A wavelength-encoded electrical current sensor for high voltage using ultra-bright green (525 nm) light-emitting diode (LED) transducer and plastic optical fibre (POF), linking to remote location, has been developed. The wavelength receiver is based on passive filtering by employing an OG530 edge filter. LEDs from three different manufactures were characterized in their optical chirp response range, aiming for a sensor resolution improvement. The sensor precision (stability) was improved against external perturbations on the POF link by using an in-line mode-scrambler. The environment temperature of the LED transducer was kept unchanged at ±2°C.