CIRCUIT FOR DETECTING THE FAILURE OF A STEP MOTOR TO RESPOND TO ENERGIZATION COMMANDS

摘要

Circuit for detecting the failure of a step motor to respond to energization commands, which exploits the time constant decrease of an energized phase which occurs owing to the motor stalling and to its incapacity to execute the rotation imposed by the phase energization. A prefixed current level I in the energized phase is then reached in a time interval TI shorter than the one TO necessary to reach the same current level in case of correct response of the motor.
The circuit comprises a timer having a prefixed period comprised between TI and TO which activates a bistable circuit indicative of failure to respond if the Current level I is reached in a time shorter than the timer period.