Purchase now: Allen Bradley 1746-OA16 AC Output Module
Purchase now: Atlantechdrives provides you the 1746-OA16, a robust and high-density digital AC output module manufactured by Allen Bradley for the venerable SLC 500 automation platform. This module is equipped with 16 solid-state output points designed to directly switch alternating current (AC) loads. Operating effectively within a 85 to 265V AC range, it is an essential component for controlling heavy industrial devices such as motor starter coils, high-voltage solenoids, strobe lights, and AC-powered horns. By utilizing solid-state Triac technology instead of traditional mechanical relays, the 1746-OA16 offers millions of cycles of wear-free, rapid switching, significantly extending the lifespan of your control panel hardware in high-cycle packaging and assembly applications.
Technical Specifications of the 1746-OA16
The 1746-OA16 eliminates the need for external interposing relays by allowing the 5V DC PLC processor to safely control dangerous 120V or 240V AC field devices. The outputs are divided into groups to simplify wiring, and the solid-state design ensures zero mechanical bounce during actuation.
- Part Number: 1746-OA16
- Module Type: Digital AC Output Module
- Compatible System: SLC 500 (1746 Chassis)
- Number of Outputs: 16 Solid-State Triac points
- Operating Voltage: 85…265V AC (47…63 Hz)
- Continuous Current per Point: 0.50 Amps at 30°C / 0.25 Amps at 60°C
- Maximum Surge Current: 10.0 A for 25 ms
- Backplane Current Draw: 370 mA at 5V DC
- Isolation: 1500V AC optical isolation
Expert Installation Advice: Managing Triac Leakage Current
When upgrading from mechanical relays to solid-state Triac outputs, engineers often encounter the «Ghost Voltage» phenomenon. Expert Tip: Triacs, by their physical nature, are never 100% «off.» Even when the PLC logic commands the output to be false, a tiny amount of «leakage current» (up to 2 mA for the OA16) continues to flow through the circuit. If you connect a very low-power load to this module—such as a modern, high-efficiency LED indicator light or a low-draw micro-solenoid—this 2 mA of leakage current might be enough to keep the LED dimly lit or prevent the solenoid from fully releasing. To solve this, you must install a «burden resistor» (typically a 10k Ohm, 5 Watt wire-wound resistor) in parallel with the load. This resistor will bleed off the leakage current, ensuring the device turns completely off.
Maintenance and Fusing
The 1746-OA16 does not have internal, replaceable fuses for each point. Because solid-state Triacs will permanently fail (short circuit) if subjected to a dead-short or an extended overcurrent event, it is highly recommended to install external terminal-block fuses (e.g., 1 Amp fast-blow) for each output wire leaving the PLC cabinet. This protects the expensive PLC module from short circuits originating on the factory floor.
Frequently Asked Questions (FAQs)
Q: Can the 1746-OA16 switch 24V DC loads?
A: No. Triacs are alternating current (AC) devices. They rely on the AC sine wave crossing zero volts to turn off. If you pass DC voltage through this module, the output will turn on but will never turn off, resulting in loss of control. For DC loads, use the 1746-OB16.
Q: What is the total current capacity for the whole module?
A: While a single point can handle 0.5A, the entire module is rated for a maximum of 8.0 Amps total continuous current (at 30°C). You must distribute your heavy loads carefully to avoid overheating the backplane.
Do you need more references from this brand? Explore our full catalog of Allen Bradley here.
For 120V AC load switching, this 16-point output module is the ideal companion for the 1746-IA16 AC input card.
