Why the 1756-OA16I Belongs in Your Spares Strategy
Downtime on a ControlLogix line rarely waits for a purchase order. The Allen-Bradley 1756-OA16I gives you sixteen individually isolated AC outputs in a single slot, so one module can drive a whole bank of field devices without channel-to-channel interference. For oil, gas and heavy industrial sites, that density plus isolation is exactly what keeps a rack running when a replacement is needed fast.
This is a 1756 ControlLogix discrete AC output module from Allen-Bradley / Rockwell Automation. It delivers 120/240 VAC nominal output across an operating range of 74-265 VAC at 47-63 Hz. Each of the sixteen points is individually isolated, which simplifies mixed-load panels and reduces cross-talk between circuits.
Key Parameters at a Glance
| Specification | Value |
|---|---|
| Outputs | 16, individually isolated |
| Operating voltage range | 74-265 VAC |
| Nominal output voltage | 120/240 VAC |
| Frequency | 47-63 Hz |
| Continuous current per point | 2 A @ 30 °C; 1 A @ 60 °C (linear derating) |
| Continuous current per module | 5 A @ 30 °C; 4 A @ 60 °C (linear derating) |
| OFF-to-ON delay | 9.3 ms @ 60 Hz; 11 ms @ 50 Hz |
| OFF-state leakage | 3 mA per point |
| Backplane current | 300 mA @ 5.1 V; 2.5 mA @ 24 V |
| Power dissipation | 5.5 W @ 60 °C |
| Isolation voltage | 250 V continuous, outputs-to-backplane and output-to-output |
| Terminal blocks | 1756-TBCH, 1756-TBS6H |
| Slot width | Single slot |
What These Ratings Mean on the Plant Floor
Isolation is the headline. With sixteen individually isolated points, a fault or noise event on one output does not bleed into its neighbours. That matters in plants where AC solenoids, contactors and pilot lights share a panel with sensitive signalling.
The derating curve is the second thing to plan around. At 30 °C ambient you can pull 2 A per point and 5 A per module; at 60 °C those figures fall to 1 A and 4 A. Size your load schedule against the real cabinet temperature, not the datasheet headline.
Switching speed is fast enough for most discrete control. An OFF-to-ON transition takes 9.3 ms at 60 Hz and 11 ms at 50 Hz, with matching ON-to-OFF times. The module also supports per-point fault mode and program-mode state configuration, with Hold Last State, On or Off selectable and Off as the default.
Where It Fits
A 1756-OA16I suits panels that switch large numbers of AC field devices from one rack slot. Typical duties include driving solenoid valve banks on a gas metering skid, energising contactor coils on a pump control panel, and running indicator and alarm circuits across a compressor station.
Because each point is isolated, the module also handles mixed 120 VAC and 240 VAC loads within the same 74-265 VAC envelope. That flexibility lets you standardise on one spare instead of stocking several output variants.
Installation and Rack Fit
The module mounts in a single slot of any 1756 chassis, including the 1756-A4, 1756-A7, 1756-A10, 1756-A13 and 1756-A17. You can place it in the local rack alongside the ControlLogix controller or in a remote I/O rack with a 1756 communication adapter.
Wiring lands on a removable terminal block. The compatible RTBs are the 1756-TBCH and 1756-TBS6H, with user-defined keying. The module ships with an open-style enclosure and no internal fusing, so external circuit protection remains part of your panel design. Operating temperature is 0 to 60 °C at 5-95% non-condensing humidity.
Keeping It Running
Inspect terminal block seating and output wiring periodically, and confirm cabinet temperature stays within the derating assumptions you designed for. Because the points are isolated, a single failed channel does not force you to replace the whole module immediately, but keeping a spare on the shelf is the practical move.
That is where Oil AutoTech helps. We supply ready-to-ship ControlLogix spares for oil, gas and industrial automation, with fast dispatch, worldwide. Our team can confirm the correct terminal block and chassis fit for your rack before you order.
Please verify current lifecycle status and availability with Oil AutoTech before ordering.
Choosing the Right Output Module
Before you commit, confirm three things: your load voltage sits inside 74-265 VAC, your per-point and per-module currents fit the derating curve at your cabinet temperature, and your rack has a free single slot with the right RTB on hand. If any of those is unclear, our technical team can walk through the selection with you.
Contact Oil AutoTech today for pricing and availability.
