The method of current transformer wiring

(1) Current sensor wiring. This wiring method is used to accurately measure single-phase load current or load balance in a three-phase power supply system.

(2) Star connection consisting of three current sensors. This wiring scheme is used to accurately measure unbalanced three-phase currents in load-balanced or three-phase power systems. The power supply circuit of the relay protection device configured by the star connection system can ensure the sensitivity and reliability for common faults such as three-phase, two-phase short circuit and single-phase grounding short circuit.

(3) The star connection consisting of two current inductors is incomplete. This wiring method is widely used for grounding protection of 6-10kV neutral line. The current rate on the instrument panel of the common transmission line corresponds to the phasor of the U-phase and W-phase currents, that is, the power supply circuit of the relay protection device adopts the two-phase incomplete star connection method, which can maintain various two-color short-circuit common faults, but the sensitivity Unlike the three-phase complete star connection. It is less sensitive than the wiring method. Compared with the three-phase all-star wiring method, the secondary mechanical equipment is reduced by 1/3, saving the project investment cost.

(4) Two-phase current difference wiring composed of two current inductors. The power supply circuit of the relay protection device generally adopts this wiring method. For example, common faults such as overflow protection of lines and motors, side differential protection of series power capacitors, etc., various two-color short-circuit faults can be reflected, but the sensitivity is different.