An apparatus, comprising: a plurality of current transformers (CT1, CT2, CT3) associated with an overload relay, connecting with corresponding phases of a three-phase power system providing power to a three-phase motor, each current transformer providing a value representative of current measurement input updates of current flow it senses through each corresponding phase of the three-phase power system; at least one processor associated with the overload relay, coupled to the plurality of current transformers; at least one memory associated with the overload relay, including computer program code, wherein the computer program code, when executed by operation of the at least one processor, performs an operation comprising: receiving values representative of current measurement input updates of current flow sensed by the current transformers corresponding to phases of the three-phase power system providing power to the three phase induction motor; computing an updated average current of the received current measurement input updates; adjusting a threshold for a detected current phase unbalance at which the overload relay will be tripped, as a function of a ratio of the updated average current to motor full load current, wherein a thermal curve with an unbalance protection threshold setting intersects a fixed unbalance protection setting trip time at a current cross-over point in a graph of trip time versus a ratio of the updated average current to motor full load current, and wherein the function is a straight line in a graph of current unbalance versus the ratio of the updated average current to motor full load current, the straight line having a slope equal to a slope of an ideal motor heating model at the current cross-over point; increasing the adjusted threshold for a detected current phase unbalance at which the relay will be tripped, when the ratio of the updated average current to motor full load current decreases; and decreasing the adjusted threshold for a detected current phase unbalance at which the relay will be tripped, when the ratio of the updated average current to motor full load current increases. a plurality of current transformers (CT1, CT2, CT3) associated with an overload relay, connecting with corresponding phases of a three-phase power system providing power to a three-phase motor, each current transformer providing a value representative of current measurement input updates of current flow it senses through each corresponding phase of the three-phase power system; at least one processor associated with the overload relay, coupled to the plurality of current transformers; at least one memory associated with the overload relay, including computer program code, wherein the computer program code, when executed by operation of the at least one processor, performs an operation comprising: receiving values representative of current measurement input updates of current flow sensed by the current transformers corresponding to phases of the three-phase power system providing power to the three phase induction motor; computing an updated average current of the received current measurement input updates; adjusting a threshold for a detected current phase unbalance at which the overload relay will be tripped, as a function of a ratio of the updated average current to motor full load current, wherein a thermal curve with an unbalance protection threshold setting intersects a fixed unbalance protection setting trip time at a current cross-over point in a graph of trip time versus a ratio of the updated average current to motor full load current, and wherein the function is a straight line in a graph of current unbalance versus the ratio of the updated average current to motor full load current, the straight line having a slope equal to a slope of an ideal motor heating model at the current cross-over point; receiving values representative of current measurement input updates of current flow sensed by the current transformers corresponding to phases of the three-phase power system providing power to the three phase induction motor; computing an updated average current of the received current measurement input updates; adjusting a threshold for a detected current phase unbalance at which the overload relay will be tripped, as a function of a ratio of the updated average current to motor full load current, wherein a thermal curve with an unbalance protection threshold setting intersects a fixed unbalance protection setting trip time at a current cross-over point in a graph of trip time versus a ratio of the updated average current to motor full load current, and wherein the function is a straight line in a graph of current unbalance versus the ratio of the updated average current to motor full load current, the straight line having a slope equal to a slope of an ideal motor heating model at the current cross-over point; increasing the adjusted threshold for a detected current phase unbalance at which the relay will be tripped, when the ratio of the updated average current to motor full load current decreases; and decreasing the adjusted threshold for a detected current phase unbalance at which the relay will be tripped, when the ratio of the updated average current to motor full load current increases.