The JDCF-66/JDCF-126 voltage transformer is used to convert high voltage into a standard secondary voltage of 100V or lower in proportion for protection, measurement and instrumentation. At the same time, the use of voltage transformers can isolate high voltage from operators. Although the voltage transformer is also a device that works on the principle of electromagnetic induction, its electromagnetic structure relationship is exactly the opposite of that of the current transformer.

The secondary circuit of the voltage transformer is a high-impedance circuit, and the magnitude of the secondary current is determined by the impedance of the circuit. When the secondary load impedance decreases, the secondary current increases, causing the primary current to automatically increase by a component to meet the electromagnetic balance relationship between the primary and secondary sides.