Description
Key Technical Specifications
- Model Number: ABB 07KR51 1SBP260011R1001
- Manufacturer: ABB Power Grids Division
- Protection Functions: High-impedance differential (stator faults), overcurrent backup, phase unbalance protection
- Fault Detection Range: 0.5A to 800A (phase-to-phase, phase-to-ground stator faults)
- Accuracy Class: 0.5S (current measurement), 1.0 (differential protection)
- CPU Architecture: 64-bit ARM Cortex-A9, 1GHz clock speed
- Communication Ports: 2 × 10/100/1000Mbps Ethernet (IEC 61850 GOOSE/MMS), 1 × RS485 (Modbus RTU)
- Power Supply: 110/220V AC/DC ±15% (switch-selectable), 20W max power consumption
- Operating Temperature: -25°C to +70°C (-13°F to +158°F)
- Isolation Rating: 2kV AC (current inputs to control circuit); 1kV AC (communication ports)
- Certifications: IEC 61508 (SIL 3), IEC 60255, CE, UL 508, RoHS 2.0
- CT Ratio Compatibility: 100:5 to 2000:5 (software-configurable, no external transformers)
- Inputs/Outputs: 8 × analog current inputs (CT secondary), 16 × digital inputs, 8 × configurable digital outputs (NO/NC)
ABB 07KR51 1SBP260011R1001
Field Application & Problem Solved
In power generation—coal/gas-fired plants, industrial cogeneration, and petrochemical generator sets—stator winding faults are the most costly and dangerous generator failures. A Midwest coal plant lost $2.3M when a generic differential relay failed to detect a phase-to-ground fault, burning out 30% of the generator stator and requiring a 3-week repair. Legacy relays also lack modern communication integration: a Texas petrochemical plant spent $45k on protocol gateways to connect old relays to their IEC 61850 SCADA system, leading to 3 hours of monthly downtime from communication lags and misconfigured data.
You’ll find this relay in generator control panels across critical power systems: 50MW+ coal plant generators in Pennsylvania, 10MW cogeneration units in Louisiana petrochemical facilities, and backup generators in Florida data centers. Its core value is fast, selective fault detection + native modern communication. The high-impedance design eliminates nuisance trips from inrush currents (common with low-impedance relays) while detecting actual faults in <20ms—cutting the Midwest plant’s stator damage risk by 95%, with zero catastrophic failures in 5 years. At the Texas plant, built-in IEC 61850 support replaced four external gateways, eliminating communication delays and saving $36k annually in maintenance and downtime.
For a European gas-fired power plant, SIL 3 certification ensured compliance with strict grid safety regulations, avoiding $280k in non-compliance fines. Its wide CT ratio compatibility also simplified a generator retrofit, replacing three specialized relays with one 07KR51 and reducing spare parts inventory costs by $18k.
Installation & Maintenance Pitfalls (Expert Tips)
- CT Wiring Polarity Is Non-Negotiable: Rookies reverse CT secondary wiring, creating false differential currents that trigger nuisance trips. A North Carolina cogeneration plant did this, leading to five unplanned generator shutdowns in a month. Follow ABB’s dot notation on CTs and relay terminals to ensure correct polarity—use a phase rotation tester to verify current flow direction before commissioning.
- Power Supply Selection: Set Before Power-Up: Applying 220V AC to a relay configured for 110V AC fries the internal power module. A Colorado mining plant ruined two relays ($12k) before checking the selector switch. Confirm the plant’s power supply (110/220V) and set the relay’s internal switch—label the setting clearly for future maintenance teams.
- GOOSE Message Mapping: Test Communication: Incorrect IEC 61850 GOOSE configuration delays trip signals to the DCS. A Pennsylvania power plant’s relay failed to send a trip status update, leading to a 2-minute delay in isolating a faulty generator. Use ABB’s PCM600 software to map GOOSE datasets (trip, alarm, status) to DCS tags, and validate with a GOOSE sniffer tool to confirm real-time data transfer.
- Annual Calibration: Don’t Skip It: Uncalibrated relays drift in differential settings, missing minor faults. A Michigan paper mill’s 07KR51 failed to detect a 0.8A differential current (early stator fault) because it hadn’t been calibrated in 3 years. Use ABB’s 1SVR730700R0000 test kit to calibrate annually, and verify differential pickup settings against the generator’s nameplate data (stator current rating, CT ratio).
ABB 07KR51 1SBP260011R1001
Technical Deep Dive & Overview
The ABB 07KR51 is a high-impedance differential protection relay engineered to safeguard generator stator windings from catastrophic faults. At its core, a 64-bit ARM Cortex-A9 processor processes real-time current signals from CTs (current transformers) connected to each generator phase. The high-impedance design uses a built-in stabilizing resistor to suppress transient currents (e.g., motor inrush, CT saturation), ensuring selective tripping only during actual faults—addressing a major flaw of low-impedance relays that often trip unnecessarily.
The relay continuously calculates the differential current (Id = |I1 – I2|) by comparing incoming phase currents. If Id exceeds the user-configurable pickup setting (0.5A to 800A), the relay triggers a trip signal in <20ms, isolating the generator via circuit breakers to minimize damage. A backup overcurrent function activates if the differential circuit fails, providing a redundant safety layer.
Native IEC 61850 communication eliminates the need for external gateways, enabling real-time data transfer (fault type, current magnitudes, event timestamps) to DCS/SCADA systems. The relay stores up to 100 fault records in non-volatile memory, including pre-fault and post-fault waveforms, simplifying root-cause analysis.
Ruggedization features include a conformal-coated PCB and wide operating temperature range (-25°C to +70°C), ideal for unconditioned generator enclosures. Unlike generic relays, it’s factory-calibrated for wide CT ratio compatibility (100:5 to 2000:5), eliminating the need for external matching transformers. Its SIL 3 certification ensures compliance with safety standards for critical power systems, making it a reliable backbone for generator protection in environments where downtime costs $20k+/minute.
