SYSTEM DESCRIPTION
Figure 14.4 illustrates a typical generator main connections system. The windings of the generator are star-connected. This star point is formed at the neutral end of the winding outside the generator. The generator transformer is normally wound as a delta at the low-voltage (LV) end and star at the high-voltage (HV) end. It consists of a three-phase transformer or three single-phase transformers. The HV terminals of the unit auxiliary transformers and the three-phase grounding (earth) transformers (if installed) are supplied from the main bus bar. This connection is known as a tee-off from the main bus bar.
The voltage on the main connections system is monitored for various reasons including synchronization, tariff metering, instrumentation, automatic voltage regulation, power system stabilization, and protection systems. The current is also monitored for various reasons including protection systems. Voltage and current transformers are installed as shown in Fig. 14.4 to take these measurements.