Nonlinearity detection using fault-generated second harmonic
US4496900A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 30, 1982 |
| Grant date | Jan 29, 1985 |
| Priority date | — |
| Expiry date | Apr 30, 2002 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T29/49004
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The tester and method for nondestructively detecting nonlinearity faults in conductors includes the application of a composite AC and DC drive signal to the device under test in such manner that nonlinearities in the device under test produce fault signals including second harmonics, due to local changes of resistance caused by ohmic heating. Electronic filters are used to select out and amplify the second harmonic only, eliminating the direct current and fundamental frequency components of the initial test pulse, plus third and subsequent harmonics. The filtered second harmonic signals from the device under test are then phase-compared to a phase-shifted second harmonic signal produced by a frequency doubler from the test signal generator oscillator to cancel out the second harmonic signals from the good conductor; the remaining phase anomaly signals control a threshold detector remaining to provide fault indication.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.