New AB 1769-PA2 CompactLogix Power Supply 1769PA2 in Box

Allen-Bradley 1769-PA2 | Compact I/O AC Power Supply Module — 85–265V AC / 2.0A @ 5V DC / 0.8A @ 24V DC / 16-Module Capacity

Power Supply for the 1769 Compact I/O Bank

The 1769-PA2 is the AC-input power supply module for Allen-Bradley's 1769 Compact I/O system. Every bank of 1769 Compact I/O modules requires a power supply — this is the module that converts the panel's mains AC supply into the 5V DC and 24V DC that the Compact I/O modules require to operate.

The power supply's module distance rating of 8 defines how far its power distribution reaches: up to 8 I/O modules to the left and 8 to the right — 16 modules in total per power supply bank. For a bank with more than 16 modules, or where power capacity is exceeded before reaching 16 modules, an additional power supply is added to extend the bank.

The current output splits between two rails: 2.0A at 5V DC powers the module logic and backplane communication (the I/O module electronics). 0.8A at 24V DC powers 24V DC field devices and output circuits connected to the I/O modules. Each module in the bank draws from both rails according to its specification — the total draw across all modules in the bank must not exceed these limits in either rail.

A wide input voltage range (85–265V AC) and a recessed slide switch for selecting 120V or 240V nominal operation makes the 1769-PA2 compatible with both North American and international panel supply standards without additional transformers.

Key Specifications

Backplane Connection — No Cables Required

The 1769-PA2 connects to the 1769 Compact I/O backplane through a tongue-and-groove side locking mechanism built into the module's left and right sides. The module slides and locks into the adjacent I/O module or controller, and the backplane power and bus connections are made through these side connectors. No cables, jumpers, or wiring between modules is required for power distribution within the bank — the side connectors handle it.

This same side connector mechanism allows the power supply to distribute power in both directions — to I/O modules installed on its left side and on its right side simultaneously, up to the 8-module distance rating per side.

FAQ

Q1: What is the difference between 1769-PA2 and 1769-PA4?

Both are AC-input 1769 Compact I/O power supplies. The PA2 provides 2.0A at 5V DC and 0.8A at 24V DC. The PA4 provides 4.0A at 5V DC and 2.0A at 24V DC — double the current capacity. Use the PA4 for larger banks with higher total module current draw, or where the 24V DC field power requirement exceeds 0.8A. Calculate the total 5V and 24V draw of all modules in the bank before specifying.

Q2: How is the 120V/240V input selection made on the 1769-PA2?

A recessed slide switch on the module front or top (accessible with a screwdriver to prevent accidental switching) selects between 120V and 240V AC nominal input. Verify and set this switch to match the panel's supply voltage before connecting mains power. The wide 85–265V AC input range means the module tolerates significant voltage variation around either nominal setting.

Q3: The bank has 10 I/O modules — can one 1769-PA2 power all of them?

The distance rating of 8 modules per side limits the physical reach of the power supply, not just the current capacity. With 10 modules in a single direction from the power supply, the 9th and 10th modules are beyond the distance rating and may not receive adequate power. Position the power supply within 8 modules of the furthest module in either direction, or add a second power supply to extend the bank. For banks where the total current draw also approaches 2.0A at 5V DC or 0.8A at 24V DC, verify the current budget as well.

Q4: Does the 1769-PA2 have overload or short-circuit protection?

Yes. An internal fuse (Wickmann 19195-3.15A or equivalent) provides short-circuit and overload protection on the AC input. The fuse is an internal component — it is not user-replaceable in the field. If the fuse is blown by an upstream fault, the power supply requires replacement or factory service. Address the root cause of the overload or short circuit before installing a replacement module.

Q5: Is the 1769-PA2 compatible with CompactLogix as well as MicroLogix systems?

Yes. The 1769-PA2 powers 1769 Compact I/O modules in both CompactLogix and MicroLogix 1500 configurations. For MicroLogix 1500, Compact I/O expansion banks require a 1769 power supply unless the modules are mounted directly adjacent to the MicroLogix 1500 base unit (which provides its own power to the directly adjacent modules). Confirm the specific power supply requirements from the MicroLogix 1500 or CompactLogix system design documentation.