Allen-Bradley 1756-PA75/B ControlLogix Power Supply | Replacement, Equivalent & Selection Guide
The Allen-Bradley 1756-PA75/B is a high-performance AC input power supply designed for the ControlLogix 1756 chassis platform. As a Series B unit, it delivers enhanced reliability and thermal management over its predecessor. This page provides full technical specifications, compatible replacement models, application guidance, and sourcing information to help engineers and procurement teams make confident decisions.
Technical Specifications
- Catalog Number: 1756-PA75/B
- Series: B
- Manufacturer: Allen-Bradley / Rockwell Automation
- Input Voltage: 85–265 VAC, 47–63 Hz (wide-range AC)
- Output Power: 75 W total (backplane)
- Output Voltage: 1.2 V, 3.3 V, 5 V, 24 VDC backplane rails
- Chassis Compatibility: All 1756 ControlLogix chassis (4, 7, 10, 13, 17-slot)
- Operating Temperature: 0–60 °C
- Certifications: UL, CE, cUL
- Form Factor: Single-slot, left-side chassis mount
- Dimensions (H × W × D): 144.8 × 44.5 × 130.8 mm (approx.)
- Weight: ~1.0 kg
- Part Status: Active / Orderable
Compatible Replacement & Equivalent Models
The following models are functionally compatible or serve as direct/near-direct replacements for the 1756-PA75/B in most ControlLogix applications. Always verify chassis slot count and load requirements before substituting.
- 1756-PA75/C — Series C successor; drop-in replacement with identical electrical specs and improved firmware support.
- 1756-PA72 — Lower-wattage (72 W) AC supply; suitable for lighter chassis loads (≤10 modules).
- 1756-PB75/B — DC input equivalent (18–32 VDC); use when AC mains are unavailable.
- 1756-PB72 — DC input, 72 W; compatible with 24 VDC plant power systems.
- 1756-PA16 — Redundant power supply option; pair with 1756-PSCA2 for hot-standby configurations.
- 1756-PA75R — Redundant-capable variant; recommended for high-availability architectures.
Note: Third-party compatible supplies are available. Contact us to confirm interoperability with your specific chassis revision and firmware version.
Why Choose the Original Model
- Guaranteed Interoperability: Factory-validated with all 1756 chassis revisions and ControlLogix firmware versions.
- Rockwell Warranty & Support: Eligible for Rockwell Automation TechConnect support contracts.
- Series B Improvements: Enhanced EMI filtering, improved thermal derating curve, and updated capacitor specification vs. Series A.
- Long Service Life: Designed for 24/7 industrial duty cycles in harsh environments.
- Traceability: Full OEM traceability for regulated industries (pharma, food & beverage, oil & gas).
Typical Applications
- Discrete manufacturing automation (automotive, assembly lines)
- Process control systems (chemical, refining, water treatment)
- Material handling and conveyor control
- Building automation and HVAC control panels
- Oil & gas upstream/downstream control cabinets
- Pharmaceutical batch processing (21 CFR Part 11 environments)
- Power generation and utilities SCADA integration
System Compatibility
- PLC Platform: Rockwell Automation ControlLogix 1756 series
- Compatible Chassis: 1756-A4, 1756-A7, 1756-A10, 1756-A13, 1756-A17
- Compatible Controllers: 1756-L6x, 1756-L7x, 1756-L8x series (all ControlLogix CPUs)
- Communication Modules: Compatible with all 1756 EtherNet/IP, ControlNet, DeviceNet, and PROFIBUS modules
- Redundancy: Supports 1756-SRM (System Redundancy Module) configurations when paired with 1756-PA75R or 1756-PA16
- Software: Studio 5000 Logix Designer v21 and above; RSLogix 5000 v16+
Selection Guide
Use the following criteria to select the correct power supply for your ControlLogix system:
- Step 1 — Calculate chassis load: Sum the backplane current draw of all installed I/O, communication, and controller modules. The 1756-PA75/B supports up to 75 W total backplane output.
- Step 2 — Confirm input power source: AC mains (85–265 VAC) → use 1756-PA75/B. DC plant power (18–32 VDC) → use 1756-PB75/B.
- Step 3 — Assess redundancy requirements: For SIL-rated or high-availability systems, select 1756-PA75R with 1756-PSCA2 redundancy chassis adapter.
- Step 4 — Verify chassis slot: The power supply occupies the leftmost slot; confirm chassis revision accepts Series B supply.
- Step 5 — Check ambient temperature: Derate output above 40 °C per Rockwell publication 1756-TD001. At 60 °C, available output is reduced — recalculate load margin.
Quality Assurance & Sourcing
- Authenticity: All units sourced from authorized distributors or directly from Rockwell Automation-certified channels.
- Inspection: Each unit undergoes visual inspection, label verification, and functional power-on test prior to shipment.
- Condition: New (factory-sealed), Refurbished (tested to OEM spec), and Surplus (unused, original packaging) options available — specify at time of order.
- Documentation: Certificate of Conformance (CoC) and test reports available on request.
- Anti-Counterfeit: We verify holographic labels, date codes, and PCB markings against Rockwell Automation reference standards.
- Warranty: 12-month warranty on all units; extended warranty available.
How to Order
- Catalog Number: 1756-PA75/B
- Specify: Quantity, required condition (New / Refurbished / Surplus), and delivery timeline.
- Request a Quote: Email [email protected] or call +0086 19859288691.
- Lead Time: In-stock units ship within 1–3 business days; special orders quoted individually.
- Payment: T/T (wire transfer), PayPal, and trade credit terms available for qualified accounts.
- Export: We ship worldwide with full export documentation (commercial invoice, packing list, COO).
Replacement & Compatibility FAQ
Q: Can I replace a 1756-PA75/B (Series B) with a Series C unit?
A: Yes. The 1756-PA75/C is a direct drop-in replacement with identical mounting, electrical interface, and backplane connector. No firmware changes are required.
Q: Is the 1756-PA75/B compatible with the 1756-A17 (17-slot) chassis?
A: Yes, provided the total module backplane load does not exceed 75 W. Calculate your load using Rockwell publication 1756-TD001 before populating a full 17-slot chassis.
Q: Can I use a 1756-PB75/B (DC input) as a replacement?
A: Only if your panel provides 18–32 VDC input power. The PB variant is electrically equivalent on the backplane output side but requires a DC source — it is not interchangeable from an input wiring perspective.
Q: What happens if the power supply is undersized?
A: The supply will enter thermal shutdown or trigger the chassis fault LED. Always maintain ≥20% load margin for reliable operation.
Q: Do you supply test reports for refurbished units?
A: Yes. Full functional test reports and CoC documents are available upon request for all refurbished inventory.
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