Allen Bradley 1756-PA50 ControlLogix Standard Power Supply

The Allen Bradley 1756-PA50, also cataloged as the 1756-PA50 Standard DC Power Supply, operates as a dedicated hardware component for chassis power distribution within ControlLogix system platforms. This module provides direct physical/electrical execution by converting 85-265 VAC input voltage into regulated DC outputs required by the chassis backplane to support processor, communication, and I/O module operation.

Hardware Specifications

ControlLogix Deterministic Network Integration

The 1756-PA50 is engineered to maintain stable power delivery across the ControlLogix backplane, ensuring consistent backplane bus communication velocity for high-speed I/O and processor modules. The power supply's output regulation characteristics are critical for maintaining the deterministic performance of Profinet / EtherNet/IP deterministic networks, especially during transient load conditions caused by module I/O density scaling. Firmware flash compatibility and diagnostic status reporting through the chassis backplane allow for proactive monitoring of power rail health and remaining hold-up time during AC line voltage fluctuations.

Frequently Asked Questions (FAQ)

Q: Can the 1756-PA50 be mounted on the right side of the ControlLogix chassis?

A: No. The 1756-PA50 is physically keyed and electronically mapped for installation only on the left side of the ControlLogix chassis.

Q: What is the hold-up time during an input voltage loss?

A: The hold-up time is dependent on the load; the unit provides 30 ms at 60 W load or 40 ms at 50 W load when supplied within the specified input range.

Field Installation Guidelines

• Mounting Orientation: The module must be inserted into the left-most slot of the ControlLogix chassis. Ensure the module is fully seated and the mechanical latch is secured to guarantee proper backplane pin engagement.
• Cooling and Ventilation: Maintain a minimum clearance of 50 mm above and below the power supply to ensure proper thermal dissipation. Do not obstruct the integrated fan or airflow vents, as derating occurs when operating at the 60 deg C temperature limit.
• AC Input Wiring: Use 14-22 AWG copper wire for AC input connections. Ensure the input wiring is routed separately from backplane signal cables to prevent AC noise injection into the chassis logic circuits.
• Grounding: Connect the chassis ground terminal to a common earth ground. This reduces potential differences and provides a low-impedance path for surge voltage protection, safeguarding the module against power line transients.