A method, comprising: receiving (1415, 1435), at a control unit, a user-specified overload time setting or a user-specified overload amperage setting associated with a protection device (Protection device 1-n) connected in series with a load (LOAD 1-n), measuring (1425, 1445), by the control unit, a current through a power transistor or an overload time associated with the current, wherein the power transistor supplies the current to the load and the protection device and wherein the overload time comprises an elapsed time since a beginning of an increase in the current through the power transistor; measuring, by the control unit, a temperature of a base plate of a module that includes the power transistor, wherein the base plate of the module is coupled to a heat sink via a heat conducting material; and determining, by the control unit, a temperature T 2 of the heat sink based on the measured temperature of the base plate of the module that includes the power transistor; using, by the control unit, a mathematical expression, that relates the determined temperature T 2 and the measured current to a maximum power transistor overload time, to determine a maximum power transistor current increase for the user-specified overload time setting or to determine a specific maximum power transistor overload time for the user-specified overload amperage setting; and selectively turning off (1430, 1450) the power transistor based on: a) whether the measured current equals or exceeds the determined maximum power transistor current increase, or b) whether the measured overload time equals or exceeds the determined specific maximum power transistor overload time. receiving (1415, 1435), at a control unit, a user-specified overload time setting or a user-specified overload amperage setting associated with a protection device (Protection device 1-n) connected in series with a load (LOAD 1-n), measuring (1425, 1445), by the control unit, a current through a power transistor or an overload time associated with the current, wherein the power transistor supplies the current to the load and the protection device and wherein the overload time comprises an elapsed time since a beginning of an increase in the current through the power transistor; measuring, by the control unit, a temperature of a base plate of a module that includes the power transistor, wherein the base plate of the module is coupled to a heat sink via a heat conducting material; and determining, by the control unit, a temperature T 2 of the heat sink based on the measured temperature of the base plate of the module that includes the power transistor; using, by the control unit, a mathematical expression, that relates the determined temperature T 2 and the measured current to a maximum power transistor overload time, to determine a maximum power transistor current increase for the user-specified overload time setting or to determine a specific maximum power transistor overload time for the user-specified overload amperage setting; and selectively turning off (1430, 1450) the power transistor based on: a) whether the measured current equals or exceeds the determined maximum power transistor current increase, or b) whether the measured overload time equals or exceeds the determined specific maximum power transistor overload time. a) whether the measured current equals or exceeds the determined maximum power transistor current increase, or b) whether the measured overload time equals or exceeds the determined specific maximum power transistor overload time.