What it is, and what it does on the panel
The ABB 1SAZ511201R1002 is a thermal overload heater from the Thermal Overload Heaters for Starters line, sitting under Contactors and Starters inside the broader Circuit Breakers, Fuses & Protection tree (–). It is the heater element that drops into the matching ABB overload relay frame and trips the starter when sustained motor current exceeds the calibrated window — the classic electromechanical motor protection path for direct-on-line starters. Body and termination geometry are defined by the relay it pairs with; the order code is what locks the current range to the contactor size, so a procurement line keyed to 1SAZ511201R1002 has to be matched, not approximated. Catalogue description on record reads 1SAZ511201R1002 — THERMAL OVERLOAD by ASEA BROWN BOVERI.