Allen-Bradley 1746-P4 SLC 500 Power Supply

Allen-Bradley 1746-P4 SLC 500 Power Supply

Product Introduction

The 1746-P4 is an essential component for any SLC 500 system. It supplies DC power to the backplane of a local chassis, expansion rack, or remote I/O chassis. Without it, the modules in the chassis cannot operate or communicate with the processor.

This power supply accepts a wide input voltage range. You can feed it 85-132V AC or 170-250V AC, with a frequency of 47 to 63 Hz. The module automatically adapts to the applied voltage.

Additionally, the 1746-P4 provides a 24V DC output. You can use this to power small external devices. However, avoid using it for output modules. Troubleshooting becomes difficult because you must shut down the entire rack to replace a faulty output module.

Key Technical Specifications

The internal current capacity of the 1746-P4 is impressive. It delivers 10.0A at 5V DC and 2.88A at 24V DC to the backplane. Total input power is 92 watts. Typical line power requirement is 180 VA.

Inrush current reaches 45 amps momentarily at startup. The output voltage range for the 24V DC auxiliary output is 18 to 30V DC. Backplane current draw at 24V is 0.46A.

Fuse protection is built into the design. Use a 1746-F1 or an equivalent fuse for replacement.

Hold-Up Time Explained

All SLC 500 power supplies feature hold-up time. This is the ability of the processor to continue running logic when the input voltage drops below normal levels.

For the 1746-P4, hold-up time is 20 ms at full load. At no load, it extends to 3000 ms (3 seconds). If the low voltage condition lasts longer than the hold-up time, the processor stops logic execution. Normal operation resumes automatically when input voltage returns.

Mechanical and Environmental Data

Dimensions of the 1746-P4 are 5.5 x 4.3 x 5.7 inches (140 x 109 x 145 mm). Weight is 2.5 pounds (1.1 kilograms).

Operating temperature ranges from 0°C to 60°C. Storage temperature is not specified but generally follows SLC 500 standards (-40°C to 85°C).

The module mounts directly into the leftmost slot of any 1746 chassis. It occupies the power supply location, not a standard I/O slot.

Certifications and Safety

The 1746-P4 holds several important certifications. It is UL Listed as Industrial Control Equipment.

Furthermore, it is CSA Certified as Process Control Equipment for hazardous locations. Specifically, it meets Class 1, Division 2, Groups A, B, C, D requirements.

This makes the 1746-P4 suitable for use in environments with potentially flammable gases or vapors. Always follow local safety codes during installation.

Installation Guidelines

Installing the 1746-P4 is straightforward. Follow these steps:

1. Ensure the main power source is disconnected.

2. Slide the 1746-P4 into the leftmost slot of the chassis.

3. Press firmly until the module seats fully.

4. Secure the retaining screws at the top and bottom.

5. Connect the AC input wires to the terminals (L1 and L2/N).

6. Connect the ground wire to the chassis ground terminal.

7. Apply power and verify the LED indicator lights up.

Never remove or insert the 1746-P4 while power is applied. This can damage the module and the backplane.

Packaging List

• 1746-P4 power supply module – 1 unit

• Terminal block cover – 1 unit

• Installation instructions (printed)

*Note: No certificates or warranty documents are included in the package. Fuse 1746-F1 is sold separately.*

Shipping Methods

We ship worldwide via FedEx, UPS, or DHL. Tracking numbers are provided within 24 hours of order dispatch.

Frequently Asked Questions (FAQ)

1. Can the 1746-P4 power an expansion chassis?
Yes. The 1746-P4 can power a local chassis, an expansion chassis, or a remote I/O chassis. Each chassis requires its own power supply.

2. What happens if the built-in fuse blows?
You must replace it with a 1746-F1 or an equivalent fuse. The fuse is user-replaceable. Always disconnect power before replacing the fuse.

3. Can I use the 24V DC output for sensors?
Yes, but only for small loads. The 24V DC output is not recommended for output modules. It works well for low-power sensors and indicators.

4. Is the 1746-P4 compatible with all SLC 500 chassis?
Yes. It fits any 1746 series chassis. It always occupies the leftmost slot designated for the power supply.

5. What does the hold-up time mean in practice?
If input voltage drops briefly (e.g., due to a brownout), the 1746-P4 keeps the processor running for 20 ms at full load. This prevents unwanted system resets during short power disturbances.