Allen-Bradley 1790-0W8X 8-Relay Output Expansion Module Overview

Product Introduction

When your control system requires additional discrete outputs for switching loads such as solenoids, indicators, or small motors, the Allen-Bradley 1790-0W8X provides a reliable and compact solution. This 8-relay output expansion module integrates seamlessly into Allen-Bradley automation architectures, delivering Form A, normally open, single-pole single-throw contacts. Each relay is rated for 5…24V dc at 2.0 A resistive or 30V ac at 2.0 A resistive, making it versatile for both DC and AC applications. The module is designed for engineers who need predictable switching performance with minimal maintenance.

Technical Specifications Breakdown

The 1790-0W8X offers clear, measurable performance characteristics. The output voltage range is load-dependent: 5…24V dc at 2.0 A resistive, and 30V ac at 2.0 A resistive. The output current rating matches these voltages at 2.0 A for both DC and AC resistive loads. Switching speed is defined by an output delay time of 10 ms maximum for both Off-to-On and On-to-Off transitions, ensuring consistent timing in control sequences. The field power supply requires 24V dc nominal, with a voltage range of 19.2…28.8V dc. Isolation between I/O and logic is provided by photocoupler isolation, rated at 1250V ac rms, protecting your control system from voltage transients. These specs make the module suitable for demanding industrial environments where electrical noise and isolation are critical.

Industry Applications

In automated assembly lines, the 1790-0W8X can control pneumatic valves or conveyor actuators. For example, a packaging machine might use eight relays to sequence clamp, fill, seal, and eject stations. The 10 ms delay ensures synchronized operation without race conditions. In material handling systems, the module switches motor starters or warning lights, leveraging its 2.0 A rating for inductive loads (100 Kcycles expected life). The photocoupler isolation prevents ground loops in mixed-voltage panels, a common pain point in retrofit projects. This module is also ideal for upgrading older relay panels where space is limited, offering a compact 37-pin D-shell connector interface.

Installation & Setup Guidance

Mount the 1790-0W8X on a DIN rail within the allowed ambient temperature range (not specified in data; follow standard industrial practices). Connect field power (19.2…28.8V dc) to the designated terminals, observing polarity. Wire loads to the Form A contacts: each relay is a single-pole, single-throw normally open switch. Use the 37-pin D-shell connector for I/O wiring; ensure the mating connector is properly strain-relieved. Verify that the total load current per channel does not exceed 2.0 A resistive. For inductive loads, add a flyback diode across the load to suppress voltage spikes and extend contact life. After wiring, power up and test each channel sequentially using the eight green status indicators.

Maintenance & Reliability

The 1790-0W8X is built for long service life with expected contact life of 300 Kcycles resistive and 100 Kcycles inductive. Routine inspection should focus on connector integrity and visual condition of the status LEDs. No internal adjustments are required. Keep the enclosure free of dust and moisture to maintain isolation performance. The photocoupler isolation (1250V ac rms) provides robust protection against transient overvoltages, reducing the risk of logic-side damage. For maximum reliability, operate within the specified voltage range (19.2…28.8V dc) and avoid exceeding the 2.0 A per-channel rating. If a relay fails, replace the entire module—field repair is not recommended.

Selection Guide & Purchasing Advice

Before ordering the 1790-0W8X, confirm that your controller supports expansion modules via the 37-pin D-shell interface. Verify that the field power supply can deliver 19.2…28.8V dc at the required current (10 mA per channel at 28.8V dc). For applications requiring higher current or different contact configurations, consider alternative Allen-Bradley modules. BluePLC Industrial stocks the 1790-0W8X and can advise on compatibility with your existing system. Contact our team for current availability and pricing. For complete technical specifications, please contact BluePLC Industrial.