MIL-STD-1399-3008
5.3.2.2 Procedure. The user equipment shall be operated in a normal operating mode within the user voltage and frequency tolerance envelopes as shown on Figures 9 through 15, as applicable, until the equipment temperatures have 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 input voltage and frequency shall then be simultaneously changed within 0.1 second to the applicable upper limit of Table III. Return the voltage and frequency to the user tolerance band within the applicable recovery time of Table I items 6 and 14. The initial condition of voltage, frequency, and line current shall be measured and recorded before the start of each test. Input voltages, frequency, and input line currents shall be recorded before initiation of the voltage and frequency transient and until the transient is completed. Repeat the test for the applicable lower limit of voltage and frequency given in Table III. Repeat the test for each normal mode of operation at the applicable upper and lower limits of transient voltage and frequency given in Table III. During and after testing, equipment shall operate normally with no operational degradation to show compliance with this test.
5.3.3 Voltage spike test. A voltage spike test shall be conducted to evaluate the capability of user equipment to withstand and operate before, during, and after the voltage spike as specified in Figure 6 (see 3.4.6). It is recommended the voltage spike be applied to the power leads at not more than 1.5 meters from the equipment input terminals. The test leads shall also be connected as close as possible to the input terminal of the user equipment.
5.3.3.1 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. The power source shall withstand the voltage spike test.
b. Voltage spike attenuation circuit - If necessary, to reduce the magnitude of the voltage spikes imposed on the power source during testing, between the power source and the test circuit, a metal oxide varistor (MOV) can be installed from each line-to-line connection from the power supply. The MOV shall be rated for the test to protect
the power supply. Also, it may be necessary to connect a one-microfarad capacitor across each set of MOVs to filter out the high frequencies present on the leading edge of the voltage spike generated by the spike generator. After the parallel MOV and capacitor circuit placed across each line-to-line terminal, between the power source and the test circuit, a series inductor shall be installed in each line to prevent attenuation of the spike presented to the Unit Under Test (UUT). The inductance should be as high as practicable without causing a voltage drop of such magnitude that the input voltage to the UUT is below the limit specified in this standard. The current drawn by the UUT will determine the maximum allowable inductor value. Appropriate damping resistors should be connected across each inductor to eliminate unwanted oscillations.
c. Solar Spike Generator, Model 7399-1 or 2 (modified to accept an independent 60 Hz sync input that is required if the input power source that is used for the spike generator is not synchronized with the unit under test input power source) or equivalent.
d. Oscilloscope with a minimum bandwidth of 30 megahertz (MHz) and a high voltage probe. e. Pearson wide-band current transformer or equivalent.
f. Rd (resistor, 1 ohm, 1 percent, 120 watt) voltage spike generator (VSG) output damping.
g. Cg (AC capacitors, 660 Vrms) to support the range 5 microfarad to 35 microfarad (typical: consisting of 5,
10, and 20-microfarad values).
h. Rs (two variable resistors: 0-1 ohm, 10 watt and 0-16 ohm, 50 watt, series connected). i. Lg (inductor, 5.7 mH, 370 Vrms, 2 Amps) used in power Types II and III testing.
j. Plug-in box, line-to-ground, SOLAR Part Number 739950 or equivalent.
k. Transformer (440 Vrms to 115 Vrms, 50 VA) used for conditioning the Sync Input when conducting 440
Vrms voltage spike tests.
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