I/O modules

Product Overview

The Allen-Bradley 1794-OW8 FLEX I/O Relay Output Module provides 8 isolated Form A (normally open) electromechanical relay outputs. Designed for the FLEX I/O system, it delivers reliable switching performance for AC and DC loads while maintaining compact installation. This module is ideal for industrial automation systems requiring high-density relay output solutions with robust isolation.

Key Features

• 8 electromechanical relay outputs in one group.
• Supports AC and DC resistive loads with pilot duty ratings.
• Compact design mounts directly on FLEX I/O terminal base units.
• Built-in status indicators for each output channel.
• Provides basic insulation between relays, backplane, and power.
• Extended durability with 100,000 operations at rated load.

Technical Specifications

General Specifications

• Outputs per Module: 1 group of 8 Form A relays (NO, isolated)
• Module Location: Compatible with 1794-TB2, 1794-TB3, 1794-TB3S, 1794-TBN, 1794-TBNF
• Off-State Leakage: Max 1.0 mA at 240V AC
• Minimum Contact Load: 100 µA at 100 mV DC
• Flexbus Current: 5V DC, 35 mA

Power and Voltage Ratings

• Supply Voltage: 24V DC, 125 mA (1794-OW8)
• Voltage Range: 19.2…31.2V DC, 125 mA (1794-OW8XT)
• Relay Contact Ratings:
  • 250V AC, 2 A, resistive load, 50/60 Hz
  • 120/240V AC, pilot duty (1800V A make, 180V A break)
  • 5…30V DC, 2 A, resistive load
  • Pilot Duty: R150, 28V A (max 1 A below 28V DC)

Performance

• Output Signal Delay: 10 ms (ON/OFF)
• Contact Resistance: Max 30 mΩ
• Switching Frequency: Max 0.3 Hz at rated load
• Bounce Time: Avg. 1.2 ms
• Expected Contact Life: Min 100,000 operations at rated load

Thermal and Power

• Thermal Dissipation: Max 18.8 BTU/hr
• Power Dissipation: Max 5.5 W

Isolation and Safety

• Isolation Voltage:
  • 250V continuous (relay-to-relay, relay-to-backplane, relay-to-power)
  • 50V continuous (power-to-backplane)
• Type-tested Isolation:
  • 1500V AC, 60s (relay-to-relay)
  • 3250V DC, 60s (relay-to-backplane, relay-to-power)
  • 720V DC, 60s (power-to-backplane)
• Fusing: Recommended 3.0 A, 250V AC slow-blow fuse (Littelfuse 239003)

Indicators and Physical

• Status Indicators: 8 yellow LEDs
• Keyswitch Position: 9
• Dimensions (HxWxD): 94 x 94 x 69 mm (3.7 x 3.7 x 2.7 in.)
• Weight: Approx 0.3 kg
• Enclosure: Open-style
• Wiring Category: Follow Industrial Automation Wiring Guidelines

Applications

The Allen-Bradley 1794-OW8 is widely used in industries requiring reliable relay output switching, such as:

• Manufacturing automation
• Material handling systems
• Packaging lines
• Process control systems

Details