Downloaded from https://www.everyspec.com MIL-STD-8iOD 19 July 1983 ,,?., Ac system normal“operation.stresses ~b’: Normal ON/OFF cycling of equipment operation .,,;,., c.“”;DC system normal “operationstresses ,,,,,..... . .,. . d.?.Electrical stresies induced by mission-related transients witbin the ,el,ect.ical, ”$ystem. I-3.2”.2,~,g’. 1 A’Csvstem normal ODera ~. . Voltage variations are quasi-steady changes in voltage f~om test cycle to test cycle. Input voltage? shall be maintained at 110 percent of nominal,for the first test cycle, at the nominal for the ?eccnd test cycle, and at 90 percent for the third test cycle.
This cycling procedure is to be repeated continuously throughout the ,test. However, if a failure ia suspected, this sequence may be interrupted for repetition of ‘input,voltageconditions. . . .-. . I-3.2.2.9.2 1 ON/OFF cvc mu of em ~. ment ooer-. The equipment shall be turned on.and,off, in accordance with equipment operating prcceduree outlined in “appropriatetechnical manuals, to SiMUlat6 normal Use. 1-3..2:?..9 ,.3 12$AVstem nmma i ODeratioi stress=. Voltage.variatim. See I-3.2.2.9.1 b,. Ripple voltage. Ripple is the cyclic variation about the mean “level of,the,DC voltage during steady-state DC electric system operation.
Values ‘shallbe taken from actual flight data or frDm the applicable sy?tem ‘specifi- cation if flight data are”not available. Ripple voltage “shallbe applied continuously during the missicn simulation porticn.of each test cYCle. I-3:2.2~9.4 Electrical stresses induced bv~ ion-related transiente witu ~m Unless the equipment has its cwn power supPly which is not affected by,the t~ansients mentioned, or the equipment is nOt influenced by these electrical stresses ,atall, these stresses must be reproduced during test. The reproduction hae to covek all transients --’like power surges, voltage peaks, electrical current changes, phase unbalance, etc.
-- which may influence the equipment on test and are induced by the mission-related operation,of the airCraft*s electrical/electronicequipment taken as a WhDle (switching eqUipIDent on or off, operating with changing power output, short-time system overload, differing gerie,ratorrpm, operation of regulating devicesj etc.),~’” Tbe test should reproduce measured transients exact1y. If this is not possible, tolerances should be calculated individually for.each transient type. Tolerances should be narrow for stresses the equipment is more sensitive tD, and vice versa.
The baais for calculations shall be the requirements’document stress values that the equipment must be able to withstand during normal operation’---provided the actual measured stresses of the electrical system do not exceed these limits. In the absence of any other means of simulating power line transienta, the equipment shall be cycled on while performance measurements are made ‘and then backed Dff for five minutes prior to the normal turn-cm at the end of each ground park phase. MRTHOD 520.0 520.0-15 19 July-1983