MIL-STD-1399-300 Electric Power, Alternating CurrentThis military standard section establishes electrical interface characteristics for shipboard equipment utilizing AC electric power to ensure compatibility between user equipment and the electric power system. Characteristics of the electric power system are defined and tolerances are established, as well as requirements and test methods for ensuring compatibility of shipboard user equipment with the power system. The policies and procedures established by MIL-STD-1399 are mandatory. This section and the basic standard are to be viewed as an integral single document for use in the design and testing of electric power systems and user equipment.

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MIL-STD-1399-3008

5.1.6.2.2  Type III, 400 Hz power transient voltage.  Figure 14 illustrates the 440 Vrms, Type III, 400 Hz worst case voltage excursion and user voltage tolerance envelope specified in Table I.  Figure 15 illustrates the 115 Vrms,

400 Hz, worst case voltage excursion and user voltage tolerance envelope as specified in Table I.  Voltage transients of 5 percent or less may occur several times an hour.  The time to reach the transient maximum may vary from 0.001

to 0.1 seconds.  The sudden application of user equipment to the Type III, 400 Hz electric power system may cause

the voltage to decrease to the transient voltage minimum within 0.001 to 0.1 seconds.  The voltage may then increase to a maximum value that is above the nominal voltage by an amount equal to ⅓ to ⅔ of the minimum transient voltage drop at a rate equal to 50 to 100 percent of the nominal voltage per second.  Recovery to within the user voltage tolerance envelope will occur within 0.25 seconds.  The sudden removal of user equipment from the Type III, 400 Hz electric power system may cause the voltage to increase to the transient voltage maximum within

0.001 to 0.1 seconds.  The voltage may then decrease to a minimum value that is below the nominal voltage by an amount equal to ⅓ to ⅔ of the maximum transient voltage rise at a rate equal to 50 to 100 percent of nominal voltage

per second.  Recovery to within the user voltage tolerance envelope will occur within 0.25 seconds.

FIGURE 14.  Type III, 440 Vrms, 400 Hz power - worst case and user voltage tolerance envelopes.

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