Description

Key Technical Specifications

Parameter	Specification	Notes
Module Type	Discrete Relay Output	Isolated contacts
Output Channels	4 Channels	Independent Form-C (SPDT)
Control Voltage	24 V DC	Nominal operating voltage
Input Logic	Positive/Negative Logic	Configurable via jumper/software
Contact Rating	5 A @ 250 V AC	Resistive load
Max Switching Voltage	300 V AC / 60 V DC	Maximum breakdown voltage
Mechanical Life	> 10,000,000 cycles	At no load
Electrical Life	> 100,000 cycles	At full rated load
Operating Temperature	-30°C to +70°C	Derate power above 60°C
Storage Temperature	-40°C to +85°C	Non-condensing
Mounting	DIN Rail or Panel	Standard industrial mounting
Weight	Approx. 0.45 kg	Module only

Product Introduction

The WOODWARD MRR1-D is a discrete relay output module designed for industrial control applications, specifically within turbine and compressor control systems. It serves as the physical interface between the digital logic controller and high-power field devices, such as solenoid valves, alarm horns, or motor starters. By providing four isolated Form-C relay contacts, it allows for flexible switching of both AC and DC loads without requiring intermediate interface relays in many cases.Field experience indicates this module is critical for “hard” safety trips where solid-state outputs are insufficient due to current requirements or isolation needs. The primary advantage of the MRR1-D lies in its galvanic isolation; a fault on the field side (e.g., a shorted solenoid coil) will not damage the low-voltage logic circuitry driving it. With a contact rating of 5 A at 250 V AC, it handles standard industrial loads directly. This reduces panel wiring complexity and potential failure points associated with external relay sockets.

Installation & Configuration Guide

Phase 1: Preparation (10 min)

Verify Compatibility: Check the system schematic to ensure the MRR1-D slot configuration matches the chassis backplane.
ESD Safety: Put on an anti-static wrist strap. Connect it to a grounded metal surface. These modules contain sensitive CMOS logic.
Inspect Hardware: Ensure the DIN rail clips or mounting screws are present and undamaged.

Phase 2: Removal of Old Unit (if applicable) (5–10 min)

Lockout/Tagout: De-energize the control system. Verify zero energy with a multimeter.
Label Wiring: Use a permanent marker or label maker to tag every wire connected to the terminal block. Do not rely on memory.
Disconnect: Unscrew terminal blocks carefully. Do not pull wires by the insulation.
Unmount: Release the locking tab (usually at the bottom of the module) and slide the unit off the rail.

Phase 3: Installation (10 min)

Mounting: Slide the MRR1-D onto the DIN rail until it clicks into place. Tug gently to confirm it is locked.
Wiring: Reconnect wires to the terminal block based on your labels.
- Torque Check: Tighten terminals to 0.5–0.6 Nm. Loose connections cause arcing and heat.
Address Setting: If the module uses rotary switches or DIP switches for node addressing, set them now according to the system manual.

Phase 4: Power-On & Test (10 min)

Visual Check: Ensure no tools or loose wire strands are left inside the cabinet.
Energize: Apply 24 V DC control power.
Status LEDs: Observe the status LED. A steady green typically indicates healthy communication. Red implies a bus error or internal fault.
Forced Output Test: Use the engineering workstation to force each relay ON/OFF individually. Listen for the distinct mechanical “click” of the relay closing. Measure continuity across the common/normally open contacts to verify.

Troubleshooting Quick Reference

Symptom	Probable Cause	Corrective Action
Relay does not click	No control voltage	Measure 24V DC at the input terminals. Check fuses.
LED is Red/Flashing	Communication loss	Check ribbon cable connection to backplane. Verify baud rate settings.
Contacts welded shut	Inductive kickback	Verify flyback diodes are installed on DC solenoids. Replace module.
Intermittent operation	Loose terminal screw	Re-torque all terminal screws. Check for corrosion.
System won’t start	Wrong firmware version	Check part number suffix. Compare with OEM specifications.

Dimensions, Mounting & Wiring Notes

Dimensions: Approx. 115 mm (H) x 75 mm (W) x 120 mm (D).
Mounting: Standard 35 mm DIN Rail.
Wiring Note: Use stranded wire (14–18 AWG) with ferrules for best connection reliability. Avoid solid core wire as vibration can cause it to fracture near the crimp.

FAQ

Q: Can I use this module to switch 110V AC loads?
Yes. The relay contacts are rated for up to 250V AC. However, ensure the current draw of the load does not exceed 5A. If switching inductive AC loads (like small motors), consider using a snubber circuit to protect the contacts from arcing.Q: What does the “-D” suffix mean in MRR1-D?
In Woodward nomenclature, suffixes often denote specific hardware revisions or firmware configurations tailored for certain markets or legacy replacements. Always cross-reference the full part number with your system’s Bill of Materials (BOM) to ensure compatibility.Q: My old module is an MRR1 (no dash). Is this compatible?
Usually, yes. The “-D” revision typically supersedes earlier versions, but you must verify the pinout configuration. Check the wiring diagram on the inside of the module cover or the technical manual before connecting power.Q: How do I know if the module is genuine?
Genuine Woodward modules have high-quality silk screening, clear molded plastic, and a specific weight. Counterfeits often feel lighter and have blurry text. We test every unit on a dedicated rack to verify communication handshake protocols before shipping.Q: Does this come with a warranty?
Yes, we provide a standard 1-year warranty against manufacturing defects. This covers component failure under normal operating conditions but does not cover damage caused by improper installation or power surges.