Inspection of current transformer wiring
(1) In order to find out whether there are common faults such as disconnection and short-circuit fault on the secondary side of the current transformer, the wires connected to the phase A voltage terminal of the electric energy meter and the wire of the phase C voltage terminal can be disconnected successively. The discs should all rotate. If the disc does not rotate after the A-phase voltage is cut off, the current transformer C-phase disconnection or short-circuit fault is indicated: if the disc does not rotate after the C-phase voltage is cut off, it indicates the current transformer A-phase disconnection or short-circuit fault. Assuming that the field cosg value is close to 0.5 (rational), in order to prevent misdiagnosis, the phase C voltage can be used to substitute the phase A voltage connected to the electric energy meter when the other phase of the C voltage is disconnected. Indicate that there is no disconnection, short-circuit fault, etc. of the A-phase current.
(2) In order to distinguish whether the voltage transformer is connected reversely, the ammeter can be connected to the second side of the current transformer one after the other, and the measured current can be used to distinguish. For the star connection, when the voltage transformer is all in one phase When the optical rotation is reversed once or again, the middle phase current will be twice that of the other phase currents. If the optical rotation of the current transformer is all reversed, a vector diagram of the electric energy meter coordinated wiring must be made, which can be comprehensively distinguished.
(3) To distinguish whether the current transformer is grounded or not, it can be accurately measured with an ammeter. For accurate measurement, one side of the ammeter is connected to the ungrounded terminal of the voltage transformer, and the other end touches the secondary line of the current transformer. If the ammeter is marked as 100V, it indicates that the current transformer is grounded again. If the ammeter is marked as 0, it indicates that the current transformer is not grounded.
(4) Determine whether the grounding installation is right or not, and it can be accurately measured with an ammeter. Therefore, one terminal of the ammeter should be grounded. The wires of the same terminal should touch the current terminal of the electric energy meter. If the terminal is grounded and installed, the ammeter should be unmarked and the rotating speed of the electric energy meter’s disk is not damaged; suppose this connection If the terminal is not grounded, the ammeter is marked, and the rotation speed of the disk is also damaged.