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Voltage Protection Relay Woodward MRU3-11D

Voltage Protection Relay Woodward MRU3-11D

The Woodward MRU3-11D, also cataloged as the MRU3 Voltage Protection Relay, operates as a dedicated hardware component for direct voltage monitoring, overvoltage/undervoltage protection, and phase unbalance evaluation within AC distribution...

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Availability: Low stock: 10 left

SKU: MRU3-11D
Vendor: Woodward
Category: Voltage Protection Relay
Related Series:

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The Woodward MRU3-11D, also cataloged as the MRU3 Voltage Protection Relay, operates as a dedicated hardware component for direct voltage monitoring, overvoltage/undervoltage protection, and phase unbalance evaluation within AC distribution platforms.

Hardware Specifications

Parameter Specification
Model MRU3-11D
Brand Woodward
Origin USA
Weight 0.4 kg
Dimensions 108 mm x 70 mm x 115 mm
Operating Temp -20 to +60 deg C (-4 to +140 deg F)
Power Consumption 24 VDC / 85-265 VAC/DC supply input
Voltage Monitoring Range 0 to 690 VAC
Accuracy +/-1% of nominal voltage
Relay Outputs 1 SPDT relay (NO/NC), rated at 5 A, 250 VAC
Digital Outputs 2 independent outputs for alarm and trip functions
Analog Output 4-20 mA for voltage level indication
Communication Protocols Modbus RTU via RS485
Mounting DIN rail mount

Actuator Loop Feedback Response and Dynamic Protection Execution

The Woodward MRU3-11D monitors 0 to 690 VAC system lines with +/-1% accuracy to deliver deterministic actuator loop feedback response. Upon detecting out-of-spec voltage parameters or phase asymmetry, the internal micro-controller actuates its 5 A SPDT contact and dual digital outputs to execute breaker trips and alarm sequences. Simultaneously, the integrated 4-20 mA analog output transmits real-time voltage telemetry, while Modbus RTU over RS485 enables direct integration into master control networks.

Frequently Asked Questions

Q: What are the auxiliary power supply options for the Woodward MRU3-11D relay?

A: The module supports flexible power supply inputs, operating on either 24 VDC or 85 to 265 VAC/DC auxiliary sources.

Q: What output options are available for signal telemetry and control interlocks?

A: The relay provides one 5 A / 250 VAC SPDT relay contact, two independent digital outputs for trip/alarm signals, and one 4-20 mA analog output for continuous voltage indication.

Q: How is serial communication established with high-level control systems?

A: The module integrates an RS485 serial interface utilizing the Modbus RTU protocol for real-time data acquisition and setpoint configuration.

Field Installation Guidelines

  • Mount the 108 mm x 70 mm x 115 mm enclosure onto a standard 35 mm DIN rail in a clean cabinet environment.
  • Wire the 0 to 690 VAC voltage sensing inputs through dedicated isolation fuses, ensuring proper line-to-line phase pairing.
  • Use shielded twisted-pair cabling for the RS485 communication line and ground the cable shield at a single earth point to eliminate ground loops.
  • Separate low-voltage analog (4-20 mA) and digital signaling wiring from high-voltage AC power and SPDT relay contact connections.