Electricity: measuring and testing – Impedance – admittance or other quantities representative of... – Parameter related to the reproduction or fidelity of a...
Reexamination Certificate
1999-03-12
2001-06-05
Metjahic, Safet (Department: 2858)
Electricity: measuring and testing
Impedance, admittance or other quantities representative of...
Parameter related to the reproduction or fidelity of a...
C324S529000, C324S530000
Reexamination Certificate
active
06242925
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to electromagnetic interference (EMI) susceptibility testing.
Conventional EMI susceptibility testing methods involve subjecting electrical equipment under test (EUT) to large, externally radiated fields and to thereby attempt to create electromagnetically induced equipment failures. Such methods quantify EMI susceptibility for the equipment under test as a whole, but provide no information on a particular failure mechanism; hence, it is very difficult to pinpoint which subcircuit is failing in the EUT. Furthermore, such methods require application of a large external field, sometimes destroying the EUT before the non-destructive susceptibility level can even be determined. Moreover, it is often difficult to externally generate the large fields required to induce failure in the EUT.
Another approach to EMI susceptibility testing involves bulk current injection (BCI), i.e., the injection of high-frequency currents into harness wires. BCI also allows for quantification of the overall board susceptibility, but as with the methods described hereinabove, it is difficult with BCI to determine which subcircuit is actually failing. And continuous energy applied using BCI can likewise destroy the EUT.
Accordingly, it is desirable to provide non-destructive EMI susceptibility testing of electrical equipment which allows for quantification of equipment susceptibility and which provides information regarding particular failure mechanisms of the EUT.
BRIEF SUMMARY OF THE INVENTION
Non-destructive EMI susceptibility testing involves near-field injection of very high levels of instantaneous energy and low average power. More specifically, this involves localized injection of signals of very high field strength and low duty cycle. An electric field (E-field) injector and a magnetic field (H-field) injector are scanned, each in turn, over the EUT. For each injector, the amplitude and frequency of the induced localized electric or magnetic field, respectively, are varied such that the susceptibility locations, magnitudes, and frequencies of the EUT can be identified and mapped. This allows simple, low-cost board modifications for the EUT for improving EMI susceptibility. Furthermore, this approach localizes which section or subcircuit of the EUT is susceptible, the frequencies and field strengths of susceptibility, and whether susceptibility problems are created by magnetic fields, electric fields, or both.
REFERENCES:
patent: 5701082 (1997-12-01), Rogers
patent: 6121779 (2000-09-01), Schutten et al.
“Bulk Current Injection System,” MJ Schutten; WG Earls, Serial No. 09/134,800 (GE docket RD-26,172), filed Aug. 14, 1998.
Earls William George
Schutten Michael Joseph
Breedlove Jill M.
General Electric Company
Kerveros James C.
Metjahic Safet
Stoner Douglas E.
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