DL-LX26AL series of zero sequence current transformer residual current detection, electrical fire monitoring

The function and working principle of zero sequence current (residual current / leakage current) transformer:
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Two abnormal phenomena occur when the electrical equipment leakage:
First, the balance of the three-phase current is destroyed, there is zero sequence current;
The two is that when the normal non charged metal casing appears on the ground voltage (normal, the metal shell and the earth are zero potential).
The zero sequence current transformer is the leakage protection device through the zero sequence current transformer detection to obtain abnormal signals, through the intermediate mechanism to transfer, so that the implementation of the action, through the switch device to disconnect the power supply.
The structure of the current transformer is similar to that of a transformer. It is composed of two coils that are insulated from each other on the same core. When a coil has a residual current, the two coil induces an electric current.
The zero sequence current transformer installed in the line, a coil with the grid lines connected to and in the secondary coil and the leakage protector tripping device connection.
When the normal operation of the power equipment for electric water heaters, and line current is equilibrium, transformer current vector and zero (current is the direction of the vector, such as according to the direction of the outflow for "+", return direction "-", back and forth in the transformer current are equal in magnitude, in the opposite direction, plus or minus offset each other). Since there is no residual current in a coil, so not secondary induction coil, switch device for earth leakage protection device in closed state operation.
When electric leakage electric water heater equipment shell and human touch in a timely manner, at the fault point shunt, this leakage current by human - earth grounding, return to the transformer neutral point (not the current transformer), resulting in transformer Shen into, out of the current appeared imbalance (current vector and is not zero), a secondary coil Shen residual current. Therefore, secondary induction coil, when the current value reaches the value of the action current of the leakage protector is defined, automatic switch trip, cut off the power supply.