ABB REX 521 | Feeder Protection Relay | Relion Series

Product Description

The ABB REX 521 feeder protection relay is part of the Relion series, designed to provide comprehensive protection and control for distribution feeders. It integrates advanced measurement, monitoring, and protection functions, ensuring reliable operation in utility and industrial networks.

Key Features

• Feeder protection functions including overcurrent, earth-fault, and breaker failure protection

• Flexible current inputs supporting rated values of 0.2 A, 1 A, or 5 A

• High withstand capability for continuous and short-term overloads

• Auxiliary power supply options for both AC and DC systems

• Compact design suitable for switchgear and control panel integration

• Event recording and diagnostics for fault analysis and system reliability

Technical Specifications

• Manufacturer ABB

• Model REX 521

• Series Relion

• Product Type Feeder Protection Relay

• Rated Frequency 50/60 Hz

• Current Inputs 0.2 A / 1 A / 5 A

• Thermal Withstand (Continuous) 1.5 A / 4 A / 20 A

• Thermal Withstand (1 second) 20 A / 100 A / 500 A

• Dynamic Current Withstand (half-wave) 50 A / 250 A / 1250 A

• Input Impedance <750 mΩ / <100 mΩ / <20 mΩ

• Voltage Inputs (Rated) 100 V (parametrizable)

• Voltage Withstand (Continuous) 240 V (2 × Un)

• Burden at Rated Voltage <0.5 VA

• Sensor Input Voltage Range (RMS) 9.4 V

• Sensor Input Voltage Range (Peak) ±12 V

• Sensor Input Impedance >4.7 MΩ

• Sensor Input Capacitance <1 nF

• Auxiliary Power Supply Types PS_87H and PS_87L

• Auxiliary AC Voltage 110/120/220/240 V (PS_87H)

• Auxiliary DC Voltage 110/125/220 V (PS_87H), 24/48/60 V (PS_87L)

• Voltage Variation AC: 85–110% rated, DC: 80–120% rated

• Burden <20 W

• Ripple in DC Supply Max. 12% (IEC 60255-11)

• Interruption Time (DC Supply) <40 ms (110 V), <100 ms (200 V), <15 ms (24 V), <50 ms (48 V)

• Internal Overtemperature Indication +78 °C (range +75…83 °C)

Application Scenarios

• Utility distribution feeders requiring dependable protection

• Industrial power systems with multiple feeder arrangements

• Switchgear panels where compact and configurable relays are essential

FAQ

Q: What auxiliary power supply options are available for the REX521?  A: It supports both AC and DC auxiliary supplies, with PS_87H for higher voltage ranges and PS_87L for lower DC voltages.

Q: Can the REX521 handle short-term overloads?  A: Yes, it withstands up to 500 A for 1 second depending on the rated current input.

Q: Is the REX521 suitable for sensor inputs?  A: Yes, it supports sensor input voltage ranges up to ±12 V peak with high input impedance.

Similar Model Comparison

• REX521: Feeder protection relay, flexible current inputs, AC/DC auxiliary supply options

• REF615: Compact feeder protection relay with IEC 61850 communication support

• REC650: Bay control IED with extended HMI and 132 kV rating