Current leakage protection circuit

  
Current leakage protection is currently the most used and best leakage protection device. Current leakage protector fork into electromagnetic and electronic two, two leakage pr
Current leakage protection circuit - schematic

otection zero sequence current transformer are used as the detection element, the use of electromagnetic leakage protection leakage tripping release as a judgment element. Automatic circuit breaker as the actuator. Electromagnetic leakage protection than the sensitivity of the electronic differential, generally limited to 30mA, vibration resistance is also poor, but the ability to withstand voltage and lightning withstand strong electric shocks, by the power supply voltage, ambient temperature was less affected. Electronic electric mattress protector is to be improved on the basis of electromagnetic leakage protection, based on the zero-sequence current transformer to detect weak leak telecommunications number after amplification by an electronic circuit, compare, and other plastic processing, electronic amplifying bribe trigger trip mechanism, then drive automatic circuit breakers disconnect the power. Woe to higher electronic electrical protection sensitivity, resistance to mechanical impact ability, but poor impact resistance to lightning, power supply voltage and its environmental performance are to a certain extent. Electronic single-phase current-leakage protection circuit shown in Figure 14-5 Typical. When there is no electrical current Zhan, zero-sequence current transformer TA primary current vector is zero, TA non-inductive current output, the thyristor VTH is not turned on, the trip does not act, the normal power supply to the load. When the leakage current occurs, TA - secondary current vector and is no longer zero. TA secondary coil to generate induced electromotive force, the electromotive force induced by the formation of trigger pulse trigger circuit voltage, the thyristor conduction VTH. AC 220V power supply voltage via the trip coil L, UR bridge rectifier, thyristor VTH anode, a cathode circuit coil L is energized to drive the leakage protection switch Qs action on the cut off the power, which played a Protective effect of preventing electric shock, reducing the chance of damage to the equipment. RV domain compressive resistance over voltage protection effect; SB button to test it and test circuit composed of the resistor Ri, both ends of the test circuit when connected to the conductor TA inputs and outputs of different phases, in order to press the SB, in TA flowing through a simulated ground fault current, check the leakage protection is normal.




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