Allen-Bradley 1746-P3 SLC 500 24V DC Power Supply Module

Description

Key Technical Specifications

Product Introduction & Supply Chain Strategy

This product is a Brand New Surplus unit. It is not used, not pulled from a decommissioned plant, and not refurbished. All modules undergo rigorous quality verification to ensure OEM-level reliability. The Allen-Bradley 1746-P3 is a 24 V DC input power supply designed to seat directly into the left side of any standard 1746 chassis, delivering regulated 5 V DC and 24 V DC power across the backplane to drive SLC 500 CPU and I/O modules in industrial process lines, marine systems, and isolated remote terminal units (RTUs).

Because Rockwell Automation has transitioned the SLC 500 series to active-discontinued status, sourcing the 1746-P3 as New Surplus is a critical risk mitigation strategy for your facility’s Total Cost of Ownership (TCO). Relying on refurbished power supplies introduces degraded capacitors that increase backplane ripple voltage and risk cascading failures across your controller cards. Securing factory-fresh surplus units guarantees a 10-15 year operating lifespan and provides essential buffer stock, protecting your operation against severe loss of production during an emergency power bus fault.

1746-P3

1746-P3

1746-P3

Installation & Configuration Guide

1.Stage 1: Pre-Installation (Prep & Safety):Mitigate electrical hazards and document wiring before servicing.

• Execute full Lock-Out/Tag-Out (LOTO) procedures on the incoming 24 V DC power feed supplying the power module.
• Wear a properly grounded Electrostatic Discharge (ESD) wrist strap connected to unpainted chassis ground.
• Take clear photos of terminal strip wiring (+24V, DC GND, Chassis GND) and verify wire label markers match system schematics.

2.Stage 2: Removal:Safely disengage the failed power module from the chassis.

• Disconnect the wiring harness from the 1746-P3 barrier terminal block.
• Loosen the upper and lower mounting screws that secure the power supply unit to the left end of the 1746 chassis frame.
• Slide the power supply straight out toward you, ensuring you pull horizontally to prevent twisting and bending the chassis backplane connectors.

3.Stage 3: Installation (Clone & Seat):Position and secure the new surplus unit.

• Inspect the backplane edge connectors on the 1746-P3 for dust or packaging debris.
• Align the module with the card guides on the far-left slot of the 1746 rack.
• Slide the unit firmly back until the connectors fully mate with the backplane bus, then tighten the upper and lower mounting screws to ensure proper grounding.
• Re-attach input wiring to the terminal block following your previously documented pinout configuration.

4.Stage 4: Power-On & Testing:Validate voltage stability before placing the PLC in RUN mode.

• Use a calibrated digital multimeter (DMM) to check the incoming DC power lines for shorts or out-of-spec voltage (must measure 10-30 V DC).
• Energize the 24 V DC supply feed to the module.
• Verify that the green POWER LED on the front faceplate illuminates solid green.
• Monitor the CPU module status LEDs; ensure no system backplane faults occur during initialization.

Firmware/Software Versions & Upgrade Notes

• Hardware Hardware Revision Compatibility: The 1746-P3 is a hardware power module and operates independently of PLC firmware revisions. It supports all SLC 5/01, 5/02, 5/03, 5/04, and 5/05 processors installed in standard 1746 rack layouts.
• Series Compatibility: Compatible with Series A, B, and C 1746 chassis systems. No software driver or RSLogix 500 hardware configuration changes are required when replacing a unit like-for-like.
• Firmware Risks During Hardware Swaps: While the power supply requires no firmware updates, unexpected power cycles caused by unstable power rails during a swap can corrupt RAM on older SLC CPUs if the memory retention battery is depleted. Always upload and backup the PLC program logic before replacing hardware on aging legacy racks.

Frequently Asked Questions (FAQ)

Why is this New Surplus unit priced lower than OEM list but higher than refurbished options?

Our pricing reflects the true market value of obtaining verified, un-used OEM inventory from global strategic reserves. Refurbished components are priced low because they carry worn capacitors and aged power transformers. New Surplus gives you 100% factory reliability and full service life without the inflated markup of legacy OEM list prices.

Are these 1746-P3 power supplies genuinely new?

Yes. Every unit is original Allen-Bradley stock, sourced from cancelled capital projects and redundant plant reserves. They feature clean backplane pins, zero solder fatigue, and original packaging. Packaging is opened only by our certified technicians inside ESD-safe environments to perform visual and electrical testing before shipment.

Can I hot-swap the 1746-P3 power supply while the SLC 500 rack is powered?

No. The SLC 500 chassis design does not support hot-swapping. Attempting to pull or insert a power supply unit while input power is applied will cause electrical arcing, potentially damaging the backplane, CPU, and adjacent I/O modules. Always isolate input power prior to removal.

Does the 1746-P3 supply 24 V DC user power to external field sensors?

No. Unlike the AC-input models (such as the 1746-P1 or 1746-P2), the 1746-P3 uses all incoming power to generate the internal 5 V DC (3.6 A) and 24 V DC (0.8 A) rails required solely by the backplane cards. External field devices require a separate dedicated 24 V DC power supply.

What warranty coverage comes with this New Surplus unit?

We provide a comprehensive 1-Year warranty (depending on your service agreement level) covering full module replacement. If the unit experiences any hardware malfunction during normal operating conditions, we replace it immediately from our dedicated emergency inventory.