Powering the SLC 500 Without Costly Downtime
When an SLC 500 line goes dark, every minute of downtime carries a real cost. The Allen-Bradley 1746-P2 is the modular power supply that keeps that platform alive. It mounts in the leftmost slot of a 1746 chassis and converts 120 to 220 Volts AC into the backplane power your processor and I/O modules need. For plants running legacy SLC 500 systems, having this module ready-to-ship is often the difference between a quick swap and a stalled shift.
What the 1746-P2 Delivers
The 1746-P2 accepts 120 to 220 Volts AC input with a 70 Watt input power rating and a typical line power requirement of 180 VA. A jumper terminal lets you set the correct input voltage for your supply. The module provides 5 amps of backplane current at 5 Volts and 0.46 Amps at 24 Volts, with an internal current capacity of 5 A at 5V DC and 0.96 A at 24V DC. Its 24V DC output voltage range spans 18 to 30 Volts DC.
That 5 A backplane budget matters when you are counting I/O modules. Undersized supply capacity forces you to split racks or add hardware, both of which raise system cost. The 1746-P2 gives you headroom for a fully loaded chassis, so you buy the modules you need instead of the modules the supply can carry.
Technical Specifications
The table below lists the key parameters for this exact model. Every value comes directly from the manufacturer data for the 1746-P2.
| Specification | Value |
|---|---|
| Series | SLC 500 |
| Module Type | Power Supply |
| Input Voltage | 120 to 220 Volts AC |
| Input Power | 70 Watts |
| Frequency | 47 to 63 Hertz |
| Backplane Current (5V) | 5 Amps |
| Backplane Current (24V) | 0.46 Amps |
| Output Voltage Range | 18 to 30 Volts DC |
| Inrush Current | 20 Amps |
| CPU Hold-Up Time | 20 ms (full load); 3000 ms (no load) |
| Operating Temperature | 0 to 60 Celsius |
| Dimensions | 5.5 x 3.3 x 5.7 inches |
| Weight | 1.1 kg (2.5 lbs) |
| Fuse Protection | 1746-F1 or equivalent |
Where the 1746-P2 Earns Its Keep
In oil and gas facilities, SLC 500 racks often run valve control, pump monitoring, and safety interlocks. The 47 to 63 Hertz input range handles both 50 and 60 Hz supplies, so the same module works across regions without a different part number. That single-part flexibility cuts spares inventory cost for multi-site operations.
In water treatment and packaging lines, the 20 ms hold-up time at full load keeps the CPU running through brief voltage sags. The 3000 ms hold-up time at no load gives you even more buffer during light-load conditions. Fewer nuisance shutdowns means fewer restarts and less scrap.
Installation and Setup Notes
The 1746-P2 installs in the leftmost position of a 1746 chassis. This slot is not counted in the slot numbering, which starts at Slot Zero for the processor or communication adapter. Open the front cover to reach the five terminals, jumper pins, and internal fuse. The terminals accept AC line, DC power, and ground connections, with a maximum of two AWG wires per terminal.
Set the jumper pins to match your supply: 100/120 VAC or 200/240 VAC. Always work with input power inactive. Connecting or disconnecting a wire under load can produce an electric arc that damages the electronic backplane. If high-inductive loads share the supply, an isolation transformer can prevent voltage surges from reaching the module.
Maintenance and Reliability
The internal fuse protects against short-circuit fire hazards, and its replacement equivalent is 1746-F1. Inspect terminal connections periodically and confirm the jumper setting matches your line voltage. Keep the chassis within the 0 to 60 Celsius operating range. Because the 1746-P2 is a legacy SLC 500 component, please verify current lifecycle status and availability with Oil AutoTech before ordering.
Sourcing the 1746-P2
For overcurrent conditions, Series A and B units shut down the supply and fault the CPU, requiring a program reload. Series C units shut down only the 24V DC user supply while the CPU keeps running. Know which revision you run before you buy. Oil AutoTech provides hands-on technical selection help and fast dispatch, worldwide. Contact Oil AutoTech today for pricing and availability.
