Description
Detailed parameter table
| Parameter name | Parameter value |
| Product model | 07KR51 220VDC |
| Manufacturer | ABB |
| Product category | Overcurrent relay (protection relay series) |
| Protection type | Instantaneous and time-delayed overcurrent protection |
| Rated voltage | 220 VDC |
| Current input | 5 A AC (primary current up to 2000 A with CT) |
| Number of phases | 3-phase |
| Time delay range | 0.05 s to 10 s (adjustable) |
| Instantaneous setting range | 2 to 10 times rated current |
| Output contacts | 2 x SPDT (NO/NC) |
| Power consumption | Max 5 W |
| Operating temperature | -5°C to 55°C |
| Protection rating | IP40 |
| Dimensions | 144mm × 144mm × 120mm |
| Weight | 0.8kg |
| Certifications | IEC 60255, UL, CE |
| Mounting type | Panel mount (flush or surface) |
ABB 07KR51 220VDC
Product introduction
The ABB 07KR51 220VDC is a reliable overcurrent protection relay designed for safeguarding electrical distribution systems, motors, and transformers in industrial and utility applications. As part of ABB’s legacy protection relay series, this device combines precise current monitoring with adjustable time-delay and instantaneous tripping functions, making it suitable for both primary and backup protection roles.
Operating on a 220 VDC power supply, the ABB 07KR51 220VDC continuously measures three-phase currents, detecting overcurrent conditions that could indicate faults such as short circuits or overloads. Its dual output contacts provide flexible control options, allowing it to trigger circuit breakers, alarms, or other protective devices when abnormal conditions are detected.
In electrical networks, the ABB 07KR51 220VDC serves as a critical safety component, preventing equipment damage and minimizing downtime by isolating faulty sections before damage occurs. Its robust design and straightforward operation make it a trusted choice for retrofits in existing systems or new installations where reliable, cost-effective protection is required.
Core advantages and technical highlights
Dual protection modes: The ABB 07KR51 220VDC offers both time-delayed and instantaneous overcurrent protection, allowing customization for specific application needs. The time-delay function (0.05 s to 10 s) prevents nuisance tripping during transient overloads, while the instantaneous setting (2 to 10 times rated current) provides rapid response to severe faults. This versatility makes it suitable for protecting motors—where time delays accommodate start-up currents—and distribution lines, where fast fault clearance is critical.
Precise current measurement: Equipped with high-accuracy current sensing, the ABB 07KR51 220VDC maintains consistent performance across a wide range of input currents (up to 2000 A with current transformers). Its measurement accuracy of ±5% ensures reliable operation even in noisy electrical environments, reducing the risk of false trips or missed faults. This precision is particularly valuable in industrial settings with variable load conditions.
Flexible mounting and integration: The ABB 07KR51 220VDC features a compact 144mm × 144mm footprint and supports both flush and surface panel mounting, making it easy to install in control cabinets with limited space. Its SPDT output contacts (NO/NC) can directly interface with circuit breaker trip coils, alarm systems, or PLC inputs, eliminating the need for additional interface modules. This simplicity reduces installation time and system complexity.
DC power reliability: Designed to operate on 220 VDC, the ABB 07KR51 220VDC is ideal for applications where AC power may be unreliable or unavailable, such as remote substations or industrial plants with dedicated DC battery systems. The DC power supply ensures the relay remains operational during AC mains failures, providing continuous protection when it is most needed.
Typical application scenarios
In industrial facilities, the ABB 07KR51 220VDC protects medium-voltage motors used in pumps, compressors, and conveyors. Its adjustable time delay accommodates the high inrush currents during motor start-up (typically 6-8 times rated current), while the instantaneous setting trips quickly during stall conditions or phase-to-phase faults, preventing motor winding damage.
Within electrical distribution substations, the ABB 07KR51 220VDC serves as backup protection for feeder circuits. It works alongside primary protection devices to detect overcurrents that may go undetected, providing an additional layer of safety. Its 220 VDC operation ensures it remains functional during AC power outages, critical for maintaining protection in emergency situations.
In renewable energy systems, such as small hydroelectric plants, the ABB 07KR51 220VDC protects generators and step-up transformers. It monitors output currents, tripping the generator breaker during overloads or short circuits to prevent damage. The relay’s compatibility with DC battery systems makes it suitable for remote installations where reliable power is essential.
ABB 07KR51 220VDC
Related model recommendations
ABB 07KR52 220VAC: An AC-powered variant of the ABB 07KR51 220VDC, suitable for applications with stable AC power supplies.
ABB 07KT82: A thermal overload relay that pairs with the ABB 07KR51 220VDC to provide comprehensive motor protection, combining overcurrent and thermal monitoring.
ABB SACE Tmax XT: A circuit breaker series compatible with the ABB 07KR51 220VDC, where the relay’s output contacts trigger breaker tripping.
ABB CT-CLASS 0.5: Current transformers that provide accurate current signals to the ABB 07KR51 220VDC in high-current applications.
ABB CM-MPS: A DC power supply module that ensures stable 220 VDC input to the ABB 07KR51 220VDC in battery-backed systems.
ABB 07TR21: A earth fault relay that complements the ABB 07KR51 220VDC by detecting ground faults in ungrounded or high-resistance grounded systems.
Installation, commissioning and maintenance instructions
Installation preparation: Before installing the ABB 07KR51 220VDC, ensure the mounting panel is clean, dry, and securely fastened. Verify the 220 VDC power supply is properly fused (1A recommended) and isolated from AC circuits to prevent interference. Required tools include a screwdriver set, wire strippers, and a multimeter. Use 1.5 mm² copper wires for power and signal connections, ensuring current transformer secondary circuits are grounded at one point to avoid noise.
Maintenance suggestions: Inspect the ABB 07KR51 220VDC semi-annually for loose connections, dust, or signs of overheating. Clean the front panel with a dry cloth and check terminal screws for tightness. Test operation annually by injecting test currents (using a relay test set) to verify time-delay and instantaneous tripping functions match settings. Calibrate every 5 years to maintain accuracy, or immediately if the relay has been subjected to severe electrical transients. Keep a record of test results and settings to simplify troubleshooting.
Service and guarantee commitment
The ABB 07KR51 220VDC is backed by a 2-year warranty from the date of purchase, covering manufacturing defects and ensuring compliance with published specifications. ABB guarantees that any faulty unit will be repaired or replaced promptly, minimizing downtime in critical protection systems.
Technical support includes access to ABB’s documentation library, featuring installation guides, setting calculators, and application notes specific to the ABB 07KR51 220VDC. Customers can also consult ABB’s protection engineering team for assistance with setting calculations or system integration. For extended reliability, optional service contracts offer periodic testing, calibration, and technical training, ensuring the relay maintains optimal performance throughout its 15-year design lifespan.
