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

5.2.9.4 400 Hz user equipment less than 0.2 kVA. The operation of user equipment with power ratings < 0.2 kVA shall be current amplitude limited so that no individual harmonic line current or current of any frequency above the fundamental at 400 Hz to 20 kHz shall exceed the limit line set at a magnitude of 40,000/f percent of the user equipment's full load fundamental current, where f is the frequency. This is shown in Figure 20.

Percent

of 400 Hz Fundamental Current (A)

FIGURE 20. Limit line for currents at frequencies greater than 400 Hz for equipment less than 0.2 kVA.

5.2.9.5 User equipment in the unacceptable range. When user equipment cannot meet the input current waveform limits specified in 5.2.9.1, 5.2.9.2, 5.2.9.3, or 5.2.9.4 a technical review of the outage shall be performed to determine its impact. Options that may be taken include a waiver, deviation, or electrical isolation.