Measuring and limiting EMI with a differential mode rejection network
US4849685A · kind A · utility
Inventor
Key dates
| Filing date | Oct 1, 1987 |
| Grant date | Jul 18, 1989 |
| Priority date | — |
| Expiry date | Oct 1, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R29/0814
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Measurement of electromagnetic interference (EMI), especially conducted emissions from electrical equipment under test (EUT) to transmission lines powering the EUT; and then limiting such EMI. Differential mode (as distinguished from common mode) EMI conducted emissions are excluded temporarily from measurement by interposing a differential mode rejection network (DMRN) between the EUT and an EMI-sensitive receiver, and such common mode EMI is measured. A filter against such common mode conducted emissions is designed and is interposed between the EUT and the EMI receiver, and such differential mode EMI is then measured--with the DMRN removed. A filter against the differential mode conductive emissions is also designed and interposed between the EUT and the receiver, and the total conducted emissions are rechecked. The respective filters are combined into a composite filter for the EUT to prevent such EMI conductive emissions from entering power transmission lines.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.