Woodward HighPROTEC MRU4 A0AA Voltage Protection Relay

The Woodward MRU4 A0AA is a digital voltage protection relay within the HighPROTEC series. Equipped with dual-core processing architecture, it monitors grid voltage and frequency fluctuations to protect generators, transformers and distribution equipment against overvoltage, undervoltage and unbalanced voltage faults.

This A0AA variant adopts door flush mounting design without built-in communication interface. It integrates multiple ANSI protection functions, supports local parameter setting and fault recording. Its compact structure fits medium voltage switchgear cabinets for power grid and industrial energy system protection and spare part replacement.

Main Specifications

• Brand: Woodward (HighPROTEC)
• Model: MRU4 A0AA
• Device Type: Digital Voltage & Frequency Protection Relay
• Mounting: Flush door mounting (A housing type)
• Communication: No built-in communication interface
• Measurement Range: 0 ~ 800 VAC voltage input
• Protection Functions: ANSI 27, 59, 59N, 47, 81U/O, ROCOF
• Digital I/O: 8 digital inputs, 6 relay binary outputs
• Operating Temperature: -20°C ~ +60°C
• Configuration Software: Smart View

Core Functions

• Continuous monitoring of three-phase voltage and system frequency
• Overvoltage, undervoltage, residual voltage and voltage asymmetry protection
• Underfrequency, overfrequency and ROCOF rate-of-change frequency protection
• Voltage transformer supervision (60FL) and trip circuit monitoring (74TC)
• Programmable logic functions and customizable alarm & trip thresholds
• Built-in fault recorder, event log and disturbance waveform recording
• Local human-machine interface for parameter adjustment and status check
• Multiple relay output contacts for alarm signals and breaker tripping
• Integrated fault simulator for convenient commissioning and testing
• Self-diagnosis to detect internal hardware abnormalities automatically

Application Scenarios

• Medium voltage distribution cabinet voltage protection systems
• Cogeneration generator grid connection interface protection
• Wind power and photovoltaic station grid monitoring relays
• Industrial plant internal power distribution network protection
• Water treatment and mining power supply control cabinets
• Petrochemical plant auxiliary power system monitoring equipment
• SF6 compact switchgear built-in protection devices
• Microgrid voltage stability monitoring and protection control
• Woodward HighPROTEC protection system renovation and spare parts
• Commercial building medium voltage power distribution automation projects