General Information

Core Description

Designed for flexible load switching across industrial logic networks, the 1746-OW16 is an Allen-Bradley SLC 500 digital output module equipped with 16 electromechanical relay contact points grouped into 8 channels per common. Operating across wide voltage categories from 5 to 125V DC or 5 to 265V AC, it features electro-optical isolation rated up to 1500V between the I/O terminals and internal control logic. This high-density module delivers a maximum turn-on and turn-off response of 10.0 ms under resistive loads, providing safe separation between high-voltage plant power and the low-voltage processor backplane.

Specific Application

• Multi-Voltage Load Multiplexing: Controlling field devices that run on completely different voltage ratings (e.g., mixing 24V DC pilot lights and 120V AC motor contactors) across the same output card.
• Low-Leakage Control Circuits: Switching high-impedance interlock strings where solid-state triac leakage current could cause false-on errors or prevent external relay dropouts.

Ordering Information

System Compatibility

• System Compatibility: The 1746-OW16 module slides independent of slot position into any standard SLC 500 hardware chassis, consuming a backplane current of 0.170 A at 5V DC and 0.180 A at 24V DC. Field wiring lands on a built-in removable terminal block that accommodates up to 14 AWG stranded wire with 3/64-inch insulation, fastened up to a maximum torque of 0.9 Nm. For retrofitted systems using older PLC racks, it accepts an Octal Label Conversion Kit ordered to swap standard decimal faceplates with an octal system matching PLC-5 addressing.
• Direct Application Alternates: 1746-OX8 (Individually Isolated 8-Point Relay Module) and 1746-OA16 (16-Point 100-240V AC Triac Output Module).
• Key Differences from Alternates (1746-OW16 vs. OX8 / OA16):
• Commoning Group Architecture: The 1746-OW16 offers a high 16-point density divided across 2 commons (8 points per common), which saves backplane physical space. In contrast, the 1746-OX8 provides only 8 points, but each channel is fully isolated with its own independent common, making the OX8 better suited for switching completely unlinked power sources or separate phases per point.
• Solid-State vs. Hard Contacts: While the 1746-OA16 features solid-state triac outputs engineered for high-duty cycling without physical wear, it suffers from a 2 mA off-state leakage current and only switches AC power. The 1746-OW16 utilizes true mechanical relay contacts with 0 mA off-state leakage, allowing it to switch both AC and DC networks smoothly, though restricted by physical life cycles and a 10 g operating shock limit.

Installation & Troubleshooting FAQ

Q1: What are the absolute maximum voltage and continuous current limits per common for a 1746-OW16?

A: The 1746-OW16 handles an operating range up to 265V AC or 125V DC. The absolute continuous current limit is 8.0 A per common. When planning your field loading, the total combined continuous current for the entire module must be restricted so that the overall heat and load do not exceed 1440 VA to prevent overheating the card assembly.

Q2: Why are the mechanical relay contacts on my 1746-OW16 burning out prematurely when switching solenoids?

A: This is caused by inductive back-EMF spikes generated when current to an inductive field load (like a solenoid or contactor coil) is interrupted. To extend the life of your SLC 500 relay contacts, you must connect external surge suppression across your external inductive load. For AC loops, an RC network or varistor is required; for DC loops, landing a reverse-wired diode across the load will absorb the voltage spikes and safeguard the module.

Q3: Can I hot-swap a 1746-OW16 or remove its wiring block while the SLC 500 chassis is powered?

A: No. You must never install, remove, or wire modules with power applied to the chassis. Removing or adjusting the removable terminal block while the SLC 500 system is energized risks exposing personnel to dangerous AC line potential, which may cause personal injury, and could cause immediate module damage or unexpected equipment operation.

Q4: What are the specific environmental enclosure constraints required to deploy a 1746-OW16 in a industrial environment?

A: The 1746-OW16 is certified as open-type equipment intended for a Pollution Degree 2 industrial environment and overvoltage Category II applications up to 2000 meters. It must be mounted within a tool-accessible enclosure featuring suitable flame-retardant properties complying with a 5VA flame spread rating to prevent accessibility to live components and maintain an ambient air temperature between 0 and 60 °C.

Q5: Is the 1746-OW16 safe for environments exposed to harsh atmospheric chemicals?

A: You must exercise caution because exposure to certain industrial chemicals can cause material degradation. Specifically, chemical vapors may degrade the sealing properties of the Relay Epoxy compounds used inside the module. It is highly recommended that you periodically inspect the physical module casing for any degradation of properties and immediately replace the unit if any material breakdown is detected.

Certification

UKCA DOC

This product was certified with the above certifications as of {}. Products sold before or after this date might carry different certifications. Please review the product label to check for the certifications your specific product carries.