Class role and where it sits in a panel
The 1SAZ211401R1040: Thermal overload heaters in this class are not standalone protection devices; they are the calibrated resistive elements that pair with an ABB thermal overload relay base. The relay body reads the heater current, derives the motor's thermal model, and trips the contactor on sustained overload — so the heater is the part that defines the ampere range of the assembly. Swapping heaters between frames inside the same family is how a builder dials the trip band to a specific motor nameplate FLC without changing the relay body or the contactor.