Controller device, adapted to control the starting and running of an electric motor, said electric motor being an induction motor and being a motor of a compressor in a refrigeration system, said controller device comprising: - a control element which can be activated on a motor of a compressor to regulate a starting condition and a running condition thereof, said control element comprising a detection element for performing a measurement of operating electrical parameters, said operating electrical parameters comprising at least one current flow, and a memory for storing said measurement of said operating electrical parameters; and - switching means (20, 21) operatively serving said control element and capable of being controlled to allow and stop a supply of electrical energy to a starting winding and to a running winding of said motor respectively; and - a safety means controllable by said control element to open or close a supply circuit of said induction motor, said control element being made in the form of a relay which can be physically opened or interrupted, characterized in that said control element is adapted to: - close the safety means before an activation of an amperometric load on said starting winding and/or on said running winding; - perform a check, preferably periodic, of a correct operation of the control element itself, so that if it results from said check that said control element does not operate correctly, said safety means would be opened, otherwise it would remain closed; - supply the running winding; - store an initial value of said operating electrical parameters, said initial value of operating electrical parameters comprising a current flow of the running winding; - supply the starting winding to start said motor; - monitor a current value of said operating electrical parameters of the motor and compare it as a function of an initial value of the operating electrical parameters of the running winding; and - interrupt the power supply to the motor, if it results from said monitoring that said current value of the motor is greater than a predetermined value. - a control element which can be activated on a motor of a compressor to regulate a starting condition and a running condition thereof, said control element comprising a detection element for performing a measurement of operating electrical parameters, said operating electrical parameters comprising at least one current flow, and a memory for storing said measurement of said operating electrical parameters; and - switching means (20, 21) operatively serving said control element and capable of being controlled to allow and stop a supply of electrical energy to a starting winding and to a running winding of said motor respectively; and - a safety means controllable by said control element to open or close a supply circuit of said induction motor, said control element being made in the form of a relay which can be physically opened or interrupted, - close the safety means before an activation of an amperometric load on said starting winding and/or on said running winding; - perform a check, preferably periodic, of a correct operation of the control element itself, so that if it results from said check that said control element does not operate correctly, said safety means would be opened, otherwise it would remain closed; - supply the running winding; - store an initial value of said operating electrical parameters, said initial value of operating electrical parameters comprising a current flow of the running winding; - supply the starting winding to start said motor; - monitor a current value of said operating electrical parameters of the motor and compare it as a function of an initial value of the operating electrical parameters of the running winding; and - interrupt the power supply to the motor, if it results from said monitoring that said current value of the motor is greater than a predetermined value.