Product Overview

The Allen-Bradley 1771-OZL is a specialized digital relay output module designed for the PLC-5 platform, utilizing advanced dry-reed relay technology to provide highly reliable switching for low-power circuits. This module features eight Form A (Normally Open) contacts, which are architecturally separated into four isolated groups. Each group possesses its own independent common, allowing for the concurrent control of different voltage potentials and ensuring maximum circuit flexibility within a single 1771 chassis slot.

Engineered for precision and longevity, the 1771-OZL is optimized for applications requiring high signal integrity and low contact resistance. Unlike standard mechanical relays, the dry-reed components are hermetically sealed, protecting the contact surfaces from oxidation, dust, and corrosive industrial gases. This makes the module an ideal choice for instrumentation loops and sensitive pilot-duty control.

Core Technical Characteristics

The 1771-OZL is distinguished by its high-speed operation and superior electrical isolation.

• Hermetically Sealed Reed Relays: The vacuum-sealed contacts ensure consistent performance in harsh environments and enable significantly faster switching speeds than traditional electromechanical relays.

• Four-Group Isolation: Provides 1500V RMS galvanic isolation between groups and from the backplane, protecting the PLC processor from field-side electrical noise or transients.

• Low-Level Signal Switching: Specifically rated for low-power tasks, handling 0 to 24V AC/DC at a maximum of 100 mA per point, making it perfect for interfacing with high-impedance electronic inputs.

• Visual Diagnostics: The front panel is equipped with eight red LED status indicators, providing immediate verification of each individual relay's energized state for rapid field troubleshooting.

• High Reliability: The solid-state-like reliability of reed relays provides millions of operations under rated loads, reducing maintenance requirements for critical control loops.

Technical Specifications

• Manufacturer: Allen-Bradley (Rockwell Automation)

• Model Number: 1771-OZL

• Output Type: Dry-Reed Relay (Form A, Normally Open)

• Number of Outputs: 8 Points (Isolated in 4 groups of 2)

• Operating Voltage: 0–24V AC/DC

• Continuous Current: 100 mA per point (Non-inductive)

• Backplane Current Draw: 450mA @ 5V DC

• Power Dissipation: 3.6 Watts (Maximum)

• Switching Frequency: 100 Hz (Maximum at rated load)

• Operating Temperature: 0°C to 60°C (32°F to 140°F)

• Dimensions: 3.5 x 13.0 x 14.5 cm

• Weight: 0.9 kg (1.98 lbs)

Industrial Applications and Integration

The 1771-OZL serves as a critical interface for low-energy signal management:

• Instrumentation Loops: Switching low-voltage analog signals or digital inputs for laboratory and test equipment.

• Hazardous Area Interfacing: Acting as an interposing relay for intrinsically safe circuits where low energy levels must be maintained.

• Data Acquisition: Routing low-current signals to remote monitoring systems without introducing significant contact resistance.

• Pilot Control: Energizing sensitive electronic indicators and low-power audible alarms.

The module requires a 1771-WG or 1771-WH field wiring arm to facilitate secure connections without removing terminal wiring during module replacement.