Optically powered air core current transformer applied in circuit breaker is reported in several aspects including the theory

the structure and the properties.By using the optical fiber

the signals are transmitted between the high voltage side and ground

and source power is supplied to high voltage side.The insulation structure of current transformer is comparatively simple

and the area and cubicle occupied by the facility will decrease while the air-core current transformer is combined with the breaker.Without hand-making and resistance adjustment

a new structure of air-core coil

based on printed circuit boards

is adopted by the transformer.Type test results show that when the rated current varies from 20 A to 3 000 A

the accuracy of air core current transformer meets 0.2S class for metering and 5P20 for protection.