ABB SPAJ-144-C Combined Overcurrent and Earth-Fault Relay

Description

Isolating distribution network anomalies with multi-stage discrimination, the ABB SPAJ 144 C serves as a secondary micro-processor based protection relay connected directly to secondary current transformers. This protective instrument incorporates an independent three-phase overcurrent assembly alongside a non-directional earth-fault unit to safeguard radial feeders against severe phase short circuits, thermal overloads, and earth leakage paths. Functioning as an active node within modern substation automation layouts, the SPAJ 144 C provides serial communication options through dedicated bus interface modules, executing deterministic control tracking and fault monitoring to ensure localized grid stabilization.

Features

• Three-Phase Overcurrent Supervision: Integrates three independent measurement stages designated as I>, I>>, and I>>> to yield reliable time-delayed and instantaneous network trip profiles.
• Dual Ground-Fault Elements: Provides a highly sensitive low-set ground fault stage Io paired with an un-delayed high-set Io>> element for comprehensive ground return fault trapping.
• Phase Discontinuity Protection: Employs continuous mathematical calculation of the maximum-to-minimum current differential to detect single-phase conductor breakage and severe network unbalance.
• Standardized Inverse-Time Arrays: Embeds four independent IDMT time-current curve profiles conforming to international standard definitions plus unique structural RI and RXIDG inverse steps.
• Circuit-Breaker Failure Monitor: Incorporates a dynamic backup timer that initiates alternate upstream interrupter sequences if the local breaker mechanism fails to operate within 0.1 to 1.0 seconds.
• Internal Diagnostics System: Uses a continuous self-supervision mechanism with auto-diagnosis that tracks hardware validity, auxiliary voltages, and internal register health.

Applications

• Selective phase-to-phase and ground fault isolation on radial distribution feeders within utility networks.
• Earth-fault tracking inside isolated neutral networks and networks utilizing resistively earthed ground paths.
• Comprehensive transformer secondary bank backup protection and major heavy industry motor feeder monitoring.

Ordering Information

Technical Specifications

Connections and Interfaces

Installation Guidelines

• Flush Panel Mount Integration: Mount the module housing directly within a panel cutout measuring 129 mm x 139 mm (+1 mm margin allowance) according to standard dim100 parameters. Secure via flush brackets.
• Earthing Control Rules: Fasten a solid copper trace route from the module grounding anchor node to the control cabinet primary bus framework to mitigate high-frequency surge potentials.
• Current Loop Circuit Validation: Prior to module slot maintenance or replacement, ensure all connected external secondary current transformer circuits are fully shorted out locally using bridging assemblies to prevent damaging overvoltage induction.
• Optical Bus Termination: Attach appropriate SPA-ZC 17 or SPA-ZC 21 external connection accessories to the asynchronous serial terminal array on the back panel when incorporating the system node into a master fiber optic ring network.

Compliance and Certifications

• CE Marking according to the European Community Directive for EMC Compatibility
• IEC 255-5 Insulation, Dielectric, and Impulse Shock Design Verification Standard
• IEC 255-21-1 Mechanical Vibration Testing Compliance Class 1
• IEC 255-21-2 Shock and Bump Withstand Registry Class 1