What it is
The ABB 1SAZ721201R1033 is a solid state overload relay catalogued under the Circuit Breakers, Fuses & Protection › Relays › Solid State Overload Relays class. It belongs to ABB's electronic motor-protection family — the solid state variant that replaces legacy thermal-bimol heaters with a current-transformer-based sensing element and an adjustable trip curve, so the panel gets tighter repeatability and a wider setting range than a thermal unit can deliver. Because the trip characteristic is set in firmware rather than by a heater pack, one ABB solid state relay can cover an amp range that would otherwise need several thermal overloads — useful when the cabinet holds a mix of motor sizes and you want one spare pattern on the shelf.
Where this class sits in a panel
In a typical motor-starter build the solid state overload sits directly under the contactor, carrying the motor's load current through its CT loops while its auxiliary output feeds the contactor coil and the PLC fault word. That placement is what gives the device its value: it watches running current continuously and trips the contactor on sustained overload without the slow heater-warm-up a thermal unit needs. Because it lives on the same DIN-rail footprint as the matching ABB contactor family, wiring lands on the same pass-through terminals — the swap from a thermal overload to this solid state part is usually a same-rail drop-in once the setting range and CT loop count match the motor nameplate.