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Industrial Automation & Network Hardware
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The CompactLogix Power Supply Selection Guide

May 28, 2025

Allen-Bradley’s CompactLogix power supplies are designed to power CompactLogix controllers and associated I/O modules. There are two key power supply families:

  • 1768 CompactLogix Power Supplies

  • 1769 Compact I/O Power Supplies

These are engineered to support specific controllers 1768 and 1769 series, ensuring optimal power distribution and system reliability.

Power Supply Specifications

1. Supply Type

  • 1768: Offers dual (AC/DC) and single input options

  • 1769: Single input only

2. Input Voltage

  • AC/DC Ranges:

    • 1768-PA3: 108–132V DC or 85–265V AC

    • 1768-PB3: 16.8–31.2V DC

    • 1769-PA2 / PB2: 19.2–31.2V DC / 85–265V AC

    • 1768-PA4: Selectable 85–265V or 170–265V AC

3. Input Frequency

  • AC models: 47–63 Hz

4. Output Voltage & Current

  • 1768: 3.5A @ 24V DC (e.g., PA3)

  • 1769:

    • PA2/PB2: 2A @ 5V, 0.8A @ 24V

    • PA4/PB4: 4A @ 5V, 2A @ 24V

External Output Terminals

  • Available on: 1768-PA3, 1768-PB3, 1769-PA2

5. Power Ratings

Catalog No Power Consumption Power Dissipation
1768-PA3 120 VA / 120W 30W
1768-PB3 112W 22W
1769-PA2 100–130 VA 8W
1769-PB2 50 VA 7.5W
1769-PA4 200–240 VA 18W
1769-PB4 50 VA 14.5W

6. Overcurrent Protection

  • 1768: 15A internal, soldered (non-replaceable)

  • 1769: Replaceable fuses

    • PA2/PA4: 3.15A fuse

    • PB2/PB4: 6.3A fuse

7. Inrush Current

Catalog No Max Inrush Current
1768-PA3 50A @ 85–132V AC, 80A @ 195–265V AC
1768-PB3 50A @ 16.8–31.2V DC
1769-PA2 25A @ 132V AC
1769-PB2 30A @ 31.2V DC
1769-PA4 25A @ 132V AC
1769-PB4 30A @ 31.2V DC

8. Status Indicators (PWR LED)

  • OFF: No/low input or fault

  • GREEN: Normal

  • RED: Fault, low 24V output

9. Ride-Through & Hold-Up Time

  • Ride-through: 5–25 ms

  • Hold-up: 5–10 ms

Installation Guidelines

Positioning

  • 1768: Leftmost module (right-side power distribution)

  • 1769: Can power from both sides (up to 8 I/O modules each side)

Distance Rating

  • 1768: No rating (1769 I/O modules have distance rating from controller)

  • 1769: 8 modules per bank, 2 banks max (16 modules total)

Environmental Ratings

  • Operating Temp: 32°F to 140°F

  • Storage Temp: -40°F to 185°F

  • Temperature Codes: T3C, T4, T5

Physical Dimensions

Catalog No Weight (lbs) Dimensions (mm)
1768-PA3 / PB3 2.15–2.22 131.25 x 132.75 x 105.50
1769-PA2 / PB2 1.16 118 x 70 x 87
1769-PA4 / PB4 1.39 118 x 70 x 87

Controller vs. Compatible Power Supplies

Controller 1768-PA3 1768-PB3 1769-PA2 1769-PB2 1769-PA4 1769-PB4
1768-L43 ✔ ✔        
1768-L45 ✔ ✔        
1769-L30ER     ✔ ✔ ✔ ✔
1769-L33ER     ✔ ✔ ✔ ✔
1769-L37ERM     ✔ ✔ ✔ ✔
1769-L38ERM     ✔ ✔ ✔ ✔
1769-L35E     ✔ ✔ ✔ ✔

How to Select a Power Supply

  1. Identify the Controller Type: 1768 or 1769 CompactLogix

  2. Match Power Supply: Use compatibility table above

  3. Estimate Required Units:

    • For 1769 controllers:

      • One 1769 power supply for controller + local I/O

      • One 1769 power supply per additional I/O bank

    • For 1768 controllers:

      • One 1768 power supply for controller + 1768 modules

      • One 1769 power supply per I/O bank

  4. Use External Fuse (for 1768 supplies): Add inline replaceable fuse for added safety

  5. Verify Installation Specs: Distance rating, panel position, current draw, etc.

Conclusion Allen-Bradley’s CompactLogix power supplies provide reliable, efficient, and protected power for your automation system. Their high efficiency, safety features, and flexibility make them ideal for powering 1768 and 1769 series controllers and I/O modules.

Need Help Sizing or Selecting a CompactLogix Power Supply?
Contact us today:

PLG Automation
Email: sales@plgautomation.com
Phone: 800-906-9271