MIL-STD-1399-3008
5.3.4.2.3 Power source decay test. Following the power system interruption tests, the power source shall be modified as required to provide a voltage and frequency decay characteristic approximating that shown on Figure 8 for the "Half-load on Generator" curve. With the user equipment operating in one of the normal operating modes and with the power input voltage and frequency at nominal, initiate the power source output voltage and frequency decay characteristics specified above. The voltage and frequency shall follow the decay curves provided in Figure 8 extrapolated down to zero. If the test equipment source frequency does not extend down to zero, lower the frequency to the 50-percent value or lower and de-energize the test equipment source. At the end of the voltage and
frequency decay transient, the power source output shall immediately return to nominal voltage and frequency. Line voltage, line current, and frequency shall be measured and recorded before the initiation of and during the power source decay test. The user equipment is not required to sustain operation during this test after the voltage and
frequency go below the worst case envelopes as defined in Figures 9, 12, and 13. However, the unit shall be capable
of returning to normal operation after power is suddenly re-applied at the end of the decay transient. Repeat the power source decay test for each operating mode.
5.3.4.2.4 Positive excursion test. Upon completion of the power source decay test, the user equipment shall be subjected to the emergency condition positive excursion tolerances specified in Table I, items 19 through 22, and duplicated in Table VI. The user equipment shall be operated in a normal mode with the power input voltage and frequency at nominal. The power input voltage shall be varied from nominal in accordance with the positive excursion limits and time duration specified in Table VI. At the end of the excursion duration, the power input voltage shall be immediately returned to nominal voltage. Then the power input frequency shall be varied from nominal in accordance with the positive excursion limits and time duration specified in Table VI. At the end of the excursion duration, the power input frequency shall be immediately returned to nominal frequency. Finally, the power input voltage and frequency shall be varied simultaneously from nominal in accordance with the positive excursion limits and time duration specified in Table VI. At the end of the excursion duration, the power input voltage and frequency shall be immediately returned to nominal voltage and frequency. Line voltage, one line current and frequency shall be measured and recorded before, during, and after each positive excursion test. Repeat the positive excursion test for each operating mode of the user equipment under test. Unless specified as Mission Critical Equipment (MCE) by the PDA and thereby required to operate through this test, the user equipment is not required to sustain operation during this test after the voltage and frequency go above the worst case envelopes as defined in Figures 9 through 15. However, the unit shall not be damaged and shall be capable of returning to normal operation when power is restored within the user tolerance envelope. MCE shall remain operational before, during, and after this test; the user equipment under test shall not experience any damage or operational interruption, suffer any loss of data, or require a restart or reboot.
TA8LE VI. Emergency condition test.
Emergency Condition |
Voltage Tolerance Percent of Nominal |
Frequency Tolerance Percent of Nominal |
Maximum Excursion: Duration - Type I power systems Duration - Type II power systems Duration - Type III power systems |
+35 2 minutes 0.17 seconds 0.17 seconds |
+12 2 minutes 0.17 seconds 0.17 seconds |
5.3.5 Grounding test. For ungrounded systems, user equipment shall be tested for proper operation in each operating mode with one power input line grounded.
5.3.5.1 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. Voltmeter (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.
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