1. The current transformer cannot be connected to the wrong phase, that is, the phase A current must be connected to the phase A voltage, B and C are the same;
2. The first and last ends of the current line of the current transformer cannot be wrong.
Extended reading-three-phase four-wire
Three-phase four-wire system. In the low-voltage distribution network, the transmission line of current transformers generally adopts three-phase four-wire system, three of which represent A, B, C three phases, and the other is neutral N or PEN (if it is a loop Power supply) When the neutral point on the side is grounded, the neutral line of the current transformer is also called the neutral line (old name, should be gradually avoided, renamed to PEN. If there is no ground, the neutral line is strictly not Called neutral.) 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 usually forms a current circuit through current. Single phase line. In the system, when the three-phase balance, the neutral line (neutral) of the current transformer is currentless, so it is called three-phase four-wire system; in the 380V low-voltage distribution network, in order to obtain 220V from the 380V line voltage Phase voltage, set N line. In some cases, zero-sequence current detection can also be performed to monitor the three-phase power balance.