Description
Key Technical Specifications
- Model Number: RET620 5BTNAAAANDC1BNN21G
- Manufacturer: ABB Power Grids Division
- Protection Functions: Transformer differential (87T), overcurrent (50/51), earth fault (59N/64N), overvoltage (59)/undervoltage (27), thermal overload (49), circuit breaker failure (50BF), tap-changer protection
- Communication Protocols: IEC 61850 (GOOSE, Sampled Values), Modbus RTU/TCP, DNP3.0, IEC 60870-5-104
- Power Supply: 24VDC ±10% (19.2-26.4VDC); 18W typical power consumption
- Operating Temperature: -25°C to +70°C (-13°F to +158°F)
- Isolation Rating: 2kV AC (input to control/communication); 5kV AC (power circuits to ground)
- I/O Configuration: 12 digital inputs (DI), 8 digital outputs (DO); 6 analog inputs (AI) for CT/VT signals
- CT/VT Ratings: CT: 1A/5A (configurable); VT: 100V/220V (line-line)
- Display & HMI: 4.3” color LCD, tactile buttons, LED status indicators
- Certifications: CE, UL 10C, IEC 61850-3/5, IEC 60255-1, SIL 2/3 (IEC 61508), RoHS 2.0, ATEX Zone 2
- Compatibility: ABB MicroSCADA Pro, third-party SCADA systems, IEC 61850-compliant substation devices
- Memory & Logging: 20,000 event logs, 1,000 fault records (with waveform capture)
- Firmware Version: v7.0+ (compatible with latest IEC 61850 revisions)
ABB RET620 5BTNAAAANDC1BNN21G
ABB RET620 5BTNAAAANDC1BNN21G
Field Application & Problem Solved
In power utilities and industrial substations, transformer protection demands precision, reliability, and seamless integration with modern substation automation systems (SAS). Generic protective relays fail two critical tests: advanced transformer differential logic (to distinguish internal faults from inrush currents) and native IEC 61850 compliance. A Midwest utility lost $650k in a 7-hour outage when a generic relay misclassified a transformer winding fault as inrush current, leading to catastrophic damage. Legacy relays also require external gateways to connect to SAS, causing communication lags and increasing maintenance complexity—costing a Texas industrial plant $45k annually in gateway maintenance and downtime.
You’ll find this relay protecting: 11kV-220kV distribution/transmission transformers, industrial plant main transformers (5-100MVA), and solar/wind farm grid-tie transformers. It’s the standard for facilities prioritizing regulatory compliance (NERC CIP, IEC 61511) and minimal downtime. Its core value is ABB-native transformer protection logic + IEC 61850 integration + SIL 3 reliability. Unlike generics, it uses ABB’s proprietary differential protection algorithm to eliminate nuisance trips during transformer inrush, while native IEC 61850 GOOSE support enables sub-10ms inter-relay communication—critical for substation-wide fault coordination. For a California solar farm, the relay’s -25°C to +70°C operating range withstood desert heat and winter cold, avoiding $20k per substation in climate-controlled enclosure costs.
Installation & Maintenance Pitfalls (Expert Tips)
- CT Polarity: Match “Dot” Markings Exactly: Rookies reverse CT secondary wiring, causing differential protection misoperation. A Florida utility’s transformer relay tripped incorrectly during normal load until technicians aligned the CT “dot” markings with the relay’s polarity indicators. Use a polarity tester to verify—incorrect wiring voids protection integrity and can lead to unprotected faults.
- IEC 61850 GOOSE Dataset Synchronization: Mismatched GOOSE dataset names between relays and SAS cause communication failures. An Ohio industrial plant’s circuit breaker failure protection didn’t activate until GOOSE datasets were standardized in the SAS. Use ABB’s Relion Engineer software to align dataset names and test message latency (target <10ms).
- Firmware Mismatch with SAS: Outdated relay firmware (pre-v7.0) doesn’t support IEC 61850-9-2 Sampled Values, leading to incomplete fault data. A Pennsylvania utility’s fault records lacked waveform data until the RET620 was updated to v7.3. Always verify firmware compatibility with your SAS vendor—check ABB’s compatibility matrix before commissioning.
- Grounding: Connect to Substation Ground Grid: Sharing the relay’s ground with non-critical equipment introduces noise, causing false overcurrent trips. A Texas wind farm’s relays tripped weekly until connected to the substation’s dedicated ground grid (ground resistance <0.5Ω). Route ground wires separately from power cables and avoid daisy-chaining grounds.
- Test All Protection Functions Post-Installation: Rookies skip testing niche functions (e.g., tap-changer protection) during commissioning. A Midwest utility missed a faulty 49 (thermal overload) function, leading to a near-miss when a transformer overheated. Use ABB’s test kit (1SVR730700R0000) to simulate all fault types—document results for regulatory compliance.
Technical Deep Dive & Overview
The ABB RET620 5BTNAAAANDC1BNN21G is a utility-grade digital protective relay engineered to monitor and protect power transformers using advanced signal processing and protection logic. At its core, a 32-bit digital signal processor (DSP) samples CT/VT inputs at 1kHz, executing ABB’s proprietary differential protection algorithm—designed specifically to distinguish internal faults from transformer inrush currents (a common cause of nuisance trips with generic relays). The relay’s multifunctional design integrates 10+ protection functions, eliminating the need for multiple single-purpose relays in substation cabinets.
Unlike generic relays, it natively supports IEC 61850 (GOOSE for fast peer-to-peer communication, Sampled Values for digital CT/VT integration), enabling seamless integration with modern SAS. This eliminates latency from external protocol converters and simplifies engineering via standard IEC 61850 data models. The relay’s rugged design includes a conformal-coated PCB, wide operating temperature range, and 5kV AC isolation—critical for harsh substation environments with electrical noise, dust, and temperature extremes.
What sets it apart is its asset management capabilities: it logs 20,000 events and 1,000 fault waveforms, providing actionable data for predictive maintenance (e.g., detecting incipient transformer winding faults). Integration with ABB’s Relion Engineer software allows remote configuration, firmware updates, and fault analysis—reducing on-site maintenance time by 40%. For utilities and industrial plants where transformer downtime costs $100k+/hour, this relay isn’t just a protective device—it’s a critical component of a reliable, efficient power asset management system.
