NONDESTRUCTIVE EDDY CURRENT TESTING

Patent · Tue May 23 04:00:00 EDT 1961

OSTI ID:4018579

Renken, Jr, C J

An eddy current testing device is described for measuring metal continuity independent of probe-to-sample spacing. An inductance would test probe is made a leg of a variable impedance bridge and the bridge is balanced with the probe away from the sample. An a-c signal is applied across the input terminals of the bridge circuit. As the probe is brought into proximity with the metal sample, the resulting impedance change in the probe gives an output signal from the bridge whose phase angle is proportional to the sample continuity and amplitude is proportional to the probe-tosample spacing. The output signal from the bridge is applied to a compensating network where, responsive to amplitude changes from the bridge output signal, a constant phased voltage output is maintained when the sample is continuous regardless of probe-to-sample spacing. A phase meter calibrated to read changes in resistivity of the metal sample measures the phase shift between the output of the compensating network and the original a-c signal applied to the bridge.

• Research Organization: Originating Research Org. not identified
• NSA Number: NSA-15-017123
• Assignee: U.S. Atomic Energy Commission
• Patent Number(s): US 2985824
• OSTI ID: 4018579
• Country of Publication: United States
• Language: English

Related Subjects

BRIDGE CIRCUITS
CIRCUITS
CURRENTS
EDDY CURRENTS
ELECTRIC CONDUCTIVITY
ELECTRIC METERS
ELECTRIC POTENTIAL
ELECTRIC PROBES
ENGINEERING AND EQUIPMENT
IMPEDANCE
MATERIALS TESTING
MEASURED VALUES
METALS
SIGNALS
STANDARDS
VARIATIONS