Charles R Kirklen

US Patent:

39873900, Oct 19, 1976

Filed:

Apr 29, 1974

Appl. No.:

5/465393

Inventors:

Charles A. Kirklen - Richardson TX
Charles F. Rhodes - Richardson TX

Assignee:

Sun Oil Company (Delaware) - Dallas TX

International Classification:

G01R 2702

US Classification:

324 62

Abstract:

The radio frequency resistance between a pair of conductive elements, for example, adjacent pipe sections of a pipeline, which are coupled together through an insulator, may be determined by contacting each pipe section with one of a pair of probes or electrodes connected across the output of a radio frequency oscillator which is coupled to the input of a rectifier and filter circuit. The probes are connected across the oscillator output through a resistor which insures that the direct current output of the rectifier is directly proportional to the RF resistance between the pipe sections. The output of the rectifier is coupled to a meter through an operational amplifier. The meter, which provides a direct readout of the resistance being measured, may be provided with a current limiting circuit which protects the meter from excessive DC current. Calibrating means may be provided to enable adjustment of the gain of the operational amplifier for resistance readings within several ranges.