The voltage transformer is designed to convert high voltage into a standard secondary voltage of 100V or lower in proportion for protection, measurement, and instrumentation. It effectively isolates high voltage from operators to ensure safety.

Operating on the principle of electromagnetic induction, its structure is the inverse of a current transformer. The secondary circuit is high-impedance, where the current magnitude is determined by the circuit's impedance. As secondary load impedance decreases, the secondary current increases, causing a corresponding increase in the primary current to maintain electromagnetic balance.