What is protection zero? what is the function? -Solutions - Huaqiang Electronic Network

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The protection zero is abbreviated as zero connection, which is to connect the metal parts (housing) of the electrical equipment under normal conditions without wires, and connect the wires directly to the neutral line of the low-voltage distribution network (neutral line) to protect personal safety and prevent occurrence. Electric shock accident.

Protection and zero connection generally cooperate with fuses, trip units, etc., as a low-voltage neutral point direct grounding system and 380/220 volt three-phase four-wire system (referred to as TN-C system in the IEC standard) .

With protection zero, when a short circuit occurs, the short-circuit current flows from the phase line to the neutral line and back to the neutral point of the transformer. Since the resistance and reactance of the fault circuit are very small, the fault current is large enough to make the protection device (fuse or automatic switch) on the line act quickly, thereby disconnecting the leakage device from the power supply, eliminating the danger and protecting it. effect.

Although the protection grounding and the protection zero can ensure personal safety, the protection zero is more advantageous than the protective grounding, because the impedance of the neutral line is small and the short-circuit current is large, thus overcoming the limitation that the protection grounding requires a small resistance value. .