EMI hardening of “Flexi Nozzle Control system” — A case study

If the system consists of Electrical, Electronics and Electromechanical sub-systems, one can easily expect what sort of EMI can exists and how much it is difficult to control. Identification of problem becomes tough interms of noise contribution from different systems if they are on same dias. Most of the time, sub-systems will be tested with simulated load. EMI prediction is not an easy job for the system designer if the system fails with actual loads and actual sub-system´s configurations. Test setup arrangements also add or raise EMI levels, may be interms of cable lengths or degradation in the external grounding schemes or noise coupling through ground line. Estimating the situations, justifying the failures, eliminating the noise levels due to peripherals will lead into mismatch among different EMC analytical engineers. Initially, the Flexi Nozzle Control system was not able to give the output within the tolerance limit of ±100mV even at bench test due to the interference among the sub-systems. In this paper, the authors expressed their views about the practical problems faced and solved, also the analytical approach through which the noise segregation did and ensured each sub-system´s noise contributions. Ensured the normal operation of the system at bench, then each sub-system was tested using other sub-system as load through the interface unit. Achieved each sub-system´s EMC within the tolerance limit of ±100mV at bench test and in the presence of EMI Environment.