Allen-Bradley 1746-OW8 Relay Output Module

1746-OW8 SLC 500 8-Channel Output Module

Product Introduction

The Allen‑Bradley 1746‑OW8 expands the SLC 500 controller family with eight normally open (N.O.) relay contact outputs. This digital output module handles operating voltages from 5–265V AC or 5–125V DC, making it exceptionally versatile for mixed-voltage control panels. Furthermore, its two output groups each contain four channels per common, allowing independent voltage sourcing for different field devices.

This 1746‑OW8 module directly drives motors, solenoids, valves, and indicator lamps without requiring external interposing relays. Consequently, you reduce wiring complexity and panel footprint. Meanwhile, the module supports both fixed and modular SLC 500 hardware styles. For instance, it works seamlessly with SLC 5/01, 5/02, 5/03, 5/04, and 5/05 controllers. Additionally, remote I/O chassis configurations are supported, provided slot 0 holds a communication adapter.

Key Technical Specifications

The 1746‑OW8 offers eight relay outputs divided into two groups of four points each. Each group shares a common terminal, enabling operation at different voltages simultaneously. For example, group 1 might switch 120V AC loads while group 2 handles 24V DC circuits. The per-output current rating is 1.5 amps at 120V AC and 1.2 amps at 24V DC.

Backplane current consumption measures 85 mA at 5V DC and 90 mA at 24V DC. Total module current capacity reaches 16A AC continuously, with 8A maximum per group. Signal delay for resistive loads is 10.0 ms for both ON and OFF transitions, ensuring predictable switching performance. The step response is 60 ms in and 2.5 ms out.

Thermal dissipation for the 1746‑OW8 is 3.7 Watts maximum, with only 0.138 Watts dissipated per point. This low heat output allows dense module population in the chassis. Additionally, the module's operating temperature spans -25 to 60 °C, while non-operating temperature extends from -40 to 85 °C. Relative humidity tolerance is 5–95% non-condensing.

Mechanical and Environmental Ratings

The 1746‑OW8 is supplied as open-type equipment intended for industrial environments. It operates reliably under vibration of 2g at 10–500 Hz and withstands operating shocks of 30g. Pollution degree must not exceed Pollution Level 2 as defined in EN/IEC 60664-1, especially when installed in Zone 2 hazardous locations. Class 1, Division 2 certification further qualifies the 1746‑OW8 for use in specific industrial settings.

Only qualified personnel should access the enclosure, using tools or appliances for entry. Never disconnect the equipment while power is applied or in a hazardous area, as this may create dangerous electric arcs. Periodic inspection is recommended to maintain long-term reliability.

Installation and Group Configuration

Installing the 1746‑OW8 is straightforward. First, ensure the chassis power is completely removed. Then, slide the module into any available slot in the SLC 500 rack—it occupies just a single slot regardless of placement. Secure the module firmly against the backplane connector.

Each of the two output groups on the 1746‑OW8 has four channels sharing a common return. This group architecture lets you apply different voltage sources to each group, eliminating external interposing relays. For inductive loads, install surge suppression devices (such as varistors or RC snubbers) across the load to prolong relay contact life. Always consult the user manual for detailed wiring diagrams and terminal assignments.

Packaging and Shipping

Every Allen‑Bradley 1746‑OW8 module is packaged in anti-static material to prevent electrostatic damage during transit. The package contains the module only; terminal blocks, mounting hardware, and cables are sold separately. We ship all orders via FedEx, UPS, or DHL with full tracking capabilities for worldwide delivery.

Frequently Asked Questions (FAQ)

1. Can the two groups on the 1746-OW8 operate at different voltages?
Yes, each group on the 1746‑OW8 has an independent common terminal. Therefore, group 1 can run at 120V AC while group 2 operates at 24V DC simultaneously.

2. What is the maximum total current for the 1746-OW8 module?
The 1746‑OW8 supports 16A continuous current per module, with each group limited to 8A maximum. Per-output limits are 1.5A at 120V AC or 1.2A at 24V DC.

3. Does the 1746-OW8 require external interposing relays?
No, the 1746‑OW8 eliminates the need for interposing relays because it directly supports mixed AC/DC voltages within its two isolated groups.

4. Which SLC 500 processors are compatible with the 1746-OW8?
The 1746‑OW8 works with SLC 5/01, 5/02, 5/03, 5/04, and 5/05 controllers, as well as in remote I/O chassis with a communication adapter in slot 0.

5. What surge protection is recommended for the 1746-OW8?
Install external surge suppressors like RC snubbers or metal-oxide varistors across inductive loads to protect the 1746‑OW8 relay contacts from voltage spikes.