Have to look at the current transformer wiring diagram

We use the function to divide the current transformer into two kinds: measuring current transformer and protection current transformer. The principle of various current transformers is similar. This paper summarizes the wiring diagrams of various current transformers for reference.

A measuring current transformer wiring method

The role of the current transformer for measurement is to provide grid current information to measurement and metering devices within the normal voltage range.

1 ordinary current transformer wiring diagram

The primary current of the current transformer enters from the P1 terminal and comes out from the P2 terminal; that is, the P1 terminal is connected to the power supply side, and the P2 terminal is connected to the load side.

The secondary current of the current transformer flows out from S1 and enters the positive terminal of the ammeter. After the negative terminal of the ammeter comes out, it flows into the secondary terminal S2 of the current transformer. In principle, the S2 terminal is grounded.

Note: Certain current transformers are nominal at one time, L1, L2, and secondary side nominal K1, K2.

2 through-heart type current transformer wiring diagram

The core-type current transformer wiring is similar to the common current transformer. The primary side passes through the P1 face of the transformer, and the P2 face comes out. The secondary side connection is the same as the common transformer.

Two current transformer wiring diagram

Current transformer wiring is generally divided into four wiring modes:

1. Single current transformer wiring diagram

Can only reflect the situation of single-phase current, suitable for the need to measure the current of a phase.

Single current transformer wiring diagram

2. Three-phase complete star connection and delta connection current transformer connection diagram

Three-phase current transformer can accurately understand the three-phase load changes in a timely manner.

Three-phase complete star current transformer wiring diagram

Three-phase complete angular current transformer wiring diagram

3. Two-phase incomplete star wiring form current transformer wiring diagram

It is used most in practical work, but it is limited to three-phase three-wire systems. It saves one current transformer and calculates the phase B current using the currents of phase A and phase C according to the principle of three-phase vector sum and zero.

Two phase incomplete star wiring form current transformer wiring diagram

4. Two phase difference current wiring form Current transformer wiring diagram

It is also used only for three-phase three-wire circuits. The advantage of this type of connection is that it not only saves one current transformer, but also one relay can be used to reflect various phase-to-phase short-circuit faults in the three-phase circuit, that is, to complete three with the least number of relays. Phase overcurrent protection saves investment.

Two phase difference current connection type current transformer wiring diagram

5. Other wiring methods

5.1 primary side serial, secondary side serial

Current transformer primary side series, secondary side series wiring diagram as shown below, after the series effect: Transformer ratio unchanged, the secondary rated load increases by a factor of two.

Current transformer primary side series, secondary side series wiring diagram

5.2 Primary side parallel and secondary side parallel

Current transformer primary side series and secondary side parallel connection diagram are shown below. After serial and parallel connection, the transformer transformation ratio is reduced by a factor of two and the secondary rated load is increased by a factor of two.

Current transformer primary side series, secondary side parallel connection diagram

5.3 Primary Parallel Connection and Secondary Parallel Connection

Current transformer primary side parallel connection, secondary side series connection diagram as shown below, series and parallel effect: Transformer ratio doubled, secondary rated load doubled.

Current transformer primary side parallel, secondary side series wiring diagram

5.4 Primary parallel and secondary parallel

Current transformer parallel connection of primary side and parallel connection of secondary side is shown below. After parallel connection, the transformation ratio of transformer is unchanged and the secondary rated load is doubled.

Current transformer primary side parallel, secondary side parallel connection diagram