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.
Similar structure and transformer of current transformer (CT) is composed of two mutually insulated winding coils on the same core composition. When the residual current of a primary coil, secondary coil will be induced current.
Will install zero sequence current transformer 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 equal, 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 of 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 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.
