A system for detecting overloads of a motor, comprising: a contactor feeding three phase power to a motor via a plurality of lead lines including a first lead line, a second lead line, and a third lead line, wherein the contactor is an electrically controlled switch for switching the lead lines; the motor coupled to the plurality of lead lines (A; B; C) and configured to receive power via the plurality of lead lines (A; B; C); and a terminal box comprising a sensing device, a first circuit sensing relay and a second circuit sensing relay, the first circuit sensing relay being employed on the first lead line, the first lead line being a lead line for a first phase of the motor, the second circuit sensing relay being employed on the second lead line, the second lead line being a lead line for a second phase of the motor, wherein the sensing device is configured to sense a temperature of the motor via at least one temperature sensor embedded in a third phase of the motor; wherein the first circuit sensing relay is electrically coupled to the motor; wherein the sensing device,the first circuit sensing relay and the second circuit sensing relay are configured to control the contactor; wherein the first circuit sensing relay is configured to detect a current of the motor and trigger a first contact of the contactor corresponding to the first lead line that is associated with the first circuit sensing relay when the current equals or exceeds a trip value, wherein the first circuit sensing relay and the second circuit sensing relay are configured to remain closed while the current is below the trip value and open while the current is equal to or exceeds the trip value. a contactor feeding three phase power to a motor via a plurality of lead lines including a first lead line, a second lead line, and a third lead line, wherein the contactor is an electrically controlled switch for switching the lead lines; the motor coupled to the plurality of lead lines (A; B; C) and configured to receive power via the plurality of lead lines (A; B; C); and a terminal box comprising a sensing device, a first circuit sensing relay and a second circuit sensing relay, the first circuit sensing relay being employed on the first lead line, the first lead line being a lead line for a first phase of the motor, the second circuit sensing relay being employed on the second lead line, the second lead line being a lead line for a second phase of the motor, wherein the sensing device is configured to sense a temperature of the motor via at least one temperature sensor embedded in a third phase of the motor; wherein the first circuit sensing relay is electrically coupled to the motor; wherein the sensing device,the first circuit sensing relay and the second circuit sensing relay are configured to control the contactor; wherein the first circuit sensing relay is configured to detect a current of the motor and trigger a first contact of the contactor corresponding to the first lead line that is associated with the first circuit sensing relay when the current equals or exceeds a trip value, wherein the first circuit sensing relay and the second circuit sensing relay are configured to remain closed while the current is below the trip value and open while the current is equal to or exceeds the trip value.