Allen-Bradley 1769-PA4 CompactLogix AC Power Supply 4 A

The 4 A AC supply for a Compact I/O bank

The Allen-Bradley 1769-PA4 is an AC-input power supply for the 1769 Compact I/O and CompactLogix system. It converts a 120/220V AC supply (85 to 265V AC range) into the 5V DC backplane supply and 24V DC bus used by the controller and the I/O modules in a bank, delivering 4.0 A at 5V DC and 2.0 A at 24V DC.

It is the larger of the two AC types: the 1769-PA2 delivers 2.0 A at 5V DC and 0.8 A at 24V DC. The DC-input counterpart of the 4 A supply is the 1769-PB4, which uses 19.2 to 31.2V DC input and supplies 4.0 A and 1.7 A.

Technical specifications

Sizing a bank with the supply

Add up the 5V DC and 24V DC current draws of every module in the bank and compare them with the supply capacity. Each I/O module sheet lists its draw, for example 170 mA at 5.1V DC for the 32-point input. The supply can feed up to eight I/O modules on each side, for a maximum of 16 modules, but the distance rating of each module can limit this further.

Input consumption is 200VA at 120V AC and 240VA at 240V AC, with an inrush of up to 30 A at 132V AC, so choose protective devices that tolerate the inrush. Power dissipation is 18 W at 60 °C, which matters for cabinet heating.

Installation and grounding

The supply mounts on a DIN rail or panel using M4 or #8 screws at 1.16 N.m, and it measures 118 x 70 x 87 mm and weighs 630 g. Connect 14 AWG (2.5 mm²) solid copper wire rated 90 °C or greater; the wire category for the power ports is 2. IEC Class 1 grounding is required because the isolation is reinforced.

The sheet lists operating temperature as 0 to 60 °C and open-style enclosure rating. A Wickmann or Littelfuse fuse of 6.3 A is listed for the 4 A supplies, and the sheet describes the output derating and power dissipation curves. Select the correct input range before powering up.

Documents and quotation

The power-supply technical data 1769-TD008 gives the full table and derating curves. For a quotation, send the 1769-PA4 reference, series, quantity and the bank module list. Related automation hardware appears in PLC & I/O Cards.

How the 1769-PA4 Works

The 1769-PA4 is a switch-mode power supply that sits in the bank like an I/O module. It takes the AC supply from the panel, rectifies and converts it, and puts two regulated DC rails on the Compact I/O bus: 5V DC for the module electronics and communication, and 24V DC for circuits such as relay coils and analog stages. Every module to its left and right draws from these rails through the bus connectors, so the supply’s position in the bank and its current capacity decide how many modules a bank can hold.

The 5V DC and 24V DC ratings are separate limits, and both must be respected. A bank full of relay output modules may run out of 24V DC capacity before the 5V DC limit is reached, while a bank of communication and analog modules is usually limited by the 5V DC rail.

Selection & Ordering Guide for the 1769-PA4

• 1769-PA4 – AC input, 4.0 A at 5V DC and 2.0 A at 24V DC.
• 1769-PA4K – conformal-coated version for harsh atmospheres.
• 1769-PA2 – smaller AC supply for lightly loaded banks.
• 1769-PB4 and 1769-PB2 – DC-input supplies for panels powered from 24V DC.

Choose the supply by adding up the current draw of the controller or adapter and every I/O module in the bank, then leave a margin for future expansion. If the bank exceeds the supply limits, split it into two banks with a second supply and an expansion cable. Our team can help confirm the correct ordering code when you request a quote.

Installation & Maintenance of the 1769-PA4

• Isolate the AC supply before wiring, and before inserting or removing modules in the bank.
• Connect the protective earth terminal, since the reinforced insulation relies on IEC Class 1 grounding.
• Install upstream protection that tolerates the inrush current, and use the fuse type specified in the Rockwell documentation.
• Leave the recommended ventilation space around the bank; the 18 W dissipation adds noticeably to cabinet heating, which matters in hot plant rooms.
• During maintenance, check terminal tightness, look for discolouration at the input terminals, and confirm the output indicator is lit with the system running.

Typical Applications in Oman & the GCC

The 1769-PA4 powers CompactLogix and Compact I/O systems in panels fed from 230V AC: pump station controllers in water and wastewater networks, packaging and bottling machines, HVAC and chiller plant controls, and skid-mounted process units in oil and gas facilities. Its wide 85–265V AC input range covers the local 230V/50 Hz supply and also equipment built for 120V markets.

Why Source from Seven Star LLC

Seven Star LLC is an independent supplier in Muscat. Seven Star LLC supplies Allen-Bradley Compact I/O power supplies and related automation hardware across Oman and the GCC. Send the 1769-PA4 catalog number, the quantity and your bank module list and request a quote; our team can help confirm the correct ordering code.