Three-phase electricity meters are divided into three-phase three-wire meters and three-phase four-wire meters. There are three main wiring methods: direct access, current transformer wiring, and current and voltage transformer wiring. The wiring principle of a three-phase meter is generally: connect the current coil in series with the load, or connect it to the secondary side of the current transformer, and connect the voltage coil in parallel with the load or connect it to the secondary side of the voltage transformer.
Three-phase four-wire system, in the low-voltage distribution network, the transmission line generally adopts the three-phase four-wire system, of which three lines represent A, B, C three-phase, and the other is the neutral line N or PEN (if the loop power supply If the neutral point of the side is grounded, the neutral line is also called the neutral line (the old name should be gradually avoided and renamed as PEN. If it is not grounded, the neutral line cannot be called the neutral line in a strict sense).
In the single-phase transmission line entering the user, there are two lines, one is called the phase line L, and the other is called the neutral line N. The neutral line normally passes current to form the current loop in the single-phase line. In the three-phase system, when the three phases are balanced, the neutral line (zero line) has no current, so it is called a three-phase four-wire system; in the 380V low-voltage distribution network, in order to obtain the 220V phase-to-phase voltage from the 380V phase-to-phase voltage Set the N line, and in some occasions, it can also be used for zero-sequence current detection, so as to monitor the balance of the three-phase power supply.
Three-phase four-wire meter wiring diagram
Post time: Nov-26-2022