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

3.4.5 Voltage transients. A voltage transient (excluding voltage spikes) is a sudden change in voltage that goes outside the user voltage tolerance limits and returns to and remains within these limits within a specified recovery time (longer than 1 ms) after the initiation of the disturbance.

3.4.5.1 Voltage transient tolerance. Voltage transient tolerance is the maximum permitted departure from nominal user voltage during transient conditions. The voltage transient tolerance is in addition to the user voltage tolerance limits.

3.4.5.2 Voltage transient recovery time. Voltage transient recovery time is the time elapsed from the instant when the voltage first goes outside the user voltage tolerance limit until the instant when the voltage recovers and remains within the user voltage tolerance limit. This is shown in Figure 4.

Recovery Time

Peak Transient Voltage

Voltage Transient Tolerance Limit

User Voltage Tolerance Limit

TIME

Peak Transient Voltage

User Voltage Tolerance Limit

Voltage Transient Tolerance Limit

FIGURE 4. Voltage transient tolerance.

3.4.6 Voltage spike. A voltage spike is a voltage change or impulse of very short duration (less than 1 ms) represented in Figure 5. Voltage spikes in shipboard power systems are generally of an oscillatory nature and not unidirectional as those often used in testing. The impulse waveform shown in Figure 6 is the characteristic voltage spike used for test purposes.