Purchase now: Allen-Bradley 1756-PA72 ControlLogix AC Power Supply
Atlantechdrives provides you the 1756-PA72, a versatile and robust AC power supply designed specifically for the ControlLogix 1756 chassis system. This module is the standard energy backbone for medium to large-scale automation racks, providing the necessary DC voltages to the backplane to power processors, I/O modules, and communication bridges.
- Input Voltage: 85-265V AC (47-63 Hz)
- Output Current (Backplane): 10A @ 1.2V, 4A @ 3.3V, 13A @ 5.1V, 2.8A @ 24V
- Power Consumption: 100 Watts max
- Mounting: Left side of the 1756 chassis
- Isolation Voltage: 250V continuous
Technical Performance: Power Integrity for ControlLogix
The 1756-PA72 is engineered to provide stable, filtered power even in unstable industrial electrical environments. It features an integrated surge suppression system that protects the sensitive electronics in the backplane from voltage spikes and line noise. With its wide input voltage range (85-265V AC), it can be deployed globally without the need for additional step-down transformers in most industrial regions. The 1756-PA72 provides four different voltage rails to the backplane simultaneously, ensuring that legacy modules (5V) and modern high-speed processors (1.2V/3.3V) all receive the precise potential they require for deterministic operation.
Installation Advice: Chassis Grounding and Heat Dissipation
When installing the 1756-PA72, the quality of your chassis ground connection is the most important factor for long-term reliability. Use a heavy-gauge copper wire to connect the chassis ground stud to your main enclosure’s ground bus bar. This helps the internal surge suppressors shunt transient energy away from the backplane. Additionally, ensure that there is at least 2 inches (5 cm) of clear space above and below the chassis. The 1756-PA72 is a switching power supply and generates heat; obstructing the ventilation slots can lead to thermal shutdown or a shortened lifecycle of the internal electrolytic capacitors.
Maintenance and Troubleshooting Power Faults
The 1756-PA72 features a front-panel green LED that indicates the status of the output voltages. If this LED is OFF, the first step is to check the internal fuse. Note that the internal fuse is typically not user-replaceable; if it blows, it often indicates a catastrophic internal component failure or a dead short on the backplane. We recommend an annual visual inspection for any signs of discoloration around the power terminals. To prevent unplanned downtime, monitor the «Power Supply Health» tags in Studio 5000 (if using redundant setups) or use an external power monitor to detect frequent brownouts that could stress the supply’s input stage.
FAQs
Q: Can I use the 1756-PA72 in a redundant power configuration?
A: No, the 1756-PA72 is a standard supply. For redundancy, you would need a 1756-PA75R and a redundancy module.
Q: What is the difference between PA72 and PA75?
A: The PA75 provides higher output current (13A vs 10A at certain rails) and is intended for larger, high-density racks.
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