Allen-Bradley 1746-OW8 AC/DC Relay Output Module

Allen-Bradley 1746-OW8 AC/DC Relay Output Module

Description

Core Function & Channel Configuration

It features 8 independent relay output channels, with 4 points sharing a common terminal (4 points per common), enabling flexible wiring for multiple load devices.

The module supports both AC and DC loads, with an operating voltage range of 5–265V AC (frequency: 47–63 Hz) and 5–125V DC, making it compatible with a wide range of industrial actuators, solenoids, and other output devices.

Electrical Specifications

Backplane Current Consumption: Draws 0.085 A at 5V DC and 0.090 A at 24V DC from the SLC 500 chassis backplane, ensuring compatibility with standard chassis power supplies.

Signal Delay: Maximum on/off delay of 10 ms (resistive load), suitable for general-purpose industrial control applications that do not require ultra-high-speed switching.

Off-State Leakage Current: 0 mA, eliminating unintended load activation and ensuring safe operation when outputs are de-energized.

Minimum Load Current: Requires a minimum load current of 10 mA at 5V DC to ensure stable relay operation.

Relay Contact Ratings

The relay contacts (Silver Cadmium with Gold overlay, for anti-oxidation and low contact resistance) have the following ratings:

AC Operation: 15 A make / 1.5 A break at 120V AC; 7.5 A make / 0.75 A break at 240V AC; continuous current of 2.5 A; maximum volt-amperes (VA) of 1800 VA (120V AC) and 180 VA (240V AC).

DC Operation: 1.2 A make / 2.0 A continuous at 24V DC; 0.22 A make / 1.0 A continuous at 125V DC; maximum power of 28 VA.

Continuous Current per Module: 16.0 A AC total, with 8.0 A per common terminal, preventing overloading of wiring and components.

Mechanical & Installation Features

Terminal Block: Equipped with a removable terminal block (compatible with Allen-Bradley spare part 1746-RT32) for easy wiring and module replacement without rewiring field devices. Terminal screws accept up to two 14 AWG (2 mm²) wires, with a maximum torque of 0.7–0.9 Nm (6–8 in-lb).

Chassis Compatibility: Installable in any I/O slot (except slot 0, reserved for processors/adapters) of SLC 500 modular chassis or 2-slot fixed expansion chassis (1746-A2), with compatibility verified via the SLC 500 fixed I/O chassis module compatibility table.

Environmental Ratings: Operates in temperatures of 0–60°C (32–140°F), storage temperatures of -40–85°C (-40–185°F), and 5–95% non-condensing humidity. It meets NEMA ICS 2-230 noise immunity standards, 10 G operating shock (relay contact module), and 2.5 G operating vibration (57–2000 Hz), ensuring durability in harsh industrial environments.

Safety & Certification

Hazardous Location Approval: Class I, Division 2, Groups A, B, C, D (UL listed, CSA approved), suitable for non-hazardous and specified hazardous locations when installed per N.E.C. Article 501-4(b).

Isolation: 1500V AC isolation between I/O terminals and backplane, protecting the SLC 500 system from electrical transients in field wiring.

Surge Suppression Recommendation

To extend relay contact life and prevent voltage transients from inductive loads (e.g., relays, solenoids), a 1N4004 diode (for 24V DC loads) or Harris Metal-Oxide Varistor (V220MA2A for 120V AC loads) is recommended, installed directly across the load coil.

Power Dissipation

Minimum power dissipation: 2.59 W (no field power).

Total power dissipation: 3.70 W (all 8 points energized, 0.138 W per point at nominal voltage), aiding in system heat management calculations.

Technical Specifications