IEC 60255-22-1 forms part of the IEC 60255-22 disturbance series and specifies the immunity test in which a 1 MHz damped oscillatory burst is applied to measuring relays and protection equipment. The test reproduces the burst-type disturbance that appears on station wiring when disconnectors, circuit breakers and contactors operate, a phenomenon that is more repetitive and better damped than the single transients covered by the surge and fast-transient tests. The standard states the generator output characteristics, the burst duration and repetition rate, the common-mode coupling network through which the disturbance reaches the equipment, and the severity classes from which the applicable level is selected. It also defines the test configuration, including the reference earth and the arrangement of the cables connecting the equipment, so that results from different laboratories can be compared. Performance is judged against the functional criteria declared for the protection function under test. The current part numbering replaces the older IEC 255-22-1 designation, although the technical content is closely related.