ABB RET615E-1G Transformer Protection and Control Relay  

1. Core Functions & Protection Features

• Comprehensive Transformer Differential Protection:
  Equipped with percentage-biased differential protection and differential instantaneous protection, providing fast and reliable coverage for phase-to-phase faults, winding turn-to-turn faults, and bushing faults. The adaptive bias logic reduces false tripping caused by inrush currents during transformer energization.
• Sensitive Ground Fault Protection:
  Features restricted earth fault (REF) protection (for winding ground faults) and neutral overcurrent protection (for system ground faults), with adjustable pickup currents (0.1A~10A) to detect low-level ground faults that may bypass conventional overcurrent protection.
• Thermal Overload Protection:
  Uses a dynamic thermal model to simulate transformer winding temperature, accounting for load fluctuations, ambient temperature, and start-stop cycles. Triggers alarms or trips to prevent insulation damage from sustained overloading (compliant with IEC 60076 transformer thermal standards).
• Voltage & Frequency Protection:
  • Overvoltage protection (59): Trips if input/output voltage exceeds 105%~120% of rated voltage (adjustable) to prevent core saturation.
  • Undervoltage protection (27): Activates for voltage dips below 70%~90% of rated voltage (configurable) to avoid under-excitation damage.
  • Zero-sequence overvoltage protection (59N): Detects unbalanced system voltages (e.g., single-phase ground faults) in ungrounded or high-impedance grounded systems.
• Breaker Failure Protection (50BF/51BF):
  Monitors circuit breaker tripping status; if the breaker fails to interrupt a fault within a set time (0.1s~2s), it sends a trip signal to backup breakers, preventing fault escalation.
• Control & Monitoring Functions:
  • Local/remote control of transformer on/off, tap changer adjustment (for load tap changers, LTC), and cooling fan/pump activation.
  • Real-time measurement of key parameters: 3-phase current/voltage, active/reactive power, energy (kWh/kVARh), power factor, and transformer winding temperature (via RTD input).

2. Technical Parameters

• Electrical Inputs:
  • Current Inputs: 6× CT inputs (5A or 1A secondary, configurable) for differential and overcurrent protection.
  • Voltage Inputs: 6× PT inputs (100V phase-phase / 57.7V phase-neutral, 50/60Hz) for voltage monitoring and differential voltage protection.
  • RTD Inputs: 4× PT100/PT1000 inputs (for winding and oil temperature measurement, accuracy ±0.5℃).
• Communication Interfaces:
  • 2× Ethernet ports (IEC 61850 GOOSE/MMS, Modbus-TCP) for integration into digital substations or SCADA systems.
  • 1× RS-485 port (Modbus RTU) for communication with local devices (e.g., tap changers, cooling systems).
  • Optional: IEC 60870-5-103 or DNP3.0 for compatibility with legacy automation systems.
• Power Supply:
  • DC: 24V/48V/110V/220V (±20% tolerance).
  • AC: 110V/220V (±15% tolerance, 50/60Hz).
  • Typical power consumption: ≤15W.
• Environmental Ratings:
  • Operating Temperature Range: -25℃~+70℃ (-13℉~158℉).
  • Storage Temperature Range: -40℃~+85℃ (-40℉~185℉).
  • Protection Class: IP54 (front panel); IP20 (when installed in a cabinet).
• Compliance Standards:
  IEC 62271-202 (MV switchgear), IEC 60255 (relay standards), IEC 61850 (digital substation communication), UL 508 (electrical safety).

3. Key Product Advantages

• Adaptive Inrush Current Mitigation: The differential protection’s adaptive bias algorithm distinguishes between transformer inrush currents and actual faults, eliminating false tripping during energization—critical for frequent transformer startups (e.g., in industrial plants).
• Digital Substation Readiness: Full IEC 61850 compliance (GOOSE for fast peer-to-peer control, MMS for data exchange) enables seamless integration into smart substations, supporting remote configuration and condition monitoring.
• Flexible Control Logic: Configurable via ABB PCM600 software to support custom control schemes (e.g., automatic tap changer adjustment based on load voltage, cooling system activation based on temperature)—adapting to diverse transformer types (e.g., two-winding, three-winding).
• Advanced Diagnostics & Event Logging: Logs up to 1000 fault events, 100 waveform captures, and real-time temperature/power trends. This data facilitates predictive maintenance (e.g., identifying abnormal load cycles) and root-cause analysis of faults.
• Rugged Industrial Design: Wide temperature tolerance, IP54 front-panel protection, and anti-vibration performance (IEC 60068-2-6: 50Hz, 5g acceleration) ensure reliability in harsh substation environments (dust, humidity, voltage transients).

4. Application Fields

• Utility Substations: Protects power transformers (e.g., 110kV/35kV, 220kV/110kV) in transmission and distribution networks, ensuring stable power supply to residential, commercial, and industrial areas.
• Industrial Power Systems: Safeguards unit transformers (connecting generators to the grid) and process transformers in steel mills, cement plants, and chemical facilities—preventing production downtime from transformer faults.
• Renewable Energy Plants: Protects step-up transformers in solar farms and wind parks (e.g., 35kV/110kV), connecting renewable energy sources to the grid while ensuring compliance with grid codes (e.g., low-voltage ride-through).
• Data Centers & Critical Infrastructure: Secures transformers in backup power systems (e.g., UPS-linked transformers) for hospitals, data centers, and airports—ensuring uninterrupted power for life-critical or mission-critical loads.
• Mining & Heavy Industry: Protects large transformers in mining operations (powering crushers, conveyors) and marine applications (shipboard transformers), withstanding harsh conditions like vibration, dust, and salt spray.

5. Precautions

• CT/PT Compatibility: Ensure current transformers (CTs) and voltage transformers (PTs) match the relay’s secondary input ratings (5A/1A for CTs, 100V/57.7V for PTs). Mismatched transformers will cause measurement errors or protection failure.
• Differential Protection Calibration: Use PCM600 to input transformer parameters (winding ratio, tap changer range, CT ratio) for differential protection calibration. Incorrect settings may lead to under-protection (faults not detected) or over-protection (false tripping).
• Communication Protocol Alignment: When integrating with SCADA/DCS systems, confirm compatibility between the relay’s protocols (IEC 61850, Modbus) and the upper-level system. Update firmware via PCM600 if needed to resolve protocol mismatches.
• Power Supply Reliability: Connect to a dedicated, regulated power supply with surge protection. Voltage fluctuations or outages may disable protection functions, risking transformer damage during faults.
• Environmental Protection: Install the relay in a dust-proof, moisture-proof cabinet in harsh environments. Avoid direct exposure to corrosive gases (e.g., sulfur, chlorine) or extreme temperatures beyond the specified range.
• Regular Maintenance: Periodically verify protection settings, test tripping logic via PCM600, and inspect RTD connections (for temperature monitoring). Replace the relay if it fails self-diagnostics or shows signs of physical damage (e.g., burnt terminals)