Description

ABB SPAJ140C-AA Combined Overcurrent & Earth Fault Numerical Protection Relay

Technical Specifications

• Product Model: SPAJ140C-AA
• Brand: ABB
• Warranty: One Year
• Input Voltage: Auxiliary supply 80–265V AC/DC universal control power
• Operating Temperature: -10°C to +55°C
• Storage Temperature: -40°C to +85°C
• Response Time: High-set instantaneous trip ≤10ms fault detection latency
• Protection Class: IP40 front panel protection, panel flush mount / DIN rail mounting
• Accuracy Class: IDMT curve timing tolerance ±1% per IEC standard, CT input 1A/5A selectable
• Output Frequency: Rated 50Hz / 60Hz power system frequency adaptive
• Rated Current Range: CT thermal withstand 20A continuous (5A version), 500A 1-second short-time withstand
• Communication Interface: RS485 serial port, front LCD local HMI, PCM600 software configuration
• Supported Protocols: Modbus RTU, ABB SPACOM proprietary bus, IEC standard IDMT protection curves
• Overload Capacity: Built-in CT overcurrent withstand, internal surge suppression, continuous electronic self-supervision
• Dimensions: 143mm (L) × 128mm (W) × 141mm (H)
• 

Product Overview

The SPAJ140C-AA is a legacy microprocessor-based combined overcurrent and non-directional earth fault protection relay belonging to ABB SPACOM protection family, designed for selective short-circuit and earth fault protection of radial medium voltage distribution feeders, distribution transformers and large industrial motors in power plants, substation and factory power distribution systemsABB Group. It integrates independent phase overcurrent unit and earth fault unit, each equipped with two-stage low-set delayed trip and high-set instantaneous trip logic, together with embedded circuit breaker failure backup protection to strengthen MV switchgear safety interlock.

It addresses core grid protection risks in traditional radial power networks, including lack of graded selective tripping leading to upstream breaker cascading tripping, missing sensitive earth fault detection for high-resistance ground faults, no backup protection when circuit breaker fails to open under fault conditions, and difficulty recording fault waveforms and historical trip events for post-fault analysis. Equipped with four standard IEC/BS IDMT inverse time curves, fault event memory, backlit 2-line LCD display and full EMC noise immunity design, the relay delivers stable, repeatable protection performance in dusty substation control rooms with temperature variation and high electromagnetic interference from switchgear and transformers.