The SPAJ 140 C is a high-performance, multi-function combined overcurrent and earth-fault relay developed by ABB, designed for feeder protection in power systems. This relay integrates three-phase overcurrent protection, earth-fault protection, and circuit breaker failure protection into a single unit. It features flexible configuration and powerful communication capabilities, making it widely applicable in medium and low-voltage distribution systems, industrial power networks, and substations to provide reliable selective short-circuit and earth-fault protection for electrical equipment.
The SPAJ 140 C employs a modular design, offering excellent scalability and maintainability. Its core protection module is the SPCJ 4D29, which works in conjunction with the power supply and output relay module (SPTU 240 R1 or SPTU 48 R1), the input module (SPTE 4E1), and the bus connection module (SPA-ZC series) to adapt to various application scenarios and power supply conditions. The relay supports on-site configuration and remote parameter setting and is equipped with self-supervision and fault diagnosis functions, significantly enhancing system reliability and availability.
This product is suitable for solidly earthed, resistance earthed, or impedance earthed power systems. It can be used for selective protection of radial feeders and in other applications requiring single-phase, two-phase, or three-phase overcurrent protection and non-directional earth-fault protection.
II. Key Features
Three-phase low-set overcurrent protection unit with definite time or Inverse Definite Minimum Time (IDMT) characteristic.
Three-phase high-set overcurrent protection unit with instantaneous or definite time function.
Low-set non-directional earth-fault protection unit with definite time or IDMT characteristic.
High-set non-directional earth-fault protection unit with instantaneous or definite time function.
Built-in Circuit Breaker Failure Protection (CBFP) function.
Two heavy-duty and four light-duty output relays, support field-configuration.
Equipped with a serial communication interface, supporting fiber-optic SPA bus communication.
High design flexibility to adapt protection schemes for different application scenarios.
Digital display of setting values, measured values, fault records, and other information.
Hardware and software self-supervision with auto-diagnosis capability.
Supports parameter setting and recording via a portable PC.
III. Functional Description
The SPAJ 140 C relay, connected to the current transformers of the protected object, continuously monitors three-phase currents and the neutral current. Upon fault detection, the relay initiates the corresponding protection stage, issues a trip signal, can initiate auto-reclosing, records fault data, etc.
Overcurrent Protection Unit:
Low-set stage (I>): Start current range: 0.5 to 5.0 × In (definite time) or 0.5 to 2.5 × In (IDMT). Operate time range: 0.05 to 300 s.
High-set stage (I>>): Start current range: 0.5 to 40.0 × In. Operate time range: 0.04 to 300 s.
Earth-Fault Protection Unit:
IDMT Characteristic Curves:
Supports six time-current curves, including:
Standard curves: Normal Inverse, Very Inverse, Extremely Inverse, Long-Time Inverse (compliant with BS 142 and IEC 60255 standards).
Special curves: RI-type curve, RXIDG-type curve (ABB standards).
Circuit Breaker Failure Protection (CBFP):
If the fault is not cleared within a set time (0.1 to 1.0 s) after the trip signal is issued, a backup trip is initiated.
Communication Function:
Supports communication with station control devices (e.g., SRIO 1000M) via the fiber-optic SPA bus, enabling telemetry, remote control, remote signaling, and fault recording.
IV. Product Structure and Operation
The SPAJ 140 C is designed for flush mounting. The housing is made of aluminum with a beige finish. The front panel is equipped with:
Digital display (1 red + 3 green digits)
Measured current indicators (IL1, IL2, IL3, I0)
Setting value indicators (I>, t>, I>>, t>>, I0>, t0>, I0>>, t0>>)
Switchgroup indicators (SGF, SGB, SGR)
Control push buttons (RESET/STEP, PROGRAM)
Trip indicator (TRIP)
Self-supervision alarm indicator (IRF)
Operation Modes:
Users can perform parameter setting, menu navigation, fault reset, etc., via the front panel buttons. It supports "Setting Mode" and "Test Mode," allowing manual or remote modification of protection parameters and activation of output signals via the serial port.
Event Recording Function:
The relay can record data from the last 5 fault events, including current values, start duration, number of operations, etc. Data can be read via the display or the communication interface.
V. Application Areas
The SPAJ 140 C is suitable for the following applications:
Feeder protection in medium and low-voltage distribution systems.
Overcurrent and earth-fault protection in industrial power systems.
Incoming/outgoing line and busbar protection in substations.
Backup protection for electrical equipment like generators and transformers.
Complex grid structures requiring high selectivity protection.
VI. Maintenance
Under environmental conditions specified in the technical data, the relay is practically maintenance-free. If operating conditions are harsh (e.g., high temperature, humidity, chemical corrosion), periodic visual inspection and dust removal are recommended. If the relay malfunctions or measured values deviate from specifications, it should be serviced by qualified personnel or the manufacturer.
Important Notes:
The relay contains ESD-sensitive components. Proper anti-static precautions must be taken before handling modules.
Exercise caution when modifying parameters to avoid maloperation or failure to operate.
Pay attention to cleanliness and alignment of fiber-optic interfaces when installing communication modules.
