Allen-Bradley 1746-P2 Power Supply — Comprehensive Product Introduction

Introduction

In a programmable logic controller (PLC) system, the power supply is the first and most fundamental component in the chain of reliability. Without a stable and robust power source, even the most advanced controller cannot operate. The Allen-Bradley 1746-P2 is a standard power supply designed for the SLC 500 series of controllers by Rockwell Automation. As part of the SLC 500 modular family, this power supply is critical for energizing the backplane and all modules in the chassis, ensuring that the control system remains operational under a wide variety of conditions.

The 1746-P2 is known for its dependable performance in demanding industrial environments, offering a balance of capacity, efficiency, and durability. It provides regulated power to SLC processors, input/output modules, communication adapters, and specialty modules, all of which rely on clean, consistent DC voltage for proper function.

Unlike batteries or interface converters, which serve auxiliary functions, the 1746-P2 is a primary system component — its continuous operation is mandatory for keeping the controller online. A well-chosen and well-maintained power supply can extend the life of the entire PLC system and prevent costly unplanned shutdowns.

The Role of the 1746-P2 in Control Systems

The SLC 500 platform is modular, meaning that users can select the exact number and types of modules they need for a given application. All of these modules plug into a common chassis, and the 1746-P2 provides the electrical power that feeds the backplane. The backplane distributes this power to each module in the chassis.

The 1746-P2 is designed to be installed in the leftmost slot of the chassis, which is reserved for the power supply. Once installed, the power supply converts incoming AC voltage to the regulated DC power required by the system. It is engineered to handle a mix of digital, analog, and specialty modules without voltage sag, even under full load.

In addition to providing power, the 1746-P2 helps protect the system from line disturbances such as surges and transients, providing a degree of electrical isolation from the plant’s AC mains.

Key Features

Some of the most important features of the Allen-Bradley 1746-P2 include:

• Wide Input Voltage Range: Accepts 85 to 264 VAC, making it suitable for installation in facilities with varying power standards.

• Automatic Switching: Can accommodate different AC line voltages without requiring manual selector switches or jumpers.

• Sufficient Output Capacity: Provides enough current for a wide variety of I/O and specialty module combinations.

• High Reliability: Designed to operate continuously in harsh industrial conditions, with MTBF (mean time between failures) measured in decades.

• Compact Form Factor: Occupies only the left slot in the chassis, allowing full use of the remaining slots for control modules.

• Integrated Protection: Includes internal fusing and current limiting to safeguard against overload conditions.

Technical Specifications

The following table summarizes the key technical specifications of the Allen-Bradley 1746-P2 power supply:

This specification table is particularly valuable for system designers who must ensure that their power supply can handle the load requirements of the selected module configuration.

Installation and Setup

Installing the 1746-P2 is straightforward but should follow best practices:

1. Chassis Preparation: Ensure that the chosen chassis is securely mounted and that the leftmost slot is reserved for the power supply.

2. Electrical Connection: Connect the incoming AC mains wiring to the terminal block on the power supply. Follow proper grounding procedures and verify correct polarity.

3. Load Consideration: Before applying power, verify that the total current consumption of the installed modules does not exceed the current capacity of the power supply.

4. Power Up: Once installed, apply AC power and check that the power supply LED indicator is lit, confirming proper operation.

Correct installation minimizes the risk of electrical faults and ensures optimal system performance.

Application Scenarios

The 1746-P2 is widely used in applications that range from small machine controls to plant-wide distributed systems. Examples include:

• Discrete Manufacturing: Assembly machines, conveyors, and packaging systems that require reliable power to run multiple I/O modules.

• Process Control: Batch or continuous processes that depend on uninterrupted controller operation.

• Infrastructure Automation: Water treatment, pumping stations, and building management systems that require long-term reliability.

• Training and Simulation: Educational labs that use SLC 500 hardware to teach PLC programming and system design.

Because the SLC 500 family is still in use in many facilities worldwide, the 1746-P2 remains a highly relevant and practical choice.

Advantages and Benefits

Using the 1746-P2 power supply brings several key benefits:

• Stability: Provides regulated voltage, protecting sensitive electronics from power fluctuations.

• Flexibility: Wide input voltage range allows deployment in multiple regions without modification.

• Simplicity: Easy to install and maintain, reducing commissioning time.

• Longevity: Supports legacy SLC systems, allowing facilities to extend the life of their installed base.

• Cost-Effectiveness: Avoids premature system upgrades by keeping existing hardware powered and functional.

Maintenance and Reliability

Although the 1746-P2 is designed for many years of service, it should still be included in a preventive maintenance schedule. Recommendations include:

• Visual Inspection: Check periodically for loose wiring, signs of overheating, or physical damage.

• Load Verification: Ensure that added modules do not exceed the power supply’s current rating.

• Spare Parts Strategy: Keep at least one spare power supply available for critical systems to minimize downtime during unexpected failures.

Because it uses passive cooling and has no moving parts, the 1746-P2 typically operates for many years without intervention.

Safety and Compliance

The 1746-P2 meets relevant global safety and electromagnetic compatibility standards, ensuring that it can be installed in industrial control panels worldwide. Proper grounding and adherence to local electrical codes are essential to ensure operator safety and system reliability.

Conclusion

The Allen-Bradley 1746-P2 power supply is a cornerstone component of the SLC 500 PLC platform, delivering reliable power to every module in the chassis. With its wide input voltage range, compact design, and proven dependability, it is an ideal solution for both new installations and existing systems that continue to rely on the SLC architecture.

By properly sizing, installing, and maintaining the 1746-P2, automation engineers can ensure stable system operation, minimize downtime, and maximize return on investment. Whether in manufacturing, utilities, or infrastructure control, this power supply continues to serve as a trusted backbone for critical automation applications.