Description
ABB SPAJ140C Product Description
Product Overview
ABB SPAJ140C is a combined overcurrent and earth-fault protection relay belonging to the ABB SPACOM protection relay family. It is designed for selective short-circuit and earth-fault protection of medium-voltage distribution networks, particularly radial feeders. The relay integrates three-phase overcurrent protection with non-directional earth-fault protection and incorporates circuit-breaker failure protection, allowing multiple protection functions to be handled within a single numerical relay.
The ABB SPAJ140C continuously measures the three phase currents and residual/neutral current through current transformers. When a configured protection threshold is exceeded, the relay initiates start, trip and signaling functions according to its settings. It supports both definite-time and inverse definite minimum-time (IDMT) characteristics, while the built-in event and fault recording functions provide useful information for commissioning, fault analysis and maintenance.
For electrical automation and substation protection systems, SPAJ140C provides a compact solution for feeder protection, combining protection, indication, self-supervision and serial communication in one device. Its wide auxiliary-voltage options and configurable output contacts make it suitable for a variety of existing switchgear and protection-panel architectures.
Technical Specifications
| Parameter | Specification |
|---|---|
| Product Model | SPAJ140C |
| Manufacturer | ABB |
| Product Family | SPACOM |
| Product Type | Combined Overcurrent & Earth-Fault Relay |
| Overcurrent Protection | 3-phase, low-set and high-set |
| Earth-Fault Protection | Low-set and high-set, non-directional |
| Circuit Breaker Protection | Built-in breaker failure protection |
| Rated Current | 1 A or 5 A |
| Rated Frequency | 50 Hz or 60 Hz |
| Auxiliary Supply | 18–80 V DC / 80–265 V AC/DC |
| Low-Set Overcurrent | Definite-time / IDMT |
| High-Set Overcurrent | Instantaneous / definite-time |
| Earth-Fault Characteristic | Definite-time / IDMT |
| Communication | Serial interface |
| Input Type | Current-transformer secondary inputs |
| Output Contacts | Tripping and signaling relays |
| Self-Supervision | Built-in automatic diagnostics |
| Enclosure Protection | IP54 |
| Installation | Protection / switchgear panel |
| Typical Application | Feeder and network protection |
ABB documentation specifies 1 A or 5 A rated current inputs and 50/60 Hz operation. The auxiliary supply can be selected from 18–80 V DC or 80–265 V AC/DC depending on the relay configuration.
Main Features and Advantages
Integrated Overcurrent and Earth-Fault Protection
The ABB SPAJ140C combines two major feeder-protection functions in one relay. Its three-phase overcurrent unit continuously evaluates phase currents, while the earth-fault unit monitors residual current. This reduces the need for separate protection relays and simplifies protection-panel design.
Multi-Stage Protection
The relay provides low-set and high-set overcurrent stages as well as low-set and high-set earth-fault stages. The low-set functions can use definite-time or inverse-time characteristics, while the high-set functions provide rapid fault response. This flexibility allows engineers to coordinate the relay with upstream and downstream protection devices.
SPAJ140C
IDMT Protection Curves
SPAJ140C supports four standard inverse definite minimum time characteristics conforming to IEC and BS practices, together with specific RI and RXIDG characteristics. This allows protection engineers to achieve selective coordination across distribution networks.
Circuit-Breaker Failure Protection
A built-in circuit-breaker failure protection function provides an additional layer of protection when a breaker does not successfully clear a fault after a trip command. This is particularly important in medium-voltage substations where breaker failure can allow fault energy to persist.
Fault Recording and Diagnostics
The relay records measured and fault-related parameters, allowing maintenance personnel to review operating conditions associated with a protection event. A built-in self-supervision system provides automatic diagnostics and improves system availability.
Configurable Outputs
The SPAJ140C provides heavy-duty tripping contacts and additional signaling contacts. The output relays can be configured according to the application, allowing the same protection platform to support different alarm, trip and indication schemes.
Remote Communication
A serial communication interface enables the relay to exchange protection, event and diagnostic information with local or remote monitoring and control systems. This makes the SPAJ140C suitable for substation automation architectures in addition to conventional standalone protection panels.
Robust Industrial Construction
The relay uses an IP54-rated aluminium enclosure and is designed for electrically demanding substation environments. ABB documentation also highlights its immunity to electrical and electromagnetic interference and suitability for offshore applications.
Application Fields
ABB SPAJ140C is primarily designed for protection of medium-voltage distribution feeders and electrical networks where short-circuit and earth-fault protection must operate selectively and reliably.
In power generation and substations, the relay can protect outgoing feeders, distribution transformers and associated medium-voltage circuits. Its multi-stage overcurrent functions allow engineers to coordinate protection settings with upstream breakers and downstream feeder relays.
In oil and gas facilities, SPAJ140C can be installed in medium-voltage switchgear supplying pumps, compressors, motors and process equipment. Earth-fault protection is particularly important in industrial networks where insulation degradation can develop into serious electrical faults.
In chemical and petrochemical plants, the relay can provide feeder protection for switchgear serving process units, utility systems and large rotating machinery. Its circuit-breaker failure function provides additional protection where reliable fault clearance is essential.
The ABB SPAJ140C is also applicable to metallurgy, pulp and paper, mining, marine/offshore installations and general industrial power distribution. Its combination of overcurrent, earth-fault, breaker-failure, fault-recording and communication functions makes it well suited to legacy substation automation systems where a multifunction protection relay is required.
When replacing an existing SPAJ140C, engineers should verify the rated CT current (1 A or 5 A), 50/60 Hz frequency, auxiliary supply version and exact order code. ABB’s ordering information shows different suffixes for auxiliary-voltage and frequency combinations, so the basic SPAJ140C designation alone is not sufficient to determine every electrical configuration.
Related Products
- SPAJ 141 C — Related SPACOM relay with a more sensitive earth-fault input circuit; suited to applications requiring higher earth-fault sensitivity.
- SPAJ 142 C — More sensitive earth-fault version of the SPAJ 140 C family.
- SPAJ 144 C — Later SPAJ 140 C family member offering enhanced protection functionality and additional protection stages.
- SPCJ 4D29 — Protection relay module used as the combined overcurrent/earth-fault relay element within the SPAJ 140 C assembly.
- SPTU 240 R1 — Power supply and output relay module for 80–265 V AC/DC configurations.
- SPTU 48 R1 — Power supply and output relay module for 18–80 V DC applications.
