How are current transformers installed and regulated?

1. The metal frame on which the current transformer is installed (such as the busbar frame in the distribution cabinet) must be solid, and the exposed metal part of the transformer shell must be reliably grounded.

2. Wire correctly according to the diagram in the instruction manual. The numerical markings on both ends of the wire should be clear, and the marking range should meet the requirements of the rules.
3. The same group of current transformers should be installed in the same direction to ensure that the positive direction of the primary and secondary circuit currents of the current transformer group is the same, and the nameplate can be observed as easily as possible.

4. Open circuit is not allowed on the secondary side of the current transformer. When only one secondary loop is used for the secondary round transformer, the other secondary loop should be short-circuited reliably.

5. Copper wire should be used for the secondary circuit conductor or cable. The cross section of the current transformer line conductor should not be less than 2.5mm2, and the cross section of the voltage transformer circuit conductor should not be less than 1.5mm2.

6. The first row at the outlet of the current transformer should select a dedicated current terminal, and the secondary winding not used by the current transformer should be short-circuited and grounded on the terminal board.

7. The secondary circuit conductors in the disc and cabinet should not have joints, and there should be no joints in the middle of control cables or conductors. If a joint is necessary, a stronger terminal should be used for the transition connection.
8. The polarity of the current transformer cannot be reversed, and the phase difference and phase difference should meet the requirements of the design and regulations. For the transformer wiring of differential protection, the current phasor diagram of both arms must be measured before putting it into operation to check the correctness of the wiring.

9. The wires of the secondary circuit should be arranged neatly and beautifully. The connecting screws between the wires and electrical components and terminal blocks must not be loose. The distance between the wires and the clamping point should meet the requirements of this rule.

10. The insulation of the secondary circuit to the ground should be good, and the voltage circuit and the current circuit should not be mixed.

11. The current and voltage circuits should be grounded at the secondary side outlet of the transformer. (Note: The secondary side of the low-voltage current transformer cannot be grounded. Since the insulation grades of the wires, watt-hour meters and transformers used for the low-voltage metering device are the same, the maximum voltage that can be tolerated is basically the same; when the other secondary windings are grounded, the entire device's The insulation level of the primary circuit is reduced, and it is easy to damage the insulation weakness of the energy meter or transformer (such as being struck by induction lightning). In order to reduce the damage caused by lightning strikes, it is best not to ground the secondary side.)

12. The current transformer should be installed in the complete distribution cabinet. This kind of current transformer is not installed on the body. Finally, check whether the installation wiring is correct.