Shut=off assembly for electronically-controlled drive of working machine - monitoring load current by sensor coupled to differentiator, threshold switch and main switch for control electronics

摘要

A current sensor (3) is installed in the current path between the power source (1) and the control electronics (2) for the drive (7). The sensor generates a voltage signal proportional to the current and this is passed to a differentiating circuit (4) whose output signal is proportional to the acceleration of the drive. Along with a reference signal, it is passed to a threshold switch (5) and the main switch (6). The output of the latter turns off the control electronics when necessary. An alternative circuit has a low-pass circuit between the current sensor and the differentiating circuit with a second threshold switch and a delay circuit as extra inputs to the main switch. USE/ADVANTAGE - Prevents damage, e.g. to biological tissue, during sudden load change by monitoring load current esp. in medical drill for surgical treatment of bone fractures.