Current transformer wiring diagram - Solutions - Huaqiang Electronic Network

Probe current voltage pin 420*4450 head diameter 5.0 over current current and voltage pin

Photocoupler

The current transformer wiring diagram is as follows:

• Figure 1 and Figure 2 show the wiring of three current transformers.
• Figure 3 shows the wiring of two current transformers.

According to the equation: Ia + Ib + Ic = 0, it can be derived that Ia + Ic = -Ib. Therefore, the green ammeter indicates the B phase current.

Figure 1

Figure 2 & Figure 3

In a three-phase system, the K1 terminals of the current transformers are connected to any of the ammeter terminals, while the other ends of the ammeters are connected to the K2 terminals and grounded or connected to zero.

The wiring method of current transformers is selected based on the operational requirements of the load they are connected to. The most common configurations include single-phase, three-phase star, and incomplete star connections.

1. Three-phase full star connection accurately reflects the true current in all three phases. This configuration is commonly used in large current grounding systems for protection against three-phase, two-phase, and single-phase ground faults.

2. Two-phase two-relay incomplete star connection allows accurate measurement of the current in two phases. It is typically used in small current grounding systems with a neutral point of 6–10 kV for protection against three-phase and two-phase short circuits.

Full star connection

Two-phase two-relay incomplete star connection

3. Two-phase difference connection reflects the difference between the currents of two phases. This method is applied in small current grounding systems (6–10 kV) for protection against three-phase, two-phase short circuits, and for protecting small motors and transformers.

Two-phase difference connection

4. Single-phase wiring is used in three-phase current balance scenarios, where a single-phase current can represent the overall three-phase current. This is mainly used in measurement circuits.

Single-phase wiring

5. In a two-phase three-relay complete star connection, the third relay receives a current equal to Ij = Iu + Iw = -Iv. This configuration is used in large current grounding systems for protection against three-phase and two-phase short circuits.