Product Overview

The Allen-Bradley 1756-PA75 is a high-capacity AC power supply module engineered to provide the primary DC power requirements for the ControlLogix® 1756 chassis. This 75-watt unit is an essential infrastructure component, converting industrial-grade AC line power into the multiple regulated DC voltage levels (1.2V, 3.3V, 5.1V, and 24V DC) required by processors, communication adapters, and I/O modules via the backplane. Designed for high-availability systems, the 1756-PA75 ensures that sensitive logic electronics receive a clean, stabilized energy source even in electrically noisy factory environments.

This module mounts directly to the dedicated power supply footprint on the far-left side of any standard ControlLogix chassis. Its wide-range input capability allows for universal deployment, supporting diverse global power standards without the need for external step-down transformers or manual voltage switching.

Performance and Reliability Features

The 1756-PA75 is built with advanced circuit protection and thermal management to ensure continuous system uptime.

• Universal Input Range: Effectively operates with input voltages ranging from 85V to 265V AC, accommodating both 120V and 240V nominal systems across 47–63 Hz frequencies.

• Holdup Time Capability: Features integrated energy storage to provide a specified ride-through time (holdup time), allowing the PLC system to maintain operation during brief voltage dips or power interruptions.

• Safety Isolation: Engineered with reinforced insulation and electrical separation to protect the low-voltage backplane components from high-voltage line surges and transients.

• Overcurrent Protection: Includes internal non-replaceable fusing and current-limiting circuitry to prevent system damage in the event of a downstream short circuit or power surge.

• Visual Diagnostics: Front-panel LED indicators provide immediate status verification of input power health and DC output stability, simplifying cabinet-level troubleshooting.

Technical Specifications

• Manufacturer: Allen-Bradley (Rockwell Automation)

• Model Number: 1756-PA75

• Module Type: AC Power Supply

• Input Voltage: 85V–265V AC (Universal)

• Output Power: 75 Watts @ 60°C

• Backplane Current (Max): 13A @ 5.1V DC; 2.8A @ 3.3V DC; 1.5A @ 24V DC

• Frequency Range: 47–63 Hz

• Isolation Voltage: 250V (continuous), Reinforced Insulation Type

• Operating Temperature: 0°C to 60°C (32°F to 140°F)

• Dimensions: 14.5 x 3.5 x 13.0 cm

• Weight: 0.9 kg (1.98 lbs)

Installation and System Maintenance

The 1756-PA75 is designed for tool-free installation onto the 1756 chassis frame. It connects to the backplane through a high-durability connector designed for long-term service life.

• Chassis Compatibility: Compatible with all standard 1756-A4, A7, A10, A13, and A17 ControlLogix racks.

• Cooling Requirements: Utilizes natural convection cooling; proper clearance must be maintained around the chassis to ensure the module operates within its specified thermal envelope.

• Environmental Rating: Suitable for use in Pollution Degree 2 industrial environments and carries global certifications including UL, CSA, CE, and Ex-ratings for hazardous area suitability.