Fiber optic current transducer（FOCT）overcomes the weakness of electromagnetic current transducer in transient response

insulation and other performances

and meets the demands of accurate current measurement real-timely in modern power system.To ensure low failure and high reliability of fiber optic current transducers（FOCT）

it is urgent to study methods of condition monitoring and fault diagnosis in FOCT.Faults in FOCT have statistical characteristics.With analyzing of time domain and frequency domain features in fiber optic current transformers’ measurement data

we establish correspondence between the physical characteristics of key components in transformer and data features

then

build diagnostic analysis model based on Allan variance.According to the Allan variance calculation results

we can diagnose fiber optic current transformer’s health state

and realize faults location.Experiment results show that diagnostic methods based on Allan variance are accurate and effective to identify fault features

diagnostic operation status

and online monitor

without additional hardware equipment and power off.

transformers no power outages

no off-grid conditions

the realization of electronic transformer online monitoring and condition diagnosis.