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

5.3.4 Emergency condition test. The emergency condition test shall be used to evaluate the user equipment performance under the following conditions:

a. Simulated automatic bus transfer test (70 msec power interruption and rapid re-application).

b. Simulated power interruption due to emergency power re-configuration test (2-minute power interruption and rapid re-application).

c. Simulated loss of steam to turbine generator (TG) test (power source voltage and frequency decay). d. Simulated loss of generator voltage regulation test (voltage and frequency positive excursion).

5.3.4.1 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 of reading. c. Frequency meter - ±0.5 Hz accuracy of reading.

d. Storage oscilloscope having > 500 kHz response per channel. e. Current and potential transformers and probes as required.

f. Frequency to voltage transducer.

g. Temperature meter - ±0.5 °C accuracy.

5.3.4.2 Procedure. The user equipment shall be operated in a normal operating mode and with the power input voltage and frequency within the user tolerance envelopes as shown on Figures 9 through 15, as applicable, until the equipment temperatures have stabilized. 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.

5.3.4.2.1 70 msec power interruption test. The input power at nominal voltage and frequency shall be suddenly interrupted. After an interval no less than 70 msec, the input power shall be suddenly reapplied to nominal voltage and frequency. This cycle shall be repeated in all operating modes. Power source frequency, line voltage (one- phase), and line current shall be measured at the user equipment power input terminals and recorded before the start and during each cycle. Equipment designated as mission critical equipment by the PDA shall operate through the interruption without loss of data or a requirement for a manual restart. Inrush current surges observed during power interruption tests shall be addressed as described in 5.2.10.

5.3.4.2.2 2-Minute power interruption test. After the equipment has been operated long enough to detect any performance degradation and with the equipment in normal operating mode, the power to the user equipment shall

be suddenly interrupted for an interval of 2 minutes followed by the sudden re-application of input power to the user equipment. This power interruption shall be accomplished by switching the power at the power source and not by

using the power switch or equivalent at the user equipment. No manual interaction shall be allowed until the power

is re-applied after the 2-minute interruption. This test shall be repeated in all operating modes. The user equipment is not required to sustain normal operation through the 2-minute power interruption; however, the unit shall be capable of returning to normal operation after power is suddenly re-applied at the end of the 2-minute interval. Inrush current surges observed during power interruption tests shall be addressed as described in 5.2.10.