Allen-Bradley 1746-P1 SLC 500 Power Supply Module

1746-P1 Power Supply by Allen-Bradley for SLC 500

Product Introduction

The Allen-Bradley 1746-P1 is an essential component for any SLC 500 control system. As the primary power source, this module supplies the backplane with the necessary DC voltage to operate all connected I/O and processor modules.

This power supply accepts a broad input voltage range from 85 to 265 VAC at 47–63 Hz, making it suitable for various global industrial sites. It delivers an internal current capacity of 2 A at 5 VDC and 0.46 A at 24 VDC to the backplane. Additionally, it offers a user-power output of 24 VDC with a capacity of 200 mA, which is ideal for powering field sensors or other low-energy devices.

One of the key features of the 1746-P1 is its built-in fuse protection (user-replaceable with the 1746-F1 kit). This safeguard protects against fire hazards due to short-circuit conditions. Furthermore, the module provides galvanic isolation of 1800 Volts AC RMS between the input terminals and the backplane, enhancing system safety and noise immunity.

Technical Specifications

The 1746-P1 power supply is engineered for consistent performance under demanding conditions. Its technical highlights are detailed below:

• Input Voltage: 85 to 132 VAC or 170 to 265 VAC (auto-selection via jumper)

• Input Frequency: 47 to 63 Hz

• Input Power: 42 Watts (typical) / 135 VA

• Inrush Current: 20 Amps (maximum)

• Internal Current Capacity: 2 A at 5 VDC and 0.46 A at 24 VDC

• User-Power Output: 24 VDC at 200 mA (voltage range: 18 to 30 VDC)

• Backplane Current: 2 A (5V) and 0.46 A (24V)

• Isolation: 1800 Volts AC RMS for 1 second

• Fuse Protection: Uses 1746-F1 or an equivalent replacement

This module is designed to fit exclusively into the leftmost slot of a 1746 chassis. Only one power supply is required per rack, whether it is a main, expansion, or remote I/O rack.

Mechanical and Environmental Parameters

The mechanical design of the SLC 500 power supply ensures durability and easy integration. Its compact dimensions and lightweight construction simplify installation.

• Dimensions (H x W x D): 5.5 x 2.3 x 5.7 inches (140 x 58 x 145 mm)

• Weight: 2.0 pounds (0.9 kilograms)

• Operating Temperature: 0 to 60 °C

• Derating: Current capacity is derated by 5% when the ambient temperature exceeds 55 °C.

Installation Guidelines

Proper installation is critical for the safe and reliable operation of the 1746-P1. Follow these steps to ensure correct setup:

1. Set the Input Jumper: Before applying power, verify that the input voltage selector jumper matches your supply voltage (120V or 220V). Exposed pins carry hazardous voltage when power is applied.

2. Mount in the Chassis: Install the module in the leftmost slot of the SLC 500 chassis. Secure it using the chassis mounting screws.

3. Connect Power Wiring: Attach the line, neutral, and ground wires to the designated terminals on the front of the module.

4. Verify Overcurrent Protection: For the user-power circuit, ensure your external protection does not exceed 15 A.

Additionally, the 1746-P1 supports a CPU hold-up time of 20 ms at full load and 3000 ms at no load. This feature allows the processor to continue scanning during brief power sags. If undervoltage persists beyond the hold-up time, the module stops supplying power but automatically resumes normal operation when voltage returns.

Packaging List

Your shipment includes the following items:

• (1) Allen-Bradley 1746-P1 Power Supply Module

• (1) User manual and installation guide (digital copy)

• (1) Input voltage selection jumper (pre-installed)

Frequently Asked Questions (FAQ)

1. Can I replace the internal fuse myself?
Yes, the internal fuse is user-replaceable. Use the Allen-Bradley 1746-F1 fuse kit or an equivalent replacement. Always disconnect power before servicing.

2. What happens during an overcurrent condition on the user-power output?
For Series A units made in Japan, a power supply shutdown occurs, and you must reload the user program. For Series A units made in Malaysia, the 24 VDC user-power shuts down, but the CPU continues to run; simply correct the overcurrent condition to restore operation.

3. How many power supplies can I install in one chassis?
Only one 1746-P1 is needed and supported per SLC 500 chassis. It is installed in the leftmost slot.

4. What is the CPU hold-up time for this module?
The 1746-P1 provides a hold-up time of 20 milliseconds at full load and up to 3000 milliseconds at no load, allowing the processor to ride through brief input voltage dips.

5. Is this module compatible with all SLC 500 racks?
Yes, the 1746-P1 power supply is fully compatible with standard 1746 chassis, including main, expansion, and remote I/O racks.