首页>
外国专利>
A test circuit characterised by an in-built diagnostic system where the circuit is connected in parallel with a current loop where a test current is injected and is superimposed on either the sensor or acquisition current loop
A test circuit characterised by an in-built diagnostic system where the circuit is connected in parallel with a current loop where a test current is injected and is superimposed on either the sensor or acquisition current loop
The 4 mA-20 mA type or 0-20 mA type current loop connects an analog sensor (1) to an acquisition system (3), respectively carrying a sensor current (Ic) and an acquisition current (Ia). A test circuit is connected in parallel with the current loop to inject a superposition current (Is) in the loop. The current is superposed on the sensor current (Ic) or on the acquisition current (Ia). In the first embodiment, a variable voltage generator (7) injects the superposition current (Is) by adding it to the acquisition (Ia), thereby making it possible to check a low current threshold of the acquisition system (3). In the second embodiment, a variable current regulator injects the superposition current (Is) by adding it to the sensor current (Ic), thereby making it possible to check a high current threshold of the acquisition system. The high and low current thresholds of the acquisition system are tested without opening the current loop.
展开▼
