Allen-Bradley 1794-OM8 Technical Overview and Engineering Guide

1. Product Introduction

The 1794-OM8 is an 8-channel relay output module designed for FLEX I/O distributed automation systems. It is used for switching industrial AC and DC loads in applications where electrical isolation, flexible voltage compatibility, and relay-based control are required.

Unlike transistor output modules, the 1794-OM8 uses electromechanical relay contacts, allowing it to control a broader range of field devices including contactors, pilot lamps, solenoids, small motors, and industrial relays.

The module integrates into a modular distributed I/O platform through a FLEX I/O terminal base, making it suitable for decentralized control architectures with reduced field wiring complexity.

2. Product Parameters

Electrical Specifications

Parameter	Specification
Output Type	8-channel relay output
Relay Contact Type	Normally Open (NO)
Switching Voltage	5–250 V AC / 5–125 V DC
Maximum Switching Current	2.0 A per channel
Continuous Current per Module	Up to 8 A total
Contact Resistance	≤ 100 mΩ
Relay Operating Time	~10 ms
Relay Release Time	~10 ms
Mechanical Relay Life	≥ 20 million operations
Electrical Relay Life	≥ 100,000 operations (rated load)
Isolation	Backplane-to-field isolation
Power Supply	24 V DC nominal
FlexBus Current	~90 mA @ 5 V DC
Power Dissipation	~3.8 W
Thermal Dissipation	~13 BTU/hr

Mechanical Specifications

Parameter	Specification
Dimensions (H × W × D)	94 mm × 94 mm × 69 mm
Weight	~0.20 kg
Mounting Method	DIN rail via FLEX I/O terminal base
Compatible Bases	1794-TB2 / TB3 / TB3S / TB3T
Wiring Method	Screw terminal connection
Status Indicators	8 LED output status indicators

Environmental Specifications

Parameter	Specification
Operating Temperature	0 to 55 °C
Storage Temperature	-40 to 85 °C
Relative Humidity	5–95% non-condensing
Vibration Resistance	5 g (10–500 Hz)
Shock Resistance	30 g
Protection Level	IP20 system-level protection

3. Product Features

The 1794-OM8 is engineered for flexible relay-based output switching in industrial automation systems.

8-channel relay output configuration
Supports both AC and DC industrial loads
Electromechanical relay isolation improves compatibility
Independent output status LED indicators
Suitable for mixed voltage applications
Compact modular FLEX I/O architecture
Reliable switching performance in industrial environments
Easy installation and maintenance through terminal base system

The relay output design allows the module to interface with devices that cannot be directly controlled by semiconductor outputs.

4. Product Applications

The module is commonly used in industrial systems requiring relay-based load control, including:

Industrial motor starter control
Solenoid valve operation
Conveyor system automation
Pump and fan switching systems
Industrial alarm and indicator lamp control
HVAC automation equipment
Machine automation and assembly systems
Distributed field control panels

It is especially suitable for applications where multiple voltage types or electrically isolated outputs are required.

5. Product Advantages

Compatible with both AC and DC load switching
Relay isolation improves electrical safety and flexibility
High load adaptability compared to transistor outputs
Compact modular design saves cabinet space
Long relay mechanical service life
LED diagnostics simplify maintenance and troubleshooting
Suitable for mixed industrial load environments
Reduced need for external interposing relays in many systems

6. Series and System Information

Category	Description
Series	FLEX I/O 1794 Series
System Type	Distributed modular I/O platform
Module Type	Relay output module
Architecture	Remote I/O with terminal base system

The FLEX I/O 1794 series provides flexible distributed automation capability by supporting digital, analog, relay, and specialty modules in one scalable architecture.

7. Recommended Modules – Same Series or Related Models

Model	Type	Function	Voltage	Weight (kg)	Dimensions
1794-OM16	Relay Output Module	16-channel relay output	24 V DC	~0.25	94×94×69 mm
1794-OB16P	Digital Output Module	16-point protected DC output	24 V DC	~0.10	94×94×69 mm
1794-OB8EP	Protected Output Module	8-point electronic fused output	24 V DC	~1.0	94×94×69 mm
1794-IB16	Digital Input Module	16-point digital input	24 V DC	~0.10	94×94×69 mm
1794-IE8	Analog Input Module	8-channel analog input	—	~0.18	94×94×69 mm

8. Recommended Popular Modules – Same Platform

Model	Type	Function	Voltage	Weight (kg)	Dimensions
1756-OB16E	Control Output Module	16-channel DC output	24 V DC	~0.30	150×90×100 mm
1756-IB16I	Control Input Module	16-channel isolated input	24 V DC	~0.30	150×90×100 mm
1734-OB8	Compact Output Module	8-channel distributed output	24 V DC	~0.10	56×75×50 mm
1769-IQ16	Compact Input Module	16-channel digital input	24 V DC	~0.25	118×87×40 mm
1769-OB16	Compact Output Module	16-channel digital output	24 V DC	~0.25	118×87×40 mm

9. Engineering Summary

The 1794-OM8 is a compact relay output module designed for industrial automation systems requiring reliable AC/DC load switching and flexible electrical compatibility.

Its primary strengths include relay-based isolation, support for mixed voltage applications, long operational life, and flexible integration into distributed I/O systems.

Compared with semiconductor output modules, it offers broader compatibility with industrial field devices and improved electrical isolation, making it suitable for demanding automation environments where switching flexibility is essential.

Company Information
E-mail		[email protected]
Mobile		+8615980777398
Whatsapp		+8615980777398
WeChat		15980777398

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