Static conductivity tester

• US 4,742,295 A
• Filed: 10/28/1985
• Issued: 05/03/1988
• Est. Priority Date: 10/28/1985
• Status: Expired due to Fees

• Current Assignee: Hawker Energy Products Limited
• Original Assignee: Gates Rubber Company (Gates Industrial Corp. Plc)
• Inventors: Fahlberg, Roger, Shepherd, James D., Nahman, Vance
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): Solis, Jose M.
• Application Number:
  US06/791,879
• Time in Patent Office: 918 Days
• Field of Search: 324/51, 324/54, 324/62-65, 324/133
• US Class Current: 324/133
• CPC Class Codes: G01R 27/025 Measuring very high resistances, e.g. isolation resistances, i.e. megohm-meters

Abstract

An elastomeric belt and hose conductivity testing device incorporating a comparator network to verify that a belt or hose is either conductive or nonconductive (resistive) of the flow of static electricity. The device indicates whether the article being tested has a resistivity or conductivity which meets the industry standard of resistivity or conductivity for that particular article. The testing device is battery powered so that it is easily portable for use in the field.

Claims

1. A tester for comparing the resistivity or conductivity of an elastomeric article against a predetermined standard to determine its suitability for a specific application, said tester comprising:

a direct current voltage source capable of supplying the tester with a source electrical potential;

means for flowing the electrical current of the testing device through the elastomeric article to be tested;

switching mechanism circuitry with multiple settings that provides a means for selecting one of the settings, each setting selected to trip a switch within the switching mechanism circuitry that corresponds to a particular configuration of electrical components to correspond to a type of test;

wherein at least one setting is capable of checking the source electrical potential of the direct current voltage source so that the output indicator will indicate "pass" if the direct current voltage source is holding a voltage sufficient to supply the tester with the source electrical potential necessary to allow the tester to test the elastomeric articles against the predetermined standards;

a comparator network comprising two direct current differential-input comparator amplifiers, each amplifier having a first inverting and second non-inverting input terminal and an output terminal, wherein each of the first inverting input terminals is connected to a reference branch circuit comprising at least one known resistance and the source electrical potential, and wherein each of the second non-inverting input terminals is connected to an input test branch circuit comprising the source electrical potential, the switching mechanism, and the means for flowing the electrical current;

the comparator network serving to compare the potential generated from the reference branch circuit with the potential generated from the input test branch circuit; and

an output indicator comprising a "fail" indication means connected to one of the two comparator amplifiers by way of its output terminal, and a "pass" indication means connected to the other one of the two comparator amplifiers by way of its output terminal;

the output indicator to indicate "pass" when the potential generated from the input test branch circuit exceeds the potential generated from the reference branch circuit, and the output indicator to indicate "fail" when the potential generated from the reference branch circuit exceeds the potential generated from the input test branch circuit.

2. The tester of claim 1 wherein the means for flowing electric current through the elastomeric article of unknown resistance is by the use of probes placed a specific distance apart on the article.

3. The tester of claim 1, wherein the direct current voltage source is a suitable electrochemical battery means, and wherein the comparator network is protected from gross overvoltage and excess current by connecting a first, second, and third branch to the input test branch circuit and placing a current-limiting resistor into the input test branch circuit, the first branch comprising a diode and the source electrical potential, the second branch comprising a diode, and the third branch comprising a capacitor.