Configured for current monitoring and overcurrent protection in electrical power systems, the Woodward MRD1G5MA (MRD1G5MA Digital Protection Relay) provides direct physical/electrical execution.

Suffix Breakdown & Model Matrix

The MRD1G5MA designation identifies the specific digital protection relay variant within the Woodward High-Tech Line / High-Line protective relay family:

• MRD1: Base digital protection relay model engineered for directional/non-directional overcurrent and earth fault monitoring.
• G: Standard hardware generation and casing layout.
• 5: 5 A nominal current input secondary rating (selectable options cover 1 A / 5 A).
• MA: Specific auxiliary power supply and output contact hardware configuration.

Hardware Specifications

Actuator Loop Feedback Response and Thermal Dissipation Profiles

Operating with an advanced digital signal processor (DSP), the MRD1G5MA continuously samples AC current waveforms across 50/60 Hz power circuits. The processing architecture evaluates real-time current magnitudes against programmed trip thresholds (0.5 to 20 x In) and earth fault trip limits (0.01 to 2 x In) within a 0.1 to 20 s adjustable time delay envelope. Fast signal conditioning maintains high-speed actuator loop feedback response when driving external breaker trip coils via four 250 VAC / 8 A output relay contacts. Internal power supply components are designed to balance thermal heat sink dissipation profiles across wide AC/DC auxiliary voltage ranges (24-270 VDC / 24-230 VAC).

Frequently Asked Questions

Q: What auxiliary voltage levels are supported by the MRD1G5MA power supply?

A: The relay accepts a wide-range universal auxiliary power supply supporting 24-270 VDC or 24-230 VAC.

Q: What are the current ratings and trip contact limits for the output relays?

A: The unit incorporates 4 changeover output contacts rated for a maximum switching voltage of 250 VAC at an 8 A continuous resistive load.

Q: How is the nominal current input secondary rating configured on this relay?

A: The current input channels accommodate standard secondary CT outputs, selectable for either 1 A or 5 A nominal current (In).

Field Installation Guidelines

• Verify that auxiliary power and CT secondary wiring are de-energized before making physical connections to the rear terminal block.
• Short-circuit all secondary current transformer (CT) leads prior to disconnecting or servicing the relay input terminals to avoid dangerous high-voltage transients.
• Ground the protective earth (PE) terminal directly to the panel earth bus bar using a short, low-impedance grounding conductor.
• Mount the 144 mm x 72 mm x 130 mm housing into a standard panel cutout, securing mounting clamps to preserve mechanical stability and dust seal integrity.