The configuration principle of the voltage transformer is: it should meet the requirements of measurement, protection, synchronization and automatic device; ensure that the protection device does not lose pressure when the operation mode is changed, and the pressure can be conveniently taken on both sides of the synchronization point. Usually configured as follows:
1. Busbars The voltage transformers shall be installed on the three-phase of each group of main busbars of the voltage level of 6~220kV. The bypass busbars shall be determined according to the need of installing voltage transformers outside the loop outlets.
2. Line When there is a need to monitor and detect the presence or absence of voltage on the outside of the line breaker for synchronous and automatic reclosing, the side is equipped with a single-phase voltage transformer.
3. Generators Two sets are usually installed at the exit. One set (three single-phase, two-winding △/Y wiring) is used to automatically adjust the excitation device. One set is used for measuring instrument, synchronous and relay protection. The voltage transformer adopts three-phase five-column or three single-phase grounding special transformers, which are connected to Y0/Y0/△ wiring, and the auxiliary winding is connected into an open triangle. For insulation monitoring. When the transformer load is too large, a set of transformers with incomplete star connection can be added, which is specially used for measuring instruments. A neutral phase point of 50 MW and above generators is also often equipped with a single-phase voltage transformer for 100% stator grounding protection.
4. Transformer The low-voltage side of the transformer is sometimes equipped with a set of voltage transformers to meet the requirements of synchronous or relay protection.
5. Voltage transformer configuration of 330~500kV voltage level: When double busbar wiring, install on each return line and three sets of busbars. When one and a half circuit breakers are connected, they are installed on each three-phase of the outgoing line. The main transformer incoming line and each group of busbars are installed on one phase or three phases according to the requirements of relay protection devices, automatic devices and measuring instruments. The secondary circuit of the voltage transformer of the line and the busbar does not switch.www.ctsensorducer.com/