The Evolution of ControlLogix Power
Industrial automation has moved from bulky centralized panels to modular, rack-based control architectures. The Allen-Bradley 1756-PB75 ControlLogix power supply reflects that shift. It delivers regulated backplane power to chassis-mounted modules, keeping processors, I/O, and communication cards running from a single 24VDC feed.
This standard power supply mounts on the left side of a compatible 1756 chassis. It accepts 18-32VDC input and produces 75 W of output power at 0…+60 °C. For plants running 24VDC control power, it is a practical, ready-to-ship replacement or expansion module.
Key Parameters That Matter
| Specification | Value |
|---|---|
| Input voltage range | 18-32VDC |
| Nominal input | 24VDC |
| Output power | 75 W @ 0…+60 °C |
| Current capacity | 1.5 A at 1.2VDC; 4 A at 3.3VDC; 13 A at 5.1VDC; 2.8 A at 24VDC |
| Input power | 95 W |
| Hold-up time | 35 ms @ 18VDC; 40 ms @ 24VDC; 40 ms @ 32VDC |
| Isolation voltage | 250V continuous, reinforced insulation |
| Max inrush current | 30 A |
| Dimensions | 14.0 x 11.2 x 14.5 cm |
| Weight | 0.95 kg |
The 13 A at 5.1VDC rail is the workhorse here. It feeds the backplane logic and I/O modules that demand the most current. The 2.8 A at 24VDC output supports modules needing higher voltage, while the 4 A at 3.3VDC and 1.5 A at 1.2VDC rails cover low-voltage logic. Hold-up time of 35-40 ms gives the system a buffer against brief input dips, which helps prevent nuisance shutdowns in electrically noisy plants.
Where the 1756-PB75 Fits
Oil and gas facilities often run 24VDC control power because it is safer and easier to back up than AC. The 1756-PB75 matches that infrastructure directly. In a compressor station, it can power a ControlLogix chassis handling analog inputs from pressure transmitters and discrete outputs to solenoid valves. The wide 18-32VDC range tolerates the voltage sag common on long DC distribution runs.
In water treatment or pipeline monitoring, the same supply supports remote racks where input voltage may drift. The reinforced insulation and 250V continuous isolation help separate field power from backplane logic, reducing noise coupling.
Installation and Wiring Notes
The 1756-PB75 installs at the left-most slot of a compatible chassis. Rockwell specifies 2.5 mm² (14 AWG) solid or stranded copper wire with 90 °C insulation or higher. Maximum insulation thickness is 1.2 mm. Tighten the terminal screw to 0.565 N-m (5 lb-in).
Verify input polarity before energizing. The supply has no enclosure, so mount it inside a protective panel. Keep the chassis within the 0-60 °C operating range and avoid condensing humidity above 95%.
Compatibility and Selection
The 1756-PB75 works with Series B and Series C chassis: 1756-A4, 1756-A7, 1756-A10, 1756-A13, and 1756-A17. Confirm your chassis series before ordering. If you are expanding an existing ControlLogix rack, match the power supply to the total backplane current draw of all installed modules.
For hands-on technical selection help, contact Oil AutoTech. The team supports fast dispatch, worldwide, for oil, gas, and industrial automation spares.
Please verify current lifecycle status and availability with Oil AutoTech before ordering.
