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

5.2.9.3  400 Hz user equipment greater than or equal to 0.2 kVA.  The operation of user equipment or the aggregate with power ratings > 0.2 kVA shall not cause single harmonic line current or current of any frequency above the fundamental at 400 Hz to 13.33 kHz to be generated that are greater than the limit line set at 3 percent of the unit's full rated load fundamental current.  Additionally, harmonic line current or current of any frequency above

13,334 Hz through 20 kHz shall not exceed the limit line set at 40,000/f percent of the user equipment's full load fundamental current, where f is the frequency.  This is shown in Figure 19.  User equipment, for the purposes of this requirement, shall be defined as a system with a standalone unit or the aggregate of a system with multiple like units on a single bus, e.g. lighting source power supplies.  The rating of equipment with multiple power inputs from the same interface shall be the summation of all the power inputs under steady-state conditions.

Percent

of 400 Hz

Fundamental

Current (A)

FIGURE 19.  Limit line for currents at frequencies greater than 400 Hz for equipment greater than or equal to 0.2 kVA.

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