The following items should be paid attention to when using the leakage protector:
(1) Leakage protectors are suitable for low-voltage power distribution systems where the neutral point of the power supply is directly grounded or grounded through resistance and reactance. For systems where the neutral point of the power supply is not grounded, leakage protectors should not be used. Because the latter cannot constitute a leakage electrical circuit, even if a ground fault occurs and a rated operating current greater than or equal to the leakage protector is generated, the protector cannot act in time to cut off the power circuit; or rely on the human body to connect to the fault point to constitute a leakage electrical The circuit prompts the action of the leakage protector and cuts off the power circuit. However, this is still not safe for the human body. Obviously, it is necessary to have the conditions of the grounding device. When the electrical equipment leaks and the leakage current reaches the operating current, it can immediately trip within 0.1 seconds, cutting off the main circuit of the power supply.
(2) The working neutral line N of the protection circuit of the leakage protector must pass through a zero sequence current transformer. Otherwise, after switching on, there will be an unbalanced current that will cause the leakage protector to malfunction.
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(3) Connecting to the zero protection line (PE) is not allowed to pass through the zero sequence current transformer. Because when the protection circuit (PE) passes through the zero sequence current transformer, the leakage current passes through the zero sequence current transformer through the PE protection line, causing the current to be offset, and the leakage current value cannot be detected on the transformer. In the event of a fault, the leakage protector will not operate and fail to protect.
(4) The working neutral wire of the control circuit cannot be grounded repeatedly. On the one hand, when grounding is repeated, under normal working conditions, a part of the operating current returns to the neutral point of the power supply through repeated grounding, and an unbalanced current will appear in the current transformer. When the unbalanced current reaches a certain value, the leakage protector will malfunction; on the other hand, when leakage occurs due to a fault, the leakage current on the protection line may also pass through the individual line of the current transformer and return to the neutral point of the power supply to offset The leakage current of the transformer is reduced, and the protector refuses to operate.
(5) The working neutral line N and the protection line (PE) behind the leakage protector cannot be combined into one. If the two are combined into one, when there is a leakage fault or human body shock, the leakage current flows back through the current transformer, and the result is similar to the situation (3), causing the leakage protector to refuse to operate