Optimum dwell time determination for RF immunity test

The EMC regulations call for a radio frequency immunity test for the majority of electronic equipment. The relevant IEC 1000-4 series standard specifies the maximum permitted rate of sweep and the step size to carry out the tests. The optimum choice of dwell time at sensitive frequencies is an important factor when conducting the RF immunity tests to ensure repeatability. Considering the complexity of arriving at an optimum dwell time for a wide variety of electronic equipment, the general tendency may be to carry out the test with the maximum sweep rate specified in the standard. The sweep rate and corresponding dwell time chosen must be compatible with the response time of the EUT and operational modes. The inadequacy of choosing an arbitrary dwell time is highlighted in this paper. The relevant details of a radiated immunity case study (power line carrier communication equipment) conducted using an experimental approach, to optimize the dwell time is presented. An analysis of arriving at a dwell time parameter at a typical sensitive frequency is included