Three-phase five-wire refers to: three phase wires, one ground wire and one zero wire.
The three phase wires are phase A, phase B and phase C respectively.
One ground wire is denoted by PN,
one zero wire is denoted by N.
Three-phase five-wire has one more ground wire than three-phase four-wire. The zero wire is the working zero wire, which is needed to form a circuit with the phase wires, and the ground wire is grounded in any case, and often has to be repeated several times to ground. The equipment enclosure is grounded through the ground wire to ensure that the enclosure of the equipment is not energized. In a power transmission and electricity circuit, grounding is not once, many times grounded to ensure that the equipment shell, the appliance shell must be grounded to increase the safety of electricity.
Expanded information:
The five wires in the three-phase, five-wire system refers to: three phase wires plus a ground wire A zero wire. General use of the most widely used low-voltage power transmission is the three-phase four-wire system, using three phase line plus zero line power supply, zero line from the transformer neutral point and ground, the voltage is 380/220V, take any one phase line plus zero line constitutes a 220V power supply line for the general family, the voltage between the three phase lines is 380V, generally used for the motor.
Three-phase five-wire system than the three-phase four-wire system more than one ground, for higher safety requirements, equipment requirements for a unified grounding places.
Three-phase five-wire system of learning lies in the two "zero" on the grid in the more sophisticated electronic instruments, if the zero line and the ground line *** with a line, then, for the circuit of the work of the zero point will have an impact, although theoretically, they are all 0 potential point, if there is occasionally a surge of impulse impact to the work of the zero line, while the zero line and the ground line is not separated, for example, such as this impulse! But because of the phase line leakage caused by, and then some electronic circuits, if the zero drift phenomenon is serious, then the shell of the appliance may be electrically charged, may damage the electrical components, and even damage to electrical appliances, resulting in a risk of personal safety.
The fundamental difference between the zero line and the ground line is that one constitutes a working circuit, a protective role is called protective grounding, a back to the grid, a back to earth, in electronic circuits, the two concepts are to be differentiated, in the regular company, the two wires are required to be connected separately.
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