Why the 1756-PH75 Belongs on Your Spares List
When a ControlLogix chassis loses its power supply, the whole line stops. The Allen-Bradley 1756-PH75 is the standard DC power module that keeps Series B chassis alive in oil, gas, and heavy industrial automation cabinets. It takes a 125V DC nominal feed and delivers the regulated rails your 1756 modules need.
This is not a generic supply. It is built for the 1756-A4, 1756-A7, 1756-A10, 1756-A13, and 1756-A17 chassis, mounting in the left slot where the backplane expects it.
What the 1756-PH75 Actually Delivers
The input stage accepts 90-143V DC and draws up to 95W. From that it produces 75W of output power at 60 degrees Celsius, with a 30A current surge to ride through startup. The load-dependent current capacity is the part engineers check first:
- 1.5A at 1.2V
- 4A at 3.3V
- 13A at 5.1V
- 2.8A at 24V DC
That 13A at 5.1V rail is the workhorse. It feeds the chassis backplane, so every I/O and communication module in the rack depends on it. Isolation between input and backplane is rated 250V, with reinforced insulation type-tested at 3500V DC for 60 seconds.
Built for Harsh Cabinets
The 1756-PH75 operates from 0 to 60 degrees Celsius and is tested to IEC 60068-2-30 at 5-95% non-condensing relative humidity. It withstands 30G operational shock and 2G vibration, with 50G in non-operating mode. Storage range is -40 to 85 degrees Celsius. The module has no enclosure, so it relies on the chassis and cabinet for protection.
Weighing 2.10 pounds and measuring 5.51 x 4.41 x 5.71 inches, it is a compact drop-in for the left slot. Wiring uses 2.5mm2 stranded or solid copper with 1.2mm insulation rated at 90 degrees Celsius, torqued to 0.8 N-m (7 lb-in).
Where It Fits in Your Operation
In upstream oil and gas, this supply often sits in a control room cabinet running pump and valve logic. The wide 90-143V DC range means it tolerates the voltage sag common on DC battery-backed systems. In a plant retrofit, the 1756-PH75 is the practical replacement when a legacy DC supply drifts out of tolerance and starts dropping modules offline.
Because the module is a direct fit for Series B chassis, you avoid rewiring the backplane. That keeps downtime short and gets the line back faster.
Before You Order
Confirm three things: your chassis is a Series B 1756 unit, your DC feed falls inside 90-143V DC, and your total module load stays within the current limits above. If you are unsure, our team can help you match the supply to your rack configuration.
Please verify current lifecycle status and availability with Oil AutoTech before ordering. We keep fast-dispatch spares for oil, gas, and industrial automation, with quick worldwide delivery and hands-on technical selection help.
