Relay Protection Sensitivity Test Report

A Relay Protection Sensitivity Test Report documents the verification of a protection relay's ability to detect internal faults accurately and operate reliably under specified conditions.Purpose of Sensitivity TestingSensitivity testing ensures that the protection relay responds correctly to internal faults within the protected zone while remaining stable under external or through-fault conditions. It confirms that the relay can detect minimal fault currents and operate without misoperation due to CT wiring errors or system transients .Test ObjectivesVerify correct relay operation before and after commissioning .Confirm the relay's sensitivity to internal faults within the protected zone .Check CT polarity and wiring connections to ensure proper differential current measurement .Validate stability under through-fault conditions and during abnormal system events .Test broken-wire monitoring and relay blocking functions for safety .Test MethodsPrimary Injection Test: Large currents are injected directly into the CT circuits to simulate real fault conditions. The minimal primary current required to operate the relay is determined, and the relay's response is recorded .Secondary Injection Test: Controlled currents and voltages are injected into the relay inputs to simulate fault conditions without energizing the primary system. This method is used to verify pickup, drop-off, and sensitivity .Polarity and Differential Checks: Currents are injected with one CT reversed to ensure the relay detects differential currents correctly. Zero differential current indicates proper CT wiring and stability .Broken-Wire Simulation: Interruptions in CT secondary circuits are simulated to verify that the relay blocks differential protection and issues appropriate alarms .Test EquipmentPrimary Injection Test Kit for high-current testing .Secondary Injection Test Kit for controlled voltage and current inputs .Digital relay interfaces (e.g., DIGSI for SIPROTEC relays) to read measurement values .Portable multi-phase relay test sets for manual or automated testing .ReportingA comprehensive Relay Protection Sensitivity Test Report typically includes:Test date, location, and relay identification.Test setup and equipment used.Injected current and voltage values, including minimal operating currents.Observed relay operation, pickup, and drop-off points.CT wiring verification and polarity checks.Any anomalies or deviations from expected performance.Conclusions confirming whether the relay meets sensitivity and stability requirements .Standards and ReferencesTesting is performed in accordance with international standards such as IEC 60255, IEEE C37 series, and manufacturer-specific procedures for digital relays . These standards ensure consistency, safety, and reliability in protection system commissioning and maintenance. This report serves as a formal record for commissioning, maintenance, and regulatory compliance, providing assurance that the protection relay will operate correctly under fault conditions and maintain system stability.