Measuring instrument for fill level sensors

US6404209B1 · kind B1 · utility

Assignee

• GESTRA AG · DE

Inventors

• Juergen Klattenhoff · Delmenhorst, DE
• Guenter Schmitz · Oldenburg, DE
• Holger Schroeter · Braunschweig, DE

Key dates

• Filing date: Jun 20, 2000
• Grant date: Jun 11, 2002
• Expiry date: Aug 24, 2020

Classification

• Technology area (CPC G): Physics
• CPC primary: G01R17/02
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A measuring instrument (11) for fill level sensors (4) having a measuring electrode (6) and a compensating electrode (9). The measuring instrument (11) has a bridge circuit whose one bridge branch (21) is formed by two series-connected test resistors (23, 24). The other bridge branch (22) is formed by the measuring resistor (17) on the measuring electrode (6) and the compensating resistor (18) on the compensating electrode (9). Between the two bridge branches (21, 22) a diagonal line (26) with a test switch (27) is provided. The measuring instrument (11) is controlled by the control circuit (13) so that the diagonal line (26) is closed outside of preset test time periods, and interrupted at preset test time periods. The end of the diagonal line (26) located between the two test resistors (23, 24) is connected to the base potential (25) of the measuring circuit (12). The resistors (17, 18, 23, 24) are designed so that when the test switch (27) is closed, the imbalance of the bridge is determined by the second bridge branch (22), whereas when the test switch (27) is open, the imbalance of the bridge is determined by the first bridge branch (21), simulating in this way a situation in …