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

5.3.1.1  Apparatus.  The following apparatus is recommended for performing this test:

a.    Power source of required capacity and range of voltage and frequency adjustments.  A power source with a capability of having an independently programmable voltage and frequency output is recommended.

b.    Voltmeters (true rms) - ±0.5 percent accuracy. c.    Frequency meter - ±0.5 Hz accuracy.

d.    Temperature meter - ±0.5 °C accuracy.

5.3.1.2  Procedure.  The user equipment shall first be operated in a normal operating mode within the steady- state voltage and frequency tolerance envelopes as identified in Figures 9 through 15 until the equipment temperature has stabi1ized.  Temperature stability shall be defined as when the variation between successive temperature measurements at the same location does not exceed 1 °C after 30 minutes.  The user equipment shall then be subjected to the limits of the user voltage and frequency tolerance envelopes of Table II.  Set the following combinations:

a.    voltage upper limit and frequency upper limit b.    voltage upper limit and frequency lower limit c.    voltage lower limit and frequency lower limit d.    voltage lower limit and frequency upper limit

The user equipment shall be operated at each combination until its temperature has stabilized and for 30 minutes thereafter.  This test shall be repeated for each mode of equipment operation.  Voltage, frequency, and internal equipment temperatures shall be measured and recorded at 10-minute intervals.  During and after testing, equipment shall operate normally with a stable temperature and with no operational degradation to show compliance with this test.

5.3.2  Voltage and frequency transient tolerance and recovery test.  The user equipment performance shall be evaluated under the transient frequency and voltage conditions (from nominal) specified in Table III.  Frequency testing can be accomplished on a component basis in lieu of larger modules or complete unit testing.

TA8LE III.  Transient voltage and frequency tolerance and recovery test.

5.3.2.1  Apparatus.  The following apparatus is recommended for performing this test:

a.    Power source of required capacity and range of voltage and frequency adjustments.  A power source with a capability of having an independently programmable voltage and frequency output is recommended.

b.    Voltmeters (true rms) - ±0.5 percent accuracy. c.    Frequency meter - ±0.5 Hz accuracy.

d.    Storage oscilloscope having � 500 kHz response per channel.

e.    Current and potential transformers and probes as required. f.     Temperature meter - ±0.5 °C accuracy.

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