The inlet cabinet current transformer represents 2CT, the metering cabinet voltage transformer represents Y-Y wiring, the voltage transformer of the voltage transformer cabinet represents Y-Y-open delta wiring, and the name of the metering cabinet and the voltage transformer cabinet on the diagram is reversed.
The current transformer consists of a closed core and windings. It has a primary side winding with few turns and is strung in the line of the current to be measured. Thus it often has the full current of the line flowing through it, and the secondary side winding turns are more, strung in the measuring instruments and protection circuits.
Current transformer in operation, its secondary side of the circuit is always closed, so the measuring instrument and the protection circuit series coil impedance is very small, the current transformer operating state is close to a short circuit.
Expanded information:
Voltage transformer precautions
1, voltage transformer in the operation of the project in accordance with the provisions of the regulations before the test check. For example, measuring polarity, connecting groups, shaking insulation, nuclear phase sequence.
2, voltage transformer wiring should ensure its correctness, the primary winding and the measured circuit is connected in parallel, the secondary winding should be connected to the measuring instrument, relay protection device or automatic device voltage coil in parallel, at the same time, pay attention to the correctness of the polarity.
3, connected to the secondary side of the voltage transformer load capacity should be appropriate, connected to the secondary side of the voltage transformer load should not exceed its rated capacity, otherwise, it will make the transformer error increases, it is difficult to achieve the correct measurement.
Baidu Encyclopedia - Voltage Transformers
Baidu Encyclopedia - Current Transformers