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-1399-3OO8

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Line-to-line voltage tolerance (percent) = 1 Line - to - line voltage  -   Nominal user voltage 1x1OO

Where:

⎝               Nominaluser voltage                    ⎠

The line-to-line voltage is each line-to-line voltage and the nominal user voltage is provided in

Table I, item 7.

EQUATION 3

3.4.3  Voltage unbalance (line-to-line).  The line-to-line voltage unbalance is the maximum deviation of any of the three line-to-line voltages from the average voltage divided by the average voltage.  Voltages are either all rms or all peak (sinusoidal crest) values as shown in Equation 4.

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Line-to-line voltage unbalance (percent) = 1 Maximum deviation from the average voltage1x1OO

Where:

⎝                  Averagevoltage                       ⎠

The average voltage is the sum of the line-to-line voltages divided by the number of line-to-line voltages.

EQUATION 4

3.4.4  Voltage modulation (amplitude).  Voltage modulation is the periodic voltage variation (peak-to-valley) of a single line-to-line user voltage, calculated by Equation 5 and shown in Figure 3.  The periodicity of voltage modulation should be considered to be longer than 1 cycle time at nominal frequency and less than 1O seconds. Voltages used in the following equation are either all rms or all peak (sinusoidal crest) values.  Vnominal  is provided in Table I, item 7.

V maximum   - V minimum        

Voltage modulation (percent) =  1                        1 x1OO

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⎝     2 x Vnominal              ⎠

EQUATION 5

FIGURE 3.  Voltage amplitude modulation.

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