A high accurate electronic instrument transformer calibration system is introduced in this paper. The system uses the fourth-order convolution window algorithm for the error calculation method. Compared with Fast Fourier Transform, which is recommended by standard IEC-60044-8 (Electronic current transformers), it has higher accuracy. The relative measuring errors caused by asynchronous sampling could be reduced effectively without any special hardware technique adopted. The results show that the ratio error caused by asynchronous sampling can be reduced to 10 -4, and the phase error can be reduced to 10 -3 degrees when the deviation of frequency is within ±0.5 Hz. The present method of measurement processing is achieved by a high-accuracy USB multifunction data acquisition (DAQ) card and virtual measurement devices, with low cost, short exploitation period and high stability.

Compared with other kinds of electronic instrument transformers, the All Fiber-Optic Current Transformer (FOCT) have the advantages of high accuracy, wide dynamic range , strong ability to resist electromagnetic interference environment, simple and flexible of installation. But because of the short-time application, the operation reliability of FOCT can't be assessed base on the operational log we have now. According to this situation, the study on the structure and work environment had been done, in order to find the main environment parameter which affect on the aging of FOCT.Then the accelerated aging tests had been done on the components of a FOCT such as photo detector, optical source and optical phase modulator Then the mean time between failures (MTBF) of these components had been estimated base on the results of aging tests. Finally we can assess the operation reliability of FOCT. The results indicated that the MTBF of SLD light source is shorter than other Optical Components in the current transformer which was studied on . And dual-redundant design could be used to increase the MTBF of optical sensor parts. Thus the MTBF of this all-optical current transformer could satisfy the requirement of 30 years long-term stable operation of instrument transformers. Index Terms-All Fiber-Optic Current Transformer (FOCT) operation reliability, accelerated aging test, mean time between failures (MTBF) Optical Components