Common mode current measurements and radiated emissions from long cable systems

Given the size and complexity of the installations which are being measured, currently applied standards are of limited value in assessing their performance. Common mode current measurements for emissions offer an acceptable solution to an otherwise difficult problem. The degree of equivalence between the results quoted suggest that these alternative methods may prove the basis for a standard in their own right which will alleviate many of the problems associated with the measurements of large distributed systems. The experimental uncertainty estimates show that common mode current measurements are in excellent agreement with the CISPR 22 type radiated measurements. These measurements only consider emissions on the system cabling and do not consider direct board radiation. The author concludes that the most effective test procedure would include the measurement of both radiated field and conducted common mode signals when determining the compliance of a system containing large lengths of cable