, caused by the malfunction of leakage protector; in addition, the protected electrical equipment can be installed in parallel after the leakage protector, wiring to ensure correct, nor will the electric equipment connected to the wiring test button.

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