ABSTRACT
Capacitive and inductive voltage sensors are mainly utilized in low-frequency electric measurements. This chapter discusses the capacitive and inductive measurement with large voltage ranges. The voltage to be measured can be reduced by means of capacitive dividers. Capacitive dividers are affected by temperature and frequency. Voltage transformers (VTs) have two different tasks: reduction in voltage values for meeting the range of normal measuring instruments or protection relays; and insulation of the measuring circuit from power circuits. VTs are composed of two windings—one primary and one secondary winding. The primary winding must be connected to power circuits; the secondary to measuring or protection circuits. Electrically, these two windings are insulated but are connected magnetically by the core. For extremely high voltage values, both capacitive dividers and VTs are normally used. The capacitive impedance must compensate for the effect of the transformer’s internal inductive impedance at the working frequency.
