Inspection of current transformer wiring

- Oct 28, 2020-

(1) In order to find out if 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, and the electric energy meter The discs should all rotate. If the disc does not rotate after the A phase voltage is cut off, it indicates that the current transformer phase C is disconnected or short-circuited. If the disc does not rotate after the C-phase voltage is cut off, it indicates that the current transformer A phase is broken or short-circuited. If the on-the-spot cosg value is close to 0.5 (rational), in order to avoid misidentification, the phase C voltage can be cut off and the phase A voltage connected to the electric energy meter can be replaced by the phase C voltage. If the electric energy meter has a significant flip, it also indicates There is no disconnection, short-circuit fault, etc. for phase A current.

(2) In order to distinguish whether the voltage transformer is reversely connected, 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 in one phase When the optical rotation is reversed once or again, the middle phase current will be twice the current of the other phases. If the optical rotation of the current transformer is reversed, the vector diagram of the electric energy meter must be made to distinguish it comprehensively.

(3) To distinguish whether the current transformer is a grounding device, it can be accurately measured with an ammeter. For accurate measurement, one side of the ammeter is connected to the terminal of the ungrounded device 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 means that the current transformer has no grounding device.

(4) When distinguishing whether the grounding device is appropriate, it can be accurately measured with an ammeter. Therefore, one terminal of the ammeter should be grounded. The wires of the other terminals are connected to the current terminal of the electric energy meter. If the terminal is a grounding device, the ammeter should be unmarked, and the rotation speed of the electric energy meter's disk is not harmed; if the terminal is grounded If the device is not grounded, the ammeter is marked and the speed of the disk is also harmed.https://www.ctsensorducer.com/