Field Testing Challenges and Innovations for LPITs in Relay Protection Systems

The integration of Low Power Instrument Transformers (LPITs) into medium and high-voltage switchgear marks a significant advancement in relay protection systems. Offering notable advantages over conventional instrument transformers, such as reduced size, absence of saturation, and enhanced safety, LPITs are becoming increasingly prevalent. This paper explores the challenges and innovations in field-testing protection systems equipped with LPITs. Unlike traditional systems, LPITs do not utilize standard 1A/5A and 100V/110V outputs, necessitating the development of specialized test kits that accommodate LPIT-specific analog outputs. We detail the creation and application of a new secondary injection test kit designed to support LPITs effectively. Additionally, the paper discusses various testing methodologies that have been adapted to validate the functionality and accuracy of LPITs within operational settings. Our findings highlight the critical role of precise testing equipment and methodologies in ensuring the reliability and effectiveness of modern protection systems enhanced by LPIT technology.