INTRINSICALLY SAFE AUTOMATION FIELD DEVICE

摘要

The invention relates to an intrinsically safe automation field device comprising: - connecting terminals (30a, 30b) via which a current (Is) can be supplied; - a sensor and/or actuator element (16); - a field device electronic system (31, 32, 33, 34, 36) having a current path (50) between the connecting terminals (30a, 30b) and a voltage regulator (36) which is introduced into the current path (50) and is designed to provide a power supply (16) on the basis of the current (Is); - an explosion protection unit (35, 38) comprising at least two actively controllable switching elements (38a, 38b) introduced in series into the current path (50) and two threshold value circuits (35a, 35b) which are designed such that a first threshold value circuit (35a) actuates a first switching element (38a) in accordance with a first threshold value and a second threshold value circuit (35b) actuates a second switching element (38b) in accordance with a second threshold value such that, when the first and/or second threshold value is reached, the current (Is) is limited to the first and/or second threshold value, and the threshold value circuits (35a, 35b) are connected in parallel to the voltage regulator (36).