The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 08, 2002
Filed:
Mar. 16, 2000
Jean-Paul Audren, Aix les Bains, FR;
Jean Marmonier, Aix les Bains, FR;
Alstom Holdings, Paris, FR;
Abstract
The 4 mA-20 mA type or 0-20 mA type current loop connects an analog sensor ( ) to an acquisition system ( ), 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) into said loop, which current is superposed on the sensor current (Ic) or on the acquisition current (Ia). In a first embodiment, a variable voltage generator ( ) injects the superposition current (Is) by adding it to the acquisition current (Ia), thereby making it possible to check a low-current threshold of the acquisition system ( ). In a 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.