| The paper refers to theoretical and practical considerations concerning conducted electromagnetic interferences (IEM). The standards used for measuring of conducted emissions (CE) are presented and discussed. FCC and CISPR standards are approached. A line impedance stabilization network (LISN) must be inserted between the AC power cord of the device under test and the commercial power outlet. Due to the difference in the regulated frequency ranges between the FCC and CISPR 22 Standards, the LISNs for both of them have similar layouts, but the component values are different. Standards used for test setup CE measurements are presented to understand the test procedures used to measure CE. Test instruments used for measuring CE are presented. A laptop was selected as the equipment under test (EUT). It is basically a noisy source containing a switched mode power supply. The standard requirements for CE and configuration of the test set-up measurements were investigated in this case. Also the test instruments used for accurate measurements and suitable comparison to the limits provided in the required standards are discussed. The equipment used for the measurements were: a LISN, a measuring EMI receiver and specialized software – EMC32. In fact the conducted disturbance voltages were measured by using the methods required by CISPR 22, that was applied considering the frequency range from 150 kHz to 30 MHz. The results for the CE measurement are presented. The quasi-peak and average values during testing do not exceed the allowed limits and comply with the standard required. The tests revealed that the values obtained with the EMC32 software comply with the standards, therefore the equipment tested can be validated. |
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