The ABB SPAJ 110 C-AA (RS 421 010-AA) is a multi-function numerical protection relay designed for selective short-circuit and earth-fault protection in radial distribution networks, specifically for feeders and power transformers.
Product Parameters (Datasheet)
- Model Number: SPAJ 110 C-AA
- Product ID: RS 421 010-AA
- Protection Functions: 3-phase overcurrent (low-set and high-set) and non-directional earth-fault (low-set and high-set)
- Auxiliary Voltage (Uaux): 80–265 V AC/DC (standard for “AA” variant)
- Rated Current (In): 1 A or 5 A (Field selectable)
- Rated Frequency (fn): 50 Hz or 60 Hz
- Low-set Stage (I>): 0.5–2.5 x In (Overcurrent) / 0.05–0.40 x In (Earth-fault)
- High-set Stage (I>>): 0.5–40 x In / 0.1–10 x In
- Time Characteristics: Definite time (DT) or Inverse Definite Minimum Time (IDMT)
- Communication: SPA-bus protocol via plastic fiber optic (standard)
- Protection Class: IP54 (Front), IP20 (Rear terminals)
Country of Origin
This protection relay was engineered and manufactured in Finland by ABB Relays (formerly Strömberg), a global leader in power system protection.
Application Fields
The SPAJ 110 C-AA is a versatile unit utilized in:
- Utility Substations: Primary protection for radial feeders in distribution grids.
- Industrial Power Systems: Protecting large transformers and motor supply lines.
- Marine & Offshore: Providing reliable fault detection in isolated shipboard power networks.
- Renewable Energy: Monitoring earth-fault conditions in solar or wind farm collection systems.
Product Usage Instructions
- Mounting: Install the relay in a standard A1-sized panel cutout. Ensure the case is properly earthed via the dedicated grounding screw.
- CT Connection: Connect the phase current transformers and the residual (neutral) current transformer to the rear terminals. Safety Warning: Ensure CTs are short-circuited before disconnecting the relay terminals.
- Settings (Potentiometers): Use the front-panel potentiometers and DIP switches to set the pick-up levels and time delays for both low-set and high-set stages.
- Testing: Use the “Test” button on the front panel to simulate a trip condition and verify the operation of the output relays and the visual indicators (LEDs).
- Resetting: After a trip, a red LED will stay lit to indicate the fault type. Press the “Reset” button to clear the targets once the fault has been cleared.
Product Technical Description
The SPAJ 110 C-AA belongs to the SPACOM product family. Technically, it is a micro-processor based unit that continuously monitors the phase and neutral currents. It uses digital filtering to extract the fundamental frequency components, ensuring that the relay does not mal-operate due to harmonics or transients. The “C-AA” designation identifies the specific hardware version and auxiliary power range, ensuring compatibility with most DC battery systems found in substations. Its modular design allows the internal plug-in unit to be removed from the case without disturbing the fixed wiring.
Q&A (Common Questions)
Q: Can I change the IDMT curves on this relay? A: Yes, the relay supports standard IEC 60255 curves, including Normal Inverse, Very Inverse, Extremely Inverse, and Long-time Inverse, selectable via internal DIP switches.
Q: Does the “AA” suffix affect the current rating? A: No, the “AA” primarily refers to the auxiliary supply voltage range and the communication interface type. The current rating (1A/5A) is determined by the internal CT wiring terminals used.
Q: Is this relay compatible with SCADA? A: Yes, via the rear fiber-optic interface and a suitable bus connection (SPA-ZC), the relay can transmit measurements, events, and settings to a remote SCADA system.
Q: What happens if the auxiliary power is lost? A: As a numerical relay, it requires auxiliary power to function. If power is lost, the protection will not operate. For critical paths, a reliable DC battery source is recommended.
Similar Model Recommendations
- ABB SPAJ 140 C (Advanced overcurrent and earth-fault relay)
- ABB SPAM 150 C (Motor protection relay)
- ABB SPAJ 115 C (Alternative earth-fault specific variant)
- ABB REF 541 (Modern feeder protection successor)
- ABB REJ 521 (Compact feeder protection module)
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