What it is and where it sits
The Mitsubishi FX5-1PSU-5V is a power supply module for the FX5 PLC family, accepting a 100 to 240 V AC supply at 50/60 Hz and drawing 20 W max from the line. It is the slot that feeds the CPU and I/O of an FX5 rack, so the unit's input window and internal fuse are the two numbers that decide whether it drops into a given cabinet.
Input window and tolerance
Rated supply is 100 to 240 V AC with a fluctuation tolerance of -15%, +10% at 50/60 Hz, so the same part number covers both feeds without a tap change.
Internal protection
A 250 V 3.15 A time-lag fuse sits on the supply input. Keep that exact rating in the spares drawer — a fast-blow substitute will nuisance-trip on transformer inrush at switch-on.