CompactLogix Power Supply Overview
The Allen-Bradley 1768-PA3 is a CompactLogix power supply module built to energize the backplane and keep every attached module running. If your line is down because a power supply failed, this is the module that gets you back up. It accepts a wide input range of 85…265V ac or 108…132V dc, so it fits most industrial power environments without extra conditioning.
This unit belongs to the 1768 CompactLogix family and works with controllers such as the 1768-L43, 1768-L43S, 1768-L45, and 1768-L45S. It is a dual-input supply with an open-style enclosure and DIN rail or panel mounting.
Key Specifications That Matter
| Parameter | Value |
|---|---|
| Input Power | 85…265V ac; 108…132V dc |
| Input Frequency | 47…63 Hz (85…265V ac) |
| Backplane Current | 1.4 Amps at 24 Volts |
| Max Input Power | 120 VA/120 W |
| Efficiency | 75% Typical |
| Max Inrush Current | 50 A @ 85…132V ac; 80 A @ 195…265V ac |
| Power Dissipation, Max | 30 W |
| Isolation Voltage | 30 Volts Continuous |
| Enclosure | None (open-style) |
Why the Input Range Matters
The 85…265V ac and 108…132V dc input range means the same module works across low and high voltage categories. That flexibility reduces spare-part variety on your shelf.
Backplane Power Delivery
The 1768-PA3 supplies 1.4 Amps at 24 Volts to the backplane. This powers module circuitry only — it does not supply output power to output modules. Size your bank accordingly.
Where the 1768-PA3 Fits
This supply suits CompactLogix racks in oil and gas, water treatment, and general factory automation. In a pump station, it keeps the controller and I/O alive through voltage sags. In a packaging cell, the wide input range handles brownouts without a separate regulator. For retrofit projects, it drops into existing 1768 racks with minimal rework.
Installation and Compatibility Notes
Install a 1768 CompactLogix controller in the same bank as the power supply before powering up. Never install a 1769 power supply to a 1768 CompactLogix backplane. The module uses 14 to 22 AWG stranded or solid copper wire. A single LED indicator shows status: green means power is applied; off suggests no input power, a short, or an overload; red points to invalid backplane output or a defective controller or communication module.
Comparison: 1768-PA3 vs. Similar Power Supplies
| Feature | 1768-PA3 | Typical 1769 Supply |
|---|---|---|
| Family | 1768 CompactLogix | 1769 Compact I/O |
| Input | 85…265V ac; 108…132V dc | 85…265V ac |
| Backplane Current | 1.4 A at 24 V | Varies by model |
| Mounting | DIN rail or panel | DIN rail |
| Compatibility | 1768 controllers | 1769 controllers |
Choosing the wrong family causes backplane faults. Confirm your controller series before ordering.
Selection Checklist
Before you buy, verify your controller model, bank size, and input voltage category. If you run 1769 I/O in the same bank, the 1768-PA3 supports up to eight modules. Need hands-on help matching this supply to your rack? Contact Oil AutoTech today for pricing and availability.
FAQ
What input voltage does the 1768-PA3 accept?
It accepts 85…265V ac or 108…132V dc, with an input frequency range of 47…63 Hz on AC.
How much backplane current does it provide?
The module supplies 1.4 Amps at 24 Volts to the backplane.
Which controllers work with this power supply?
It works with 1768 CompactLogix controllers including the 1768-L43, 1768-L43S, 1768-L45, and 1768-L45S.
Can I use a 1769 power supply in a 1768 rack?
No. Never install a 1769 power supply to a 1768 CompactLogix backplane.
What does a red LED indicate?
A red LED may mean invalid backplane output, a controller that needs replacement, or a defective communication or motion module.
