Product Overview
The Allen-Bradley 1756-PB75R is a ControlLogix redundant power supply module designed to ensure continuous operation of your automation system. When paired with a second unit, it forms a hot-standby assembly: one unit actively powers the chassis while the other stands by, automatically taking over if a fault occurs. This architecture directly reduces the risk of unplanned downtime caused by power supply failure.
Part of the Rockwell Automation ControlLogix family, the 1756-PB75R accepts a 24V DC nominal input (range 19–32V DC) and delivers 75W of output power across the operating temperature range of 0–60°C (32–140°F). With built-in status indicators and automatic chassis load sharing, this module simplifies diagnostics and balances power draw across redundant supplies.
Technical Specifications
Key parameters of the 1756-PB75R are listed below. All values are from the manufacturer's data.
| Parameter |
Value |
| Input Voltage Range |
18–32V DC (nominal 24V DC) |
| Output Power |
75W @ 0–60°C (32–140°F) |
| Current Capacity @ 1.2V |
1.5A |
| Current Capacity @ 3.3V |
4A |
| Current Capacity @ 5.1V |
13A |
| Current Capacity @ 24V |
2.8A |
| Inrush Current (max) |
30A |
| Input Power (max) |
110W |
| Operating Temperature |
0–60°C (32–140°F) |
| Nonoperating Temperature |
-40–85°C (-40–185°F) |
| Relative Humidity (operating) |
5–95% noncondensing |
| Vibration (operating) |
2G @ 10–500 Hz |
| Shock (operating / nonoperating) |
30G / 50G |
| Dimensions (approx.) |
140 x 112 x 145 mm (5.51 x 4.41 x 5.71 in.) |
| Weight (approx.) |
0.95 kg (2.10 lb) |
| Compatible Chassis |
1756-A4, 1756-A7, 1756-A10, 1756-A13, 1756-A17 |
Industry Applications
The 1756-PB75R is ideal for mission-critical processes where power continuity is non-negotiable. Typical applications include:
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Manufacturing lines – Keep PLCs running through brief power interruptions, preventing line stops and product loss.
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Process control – In chemical or oil & gas plants, redundant power minimizes the chance of a controller shutdown that could trigger safety interlocks.
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Utilities and infrastructure – Water treatment, power distribution, and building automation systems benefit from hot-standby capability.
By implementing a redundant pair, operators can perform maintenance or replacement of one supply without shutting down the entire control system.
Installation & Setup Guidance
Mount the 1756-PB75R in a compatible 1756 chassis (A4, A7, A10, A13, A17). Ensure the chassis is properly grounded and that input wiring uses 2.5 mm² (14 AWG) copper wire with insulation rated for at least 90°C (194°F). The module’s input connections are auto-sensing, so no manual voltage selection is required.
For redundant operation, connect the two power supplies using the 1756-CPR2 cable to the 1756-PSCA2 chassis adapter. Important: Always disconnect power before connecting or disconnecting this cable to avoid electrical arcing, which can be hazardous in explosive environments.
After installation, verify the status indicator shows proper operation. The module supports hot-swap replacement in nonredundant mode, meaning you can replace a faulty unit while the system remains powered.
Maintenance & Reliability
Regular inspection of the 1756-PB75R ensures long-term reliability. Check for dust accumulation on the enclosure and ensure airflow is not blocked. Operate within the specified temperature and humidity ranges; the module is rated for 0–60°C and 5–95% noncondensing humidity. Vibration and shock limits are 2G at 10–500 Hz and 30G operating shock, respectively. Avoid exposing the unit to conditions beyond these limits.
Because the redundant design automatically transfers load, you can inspect or replace one unit without interrupting the process. This reduces maintenance downtime and extends overall system availability.
Compatibility & Integration
The 1756-PB75R is designed for the ControlLogix platform and fits in the 1756-A4, 1756-A7, 1756-A10, 1756-A13, and 1756-A17 chassis. It works with any ControlLogix controller and communicates over the backplane to provide power to all modules. No additional communication protocols are required for operation.
Selection Guide & Purchasing Advice
Before ordering, verify your chassis model and confirm that your system requires redundant power. If you are upgrading an existing single-supply setup, ensure the chassis has an available slot for the second unit. The 1756-PB75R is a genuine Rockwell Automation part, ensuring full compatibility and performance.
When sourcing this module, choose a trusted supplier like PLC Source PRO to guarantee authentic parts and reliable delivery. We stock a wide range of ControlLogix spares and accessories.