Allen-Bradley 1746-P1 SLC 500 Power Supply Module

The Allen-Bradley 1746-P1, also cataloged as the 1746-P1 Power Supply Module, operates as a dedicated hardware component for AC-to-DC system power conversion and backplane power distribution within SLC 500 chassis assemblies.

Hardware Specifications

Deterministic Backplane & I/O Density Scaling

The 1746-P1 mounts on the left side of the SLC 500 rack, delivering regulated 5 VDC and 24 VDC rails to the internal backplane bus to power CPUs, I/O cards, and communication adapters. The module provides continuous voltage stabilization with a CPU hold-up time between 20 ms (full load) and 3000 ms (no load), insulating system processors from momentary AC line sags. Backplane bus communication velocity and logic synchronization remain uninterrupted across dense local I/O module configurations during line transients, maintaining system integrity before firmware-triggered shutdown sequences occur.

Frequently Asked Questions

Q: How must the AC line input voltage jumper be set on the 1746-P1 module before applying field power?

A: The physical input jumper must be configured for either 120 VAC or 220 VAC operation prior to applying line power, as exposed pins carry hazardous line voltages during energization.

Q: What are the backplane current output limits for sizing SLC 500 rack modules?

A: The power supply delivers a maximum backplane current capacity of 2 A at 5 VDC and 0.46 A at 24 VDC, alongside a auxiliary 200 mA user power loop at 18 to 30 VDC.

Q: How does the power supply handle ambient thermal derating above 55 deg C?

A: Continuous current output capacity must be derated by 5% for ambient operating temperatures exceeding 55 deg C up to the maximum limit of 60 deg C.

Field Installation Guidelines

Mount the 1746-P1 on the far-left side of the SLC 500 chassis frame using the designated mounting screws. Ensure line power is completely turned off before removing protective terminal covers or adjusting the AC input voltage selector jumper.

Connect AC line power, neutral, and chassis earth ground to the screw terminal block. Install an external 15 A maximum branch circuit overcurrent protective device upstream of the module. Wire the main protective earth (PE) lug directly to the control cabinet ground bus bar with low-impedance copper wire. Maintain adequate vertical clearance around the power supply heat sink fins to permit convective cooling across the entire 0 to 60 deg C operating range.