EMC Precompliance Measurement

AN2316 - Application Note

10/24

2

EMC Precompliance Measurement

Electromagnetic Compatibility (EMC) measurement requires use of the Line Impedance

Stabilization Network (LISN).The LISN operates as a filter between the line and test board,

providing clean energy to the system under test. It collects all the emissions coming from the

systems under test (>9kHz) and sends the noise to the EMC analyzer (see

Figure 4).

Figure 4.

EMC Measurement Schematic

Caution:

For safety reasons, an insulated 1:1 transformer is used to avoid a possible ground current

loop.

1.

EMC AC chopper measurement at 20kHz switching frequency (CISPR-14), per EN55014 standard.

2.

Instrument used: E7400 Agilent Technology

EMC Analyzer

LISN

Insulation

Transformer

AC-Chopper Board

Load

AI12289

Table 1.

AC Chopper EMC Limits

Limit Line

EN55014

Conducted <700W, Motors, Quasi-peak

150kHz to 30MHz

EN55014

Conducted <700W, Motors, Average

150kHz to 30MHz