Product Overview

The RET521 (Part Number 1MRK001530-AE) is a high-performance, multi-functional terminal within ABB’s prestigious Relion® series, specifically engineered for the comprehensive protection and management of power transformers. Designed for both utility substations and heavy industrial power networks, the RET521 serves as a centralized safeguard, integrating high-speed differential protection with advanced voltage regulation. This terminal is built to handle the complexities of multi-winding transformers, providing the deterministic logic required to manage on-load tap changers (OLTC) while maintaining absolute system stability. Its rugged construction ensures reliable performance in "Challenging Conditions," effectively shielding critical infrastructure from electrical faults and operational irregularities.

Technical Specifications

• Model Designation: RET521

• ABB Global ID: 1MRK001530-AE

• Product Series: Relion® Protection and Control

• Primary Protection Functions:

• High-speed Transformer Differential Protection

• Multi-stage Overcurrent and Earth Fault Protection

• Precision Voltage and Frequency Supervision

• Integrated Control Logic: Automatic Voltage Regulation (AVR) for On-Load Tap Changers

• Safety Features: Built-in Trip Circuit Supervision (TCS)

• Thermal Operating Range: -25°C to +55°C (-13°F to 131°F)

• Humidity Tolerance: 5% to 95% RH (Non-condensing)

• Compliance Standards: IEC Certified (Electromagnetic Compatibility & Safety)

• Physical Dimensions: 329 mm x 260 mm x 270 mm

• Net Weight: 5.0 kg (11.0 lbs)

Total Transformer Asset Protection

The RET521 is a "Complete Defense" system for high-value power assets. By combining differential protection with earth fault and overcurrent monitoring, the terminal provides 360-degree coverage against internal winding faults and external system surges. The integrated voltage regulation feature is a critical efficiency driver; it automatically manages the tap changer positions to maintain a stable output voltage under varying load conditions, significantly reducing mechanical wear on the transformer and improving downstream power quality. Its heavy-duty 5 kg chassis is built to minimize mechanical resonance and provide superior shielding against the high electromagnetic fields common in substation environments.