ABB SPAJ140C Combined Overcurrent and Earth Fault Protection Relay

Key Features and Functional Highlights

• Dual Protection Elements: Integrates a three-phase overcurrent protection unit (50/51) and a sensitive earth fault protection unit (50N/51N) in one device, providing complete coverage for radial feeders.
• Flexible Time-Current Characteristics: Supports both Inverse Definite Minimum Time (IDMT) and Definite Time characteristics. Users can select from standard curves (Normal Inverse, Very Inverse, Extremely Inverse, Long Time) compliant with IEC 60255 and BS 142 standards, or set instantaneous high-set tripping for rapid fault clearance.
• Advanced Fault Detection: Includes specialized logic for Broken Conductor Protection, detecting open-circuit conditions that standard overcurrent relays might miss. It also features built-in Circuit Breaker Failure Protection (CBFP) to initiate backup tripping if the primary breaker fails to operate.
• Self-Powered Operation: Capable of drawing operating power directly from the Current Transformers (CTs), eliminating the need for an external auxiliary power supply in many installations and enhancing system reliability.
• Comprehensive I/O and Logic: Equipped with two heavy-duty output relays for tripping and four signal relays for alarms or indication. Features a programmable output matrix that allows users to route protection signals to specific outputs based on custom logic.
• Digital Communication and Monitoring: Supports robust industrial communication protocols including RS-485, Modbus RTU/ASCII, and IEC 61850 (via gateway modules). This enables remote parameter setting, real-time data acquisition, and integration into SCADA or DCS systems.
• User-Friendly Interface: Features a high-contrast display (LED or LCD depending on revision) and front-panel push buttons for local viewing of measurements, fault records, and setting adjustments without external software.
• Continuous Self-Supervision: The relay continuously monitors its internal electronics, power supply, and communication status. If an internal fault is detected, it triggers an alarm and blocks unnecessary tripping to prevent nuisance outages.

Technical Specifications

• Product Family: SPA Series / SPACOM Distribution Automation
• Protection Functions:
  • Phase Overcurrent: Three-stage protection (Low set I>, High set I>>) with independent time delays.
  • Earth Fault: Sensitive residual current protection (Low set I>N, High set I>>N) with directional or non-directional options.
  • Auxiliary Functions: Broken conductor detection, Breaker Failure Protection (CBFP), Cold Load Pickup logic.
• Input Specifications:
  • Current Input: 1 A or 5 A nominal (CT secondary), selectable via wiring or software.
  • Voltage Input: Optional auxiliary voltage supply (24–250 V DC/AC) for metering and logic power.
• Operating Parameters:
  • Current Range: Continuous operation up to 120% of nominal; tripping accuracy typically ±2% or ±5ms.
  • Time Settings: Adjustable from 0.05 seconds to 30 seconds for definite time; variable curves for inverse time.
• Output Contacts:
  • Tripping Relays: 2 x Changeover contacts (SPDT), rated for high breaking capacity (typically 8A at 250V AC).
  • Signal Relays: 4 x Changeover contacts for alarm/indication.
• Environmental and Mechanical:
  • Enclosure: IP40 front panel (finger-safe), suitable for switchgear mounting.
  • Operating Temperature: -25°C to +55°C (Storage: -40°C to +85°C).
  • Dimensions: Standard 96 mm x 96 mm cutout (DIN rail or panel mount).
  • Weight: Approximately 0.8 kg to 1.0 kg.
• Standards Compliance: IEC 60255, IEC 61000-4 (EMC), CE, UL, CSA.

Application Scenarios

The ABB SPAJ140C is a versatile workhorse deployed across various sectors where reliable medium-voltage protection is essential:

• Utility Substations: Used as the primary protection for 10kV to 36kV distribution feeders, ensuring selective tripping to isolate faults without affecting the entire grid.
• Industrial Power Systems: Protects transformers, large motors (up to 1500kW), and capacitor banks in heavy industries like steel mills, cement plants, and chemical processing facilities.
• Infrastructure and Buildings: Ideal for terminal substations in commercial complexes, airports, and data centers, providing backup protection for incoming power lines.
• Renewable Energy: Applied in wind farm collector systems and solar park substations to protect cable feeders and step-up transformers.
• Marine and Railway: Utilized in shipboard electrical distribution boards and traction power supply systems for electric trains due to its high vibration resistance and compact size.
• Radial Networks: Specifically designed for solidly grounded, resistance grounded, or impedance grounded systems where selective, time-graded protection is required.

Ordering and Configuration Information

When specifying or ordering the ABB SPAJ140C, attention to detail is crucial as the part number defines the exact hardware configuration:

• Part Number Structure: The full identifier (e.g., SPAJ140C-AA or 133550) typically includes codes for the protection module type, current rating, and firmware version.
• Current Rating Selection: The relay must be ordered with the correct nominal current input (1A or 5A) to match the installation’s Current Transformers. This is often a hardware jumper or wiring configuration on the terminal block.
• Auxiliary Supply: While self-powered for protection logic, an auxiliary supply (24-250V DC/AC) is often required for metering, external communication modules, and backlighting.
• Communication Modules: For IEC 61850 or fiber optic communication, additional plug-in modules (such as SPA-ZC series converters) are required and must be ordered separately.
• Accessories: Common accessories include test blocks, front-panel covers, and specialized test software (CAP501/CAP505) for PC-based configuration and event log analysis.

Maintenance and Diagnostics

The SPAJ140C is designed for low maintenance but requires periodic verification:

• Self-Monitoring: The relay’s built-in diagnostics will flag issues like CT circuit open circuits, internal RAM/ROM errors, or power supply anomalies via the front panel LEDs or communication bus.
• Testing: Features a dedicated “Test” button to verify the integrity of the tripping circuit. Comprehensive testing requires a secondary injection test set to simulate fault currents and validate the time-current curves.
• Event Recording: The relay stores the last several fault events, including the fault type, magnitude, and timestamp, which can be retrieved locally or remotely for post-fault analysis.