Measuring apparatus and method for detecting moisture at a measurement voltage input of the measuring apparatus

• US 8,322,236 B2
• Filed: 10/15/2009
• Issued: 12/04/2012
• Est. Priority Date: 10/15/2008
• Status: Expired due to Fees

• Current Assignee: Endress + Hauser Conducta Gesellschaft Fur Mess- Und Regeltechnik Mbh + Co. Kg
• Original Assignee: Endress+Hauser GmbH+Co (ENDRESS)
• Inventors: Straub, Herman, Lohmann, Martin, Buschnakowski, Stephan, Uhle, Jorg
• Primary Examiner(s): NOLAND, THOMAS
• Application Number:
  US12/588,428
• Publication Number:
  US 20100109636A1
• Time in Patent Office: 1,146 Days
• Field of Search: 73/10.1, 738/661, 324/71.1, 324/76.11, 324/511, 324602-603, 324/609, 324/750.3, 340/501, 340/510, 340604-605, 340/653
• US Class Current: 73/866.1
• CPC Class Codes: G01N 27/286 Power or signal connectors associated therewith
• CPC Class Codes: G01N 33/5438 Electrodes
• CPC Class Codes: G01N 33/84 involving inorganic compounds or pH

Abstract

A measuring apparatus having a measurement voltage input with at least one input contact for an input voltage of a measuring element and a method for detecting moisture on the measurement voltage input of such a measuring apparatus are provided, wherein the measuring apparatus includes a supplemental voltage source, which delivers at least one supplemental voltage and is connected with a supplemental contact arranged in the region of the at least one input contact.

Claims

1. A measuring apparatus comprising:

a measurement voltage input comprising at least one input contact for an input voltage of a measuring element;

an impedance converter, wherein a high-resistance input of said impedance converter is connected to said at least one input contact of said measurement voltage input, said impedance converter emitting a measurement signal;

a supplemental contact; and

a supplemental voltage source, which delivers at least one supplemental voltage and which is connected with said supplemental contact forming a supplemental grid, said supplemental grid being not conductively connected with the at least one input contact of the measurement voltage input, without presence of moisture, wherein;

said supplemental contact is arranged in the region of said at least one input contact.

2. The measuring apparatus as claimed in claim 1, wherein:

said supplemental voltage source is so provided, that it delivers at least one supplemental voltage of a size, which lies outside of a range of a size of the input voltage.

3. The measuring apparatus as claimed in claim 1, wherein:

said supplemental voltage source is so provided, that it delivers at least a first supplemental voltage and a second supplemental voltage and includes a supplemental voltage switching system, which can be switched between the first supplemental voltage and the second supplemental voltage; and

the second supplemental voltage is a positive voltage.

4. The measuring apparatus as claimed in claim 3, wherein:

said supplemental voltage source includes a microcontroller for operating said supplemental voltage switching system.

5. The measuring apparatus as claimed in claim 1, wherein:

said measurement voltage input further comprising a reference input contact, which is grounded to provide a reference potential.

6. A method for detecting moisture on a measurement voltage input of a measuring apparatus comprising at least one input contact for an input voltage of a measuring element, comprising the steps of:

applying an input voltage of said measuring instrument to said at least one input contact, which is connected to a high-resistance input of an impedance converter, said impedance converter emitting a measurement signal;

producing at least one supplemental voltage by use of a supplemental voltage source and a supplemental contact connected with the supplemental voltage source and arranged in the region of the at least one input contact; and

said supplemental voltage being applied to the supplemental contact, so that, in the case of occurrence of moisture in the region of the at least one input contact, a shunt connection is produced between the at least one input contact and the supplemental contact, so that a size of the input voltage is drawn in the direction of a size of the at least one supplemental voltage.

7. The method as claimed in claim 6, wherein:

a supplemental voltage with a size is delivered, which lies outside of a range of a size of the input voltage.

8. The method as claimed in claim 7, further comprising:

detecting the presence of moisture in the region of the at least one input contact due to the departure of the input voltage from a normal range of the measurement voltage input or due to the departure of the measurement voltage from a normal range of the measurement voltage.

9. The method as claimed in claim 6, further comprising the step of:

switching between at least a first supplemental voltage and a second supplemental voltage.

10. The method as claimed in claim 9, further comprising:

detecting the presence of moisture in the region of the at least one input contact, when the measurement voltage after the switching assumes the same direction of change as the voltage change from the first supplemental voltage to the second supplemental voltage.

11. The method as claimed in claim 6, wherein:

said measuring element being a glass sensor for measuring pH-value.

12. A measuring apparatus, comprising:

a measuring element with large internal resistance, a measurement voltage input comprising at least one input contact for an input voltage of said measuring element connected to said voltage input;

a unit for measurement signal processing comprising an impedance converter, wherein a high-resistance input of said impedance converter is connected to said at least one input contact of said measurement voltage input, said impedance converter providing a measurement signal;

a supplemental contact, which is arranged in the region of said at least one input contact; and

a supplemental voltage source, which delivers at least one supplemental voltage and is connected with said supplemental contact.

13. The measuring apparatus as claimed in claim 12, wherein:

said measuring element with large internal resistance being a glass sensor for measuring pH-value.

14. The measuring apparatus as claimed in claim 12, further comprising:

further circuit parts for additional processing said measurement signal.

15. The measuring apparatus as claimed in claim 12, wherein:

said supplemental contact surrounds said input contact.

16. The measuring apparatus as claimed in claim 12, wherein:

said measurement voltage input further comprising a reference input contact, which is grounded to provide a reference potential.

17. The measuring apparatus as claimed in claim 12, wherein:

said supplemental voltage source is so provided, that it delivers at least one supplemental voltage of a size, which lies outside of a range of a size of the input voltage.

18. The measuring apparatus as claimed in claim 12, wherein:

said supplemental voltage source is so provided, that it delivers at least a first supplemental voltage and a second supplemental voltage and includes a supplemental voltage switching system, which can be switched between the first supplemental voltage and the second supplemental voltage; and

said second supplemental voltage is preferably a positive voltage.

19. The measuring apparatus as claimed in claim 12, wherein:

said supplemental voltage source and said supplemental contact are connected forming a supplemental grid, said supplemental grid being not conductively connected with the at least one input contact of the measurement voltage input, without presence of moisture.