# Accuracy Tests of a Dual-Class Hybrid FBG/PZT Photonic Current Transducer Featuring a Novel Passive Autoranging Circuit

## TL;DR

This paper introduces a new photonic current transducer with an autoranging circuit that can meet both metering and protection-class requirements for the first time.

## Contribution

The novel passive autoranging circuit enables the PCT to satisfy metering and protection-class standards simultaneously.

## Key findings

- The PCT with the passive AR circuit significantly extends the dynamic range of the device.
- The sensor reduces current-measurement errors and operates correctly across an extended range.
- The design supports remote interrogation and multiplexing of multiple sensors.

## Abstract

This paper reports, for the first time, the characterization and measurement accuracy evaluation of a photonic current transducer (PCT) featuring a hybrid fiber Bragg grating/piezoelectric transducer (FBG/PZT) and an integrated passive autoranging (AR) circuit. The enhanced sensor is designed to meet both metering-class (0,2 S) and protection-class (5P15) requirements simultaneously—capabilities not yet demonstrated by any other device in the industry that also supports remote interrogation and multiplexing of multiple sensors. The autoranging technique employs MOSFET switches to dynamically adjust the burden resistance, preventing FBG/PZT voltage saturation during fault or thermal-current events while maintaining adequate sensitivity at lower currents. Experimental results show that integrating the PCT with the passive AR circuit significantly extends the device’s dynamic range, reduces current-measurement errors, and demonstrates potential compliance with both 0,2 S metering- and 5P15 protection-class requirements. The results also confirm that the sensor operates correctly across this extended range.