Product Description

Overview

The RET615 is a dedicated transformer protection and control relay designed for two-winding power transformers, step-up transformers, and generator-transformer blocks in both utility and industrial power distribution systems. Part of ABB’s Relion® 615 series, it combines high-speed differential protection, integrated monitoring, and flexible communication interfaces in a compact, withdrawable unit.

Key Features

Advanced Transformer Protection

• High-speed three-phase differential protection with bias stabilization and instantaneous high-set stage for internal fault clearance.

• Harmonic blocking for 2nd and 5th harmonics to prevent nuisance trips during inrush or overexcitation.

• Sensitive restricted earth fault (REF) protection with support for high-impedance and low-impedance neutral grounding.

Integrated Control & Monitoring

• Tap changer management with built-in Automatic Voltage Regulator (AVR) for on-load tap changers (OLTC).

• Direct control of circuit breakers and disconnectors from HMI or remotely.

• Arc flash detection with fast response using optional optical sensors.

Digital Substation Communication

• Supports IEC 61850 Editions 1 and 2, including GOOSE messaging and Sampled Values (IEC 61850-9-2 LE).

• Network redundancy via HSR and PRP protocols for uninterrupted communication.

• Compatible with Modbus, DNP3, and IEC 60870-5-103 for flexible integration.

Maintenance-Friendly Design

• Withdrawable plug-in unit allows safe replacement without disconnecting field wiring; built-in CT shorting ensures safety.

• Large graphical display with customizable Single Line Diagram (SLD) accessible locally or via web browser.

• Compact footprint suitable for standard distribution transformers while providing extensive functionality.

Thermal & Condition Monitoring

• Thermal modeling of transformers for accurate overload protection and insulation longevity.

• Through-fault energy tracking for predictive maintenance and life-cycle optimization.

Technical Specifications

Applications

• Protection and control of utility and industrial power transformers.

• Integration into digital substations with IEC 61850-based communication.

• Ideal for two-winding transformers in distribution networks.

• Predictive maintenance through thermal and through-fault monitoring.

FAQ

Q: Is RET615 suitable for three-winding transformers?
A: RET615 is optimized for two-winding transformers. For three-winding transformers, consider RET620 or RET670.

Q: Can it handle on-load tap changer control?
A: Yes, it includes an integrated Automatic Voltage Regulator for OLTC management.

Q: Does RET615 support IEC 61850 communication?
A: Yes, including GOOSE messaging, Sampled Values, HSR, and PRP redundancy.

Q: Can the relay be withdrawn safely without powering down the system?
A: Yes, its plug-in design includes automatic CT shorting for safe maintenance.