Allen-Bradley 1746-P2​ SLC 500 Rack Power Supply – 5 A @ 5V DC, 120/240V AC Input

Technical Specifications

Main Features and Advantages

A 5A logic rail that actually covers a real rack.​ The published weakness of the smaller 1746-P1​ is its 2.0 A 5V budget, which forces a second chassis or a careful module diet. The 1746-P2​ doubles that headroom to 5.0 A and pushes the 24V backplane rail to 0.96 A, which is why it is the default fit for a 1746-A7 or a medium-density 1746-A10. A processor, a DH+ or Ethernet module, several 16-point DC input cards and a pair of analog channels will usually sit comfortably inside the 70 W combined ceiling, provided you do the worksheet instead of guessing.Jumper-selected, not auto-sensing — and that is a safety feature.​ The line-voltage selector on the 1746-P2​ must be matched to the applied mains with the supply powered down. There is no “universal input” ambiguity and no firmware setting to misread: what you set is what the magnetics expect. It also means a technician can verify the jumper position visually during a swap, which prevents the classic mistake of landing 230V onto a supply still set for 120V. The published 85…132 / 170…265 V AC windows give plenty of tolerance for brownouts and regional voltage drift.The 200 mA user tap is a panel-space saver, properly understood.​ That isolated 18…30V, 200 mA output on the 1746-P2​ is there for small, trusted loads — a few 24V DC sensors on a 1746-IB16, a panel-mounted selector, a handheld terminal. It is current-limited and it is not fused at the terminal, so a dead short shows up as a dropped user rail rather than a tripped breaker. The disciplined rule is simple: anything above a couple of sensor loads moves to an external 24V DIN-rail supply, and the 1746-P2​ user output stays a convenience, not an infrastructure item.Hold-up that rides through the bumps.​ Twenty milliseconds at full load is enough to survive a contactor drop or a genset transfer blip without the processor faulting, and the no-load figure rises to 3000 ms, which is why a chassis with light I/O often shrugs off a power flicker that would reset a less buffered controller. Couple that with 1800V AC RMS isolation between line and backplane, and the 1746-P2​ earns its place in electrically noisy cells — welders, large contactors, VFD-heavy panels — where the AC common-mode junk would otherwise walk down the supply and into the logic rail.Series behaviour you should know before you blame the CPU.​ Earlier 1746-P2​ series (A and B) treated a user-output overcurrent as a supply-wide fault: the CPU was forced into fault and the user program had to be reloaded after the condition was cleared. Series C changed that to a local user-rail shutdown while the 5V logic rail and the processor keep running, so clearing the short restores the 24V tap without a restart. If you are swapping into an old rack, the series letter on the nameplate matters — a new 1746-P2/C​ behaves better than the unit it replaces, but the rest of the rack will not notice the difference.