Inductive proximity switch with sensor coil protected by wall - has shock protection if contact panel broken, given by isolating capacitors in coil leads to prevent flow of DC

摘要

An inductive proximity switch, with a sensor coil protected by a wall from contact with an operating person, which is connected to an oscillator with a trigger circuit; as a further precaution to protect operating persons if the protective wall is damaged, the sensor coil (10a, 10b) is galvanically isolated from the oscillator (13) by isolating condensers (35-37) in all its leads. Alternatively, the oscillator (13) may be connected through high value protective resistors (19, 39) and coupling condensers (40, 42) and a charging condenser (41) to the trigger stage (20).