Product Overview

The Allen-Bradley 1756-PB72 is a high-capacity DC input power supply engineered to provide regulated voltages to the backplane of a ControlLogix® chassis. This module is essential for converting a nominal 24V DC source into the specific logic-level voltages required by the processor and I/O modules. Designed for high-reliability industrial automation, the 1756-PB72 mounts directly to the left side of a 1756-A4, A7, A10, A13, or A17 chassis, ensuring it does not occupy a functional module slot while providing robust electrical distribution.

The unit is built with reinforced insulation and has undergone rigorous dielectric testing at 3,500V DC to ensure maximum operator and equipment safety. It is specifically optimized for environments where AC power is unavailable or where a battery-backed DC bus is utilized for increased system availability. With its significant current sourcing capabilities across three voltage rails, it can support high-density chassis configurations without the risk of thermal throttling or voltage sag.

Electrical Performance and Environmental Resilience

The 1756-PB72 excels in maintaining steady power delivery despite industrial electrical interference. It features advanced surge transient immunity of ±1 kV line-to-line and ±2 kV line-to-earth, shielding sensitive backplane electronics from field-side voltage spikes. The module's internal circuitry is designed for high efficiency, minimizing heat dissipation to ensure a long service life within enclosed control cabinets.

Operationally, the module is resilient against mechanical stress, featuring vibration resistance of 2 G at frequencies up to 500 Hz. This makes it suitable for installation on machinery subject to constant motion or in heavy manufacturing zones. A clear green LED on the front panel provides immediate visual confirmation that the input voltage is within the functional range and the backplane is receiving power.

Technical Specifications

• Manufacturer: Allen-Bradley (Rockwell Automation)

• Model Number: 1756-PB72

• Input Voltage: 24V DC (Range: 18-32V DC)

• Backplane Output Current: * 4 A @ 3.3V DC

• 10 A @ 5.1V DC

• 2.8 A @ 24V DC

• Power Dissipation: 25 Watts

• Inrush Current: 30 A Maximum

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

• Chassis Compatibility: ControlLogix 1756 Series A, B, and C

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

• Dimensions: 14.0 x 11.2 x 14.5 cm

• Weight: 0.98 kg

Core Features and Installation

• Non-Slot Occupying Design: Mounts directly to the chassis frame, preserving all available slots for I/O and communication modules.

• User-Friendly Wiring: Input terminals are protected by a hinged cover door with clear DC+ and DC- markings for error-free installation.

• Diagnostic LED: Features a "Power OK" indicator for rapid visual troubleshooting.

• Enhanced Safety: Built-in overcurrent and overvoltage protection safeguards the entire chassis backplane.