MIL-DTL-24640C
e. Conductor to conductor with component shield and one overall shield (or two or more overall shields not
electrically isolated from each other) (cable, shielded components, overall shielded, jacketed). Used for cable types
incorporating one or more individually shielded, insulated conductors: one insulated conductor shall be selected for
measurement, and shall be electrically connected to one terminal of the voltage source. All other insulated
conductors within the component and the shield shall be electrically connected to the other voltage source terminal.
The voltage withstand test shall then be performed as specified. Following this, and in an identical manner, the
voltage withstand test shall be performed on all remaining insulated conductors within the component. After the
completion of this component, this procedure shall be repeated for all other shielded components within the
specimen. The cable shall then be tested for component shield voltage withstand [see (h)].
f. Conductor to conductor with component shield and two electrically isolated overall shields (cable, shielded
components, overall dual shielded, jacketed). Used for cable types incorporating one or more individually shielded,
insulated conductors: one insulated conductor shall be selected for measurement, and shall be electrically connected
to one terminal of the voltage source. All other insulated conductors within the component and the shield shall be
electrically connected to the other voltage source terminal. The voltage withstand test shall then be performed as
specified. Following this, and in an identical manner, the voltage withstand test shall be performed on all remaining
insulated conductors within the component. After the completion of this component, this procedure shall be
repeated for all other shielded components within the specimen. The cable shall then be tested for component shield
voltage withstand, see h and overall shield voltage withstand [see (i)].
g. Component shield to shield. Used for cable types incorporating two or more individually shielded
components (these measurements shall be required only when component shield to shield measurements are
specified; see 3.1): one component shield shall be selected and electrically connected to one terminal of the voltage
source. All other specimen component shields shall be electrically connected to the other voltage source terminal,
and the voltage withstand test shall then be performed as specified. In a similar manner, the voltage withstand test
shall be performed between each remaining component shields within the specimen and the short circuited
combination of all other component shields.
h. Component shield to shield and overall shield. Used for cable types incorporating two or more individually
shielded components and an overall shield (these measurements shall be required only when component shield to
shield measurements are specified; see 3.1): one component shield shall be selected and electrically connected to
one terminal of the voltage source. All other specimen component shields and the overall shield shall be electrically
connected to the other voltage withstand terminal, and the voltage withstand test shall then be performed as
specified. In a similar manner, the voltage withstand test shall be performed between each remaining component
shields within the specimen and the short circuited combination of all other component shields.
i. Overall shield to shield. Used for cable types incorporating two or more overall shields (electrically
separate) (these measurements shall be required only when overall shield to overall shield measurements are
specified; see 3.1): the inner overall shield shall be selected and electrically connected to one terminal of the voltage
source. The other overall shield shall be electrically connected to the other voltage source terminal, and the voltage
withstand test shall then be performed as specified.
4.8.6.4 Observation. Specimen failure shall be construed if the voltage source overload relay trips prior to
removal of the test voltage from any specimen connection. If the insulation resistance test is specified (see 3.1),
then the specimen shall be retained for use in that test.
4.8.7 Jacket flaws. One hundred percent of all finished cables with overall shields shall be subjected to a 3.0
kV (rms) spark test in accordance with Clause 900 of UL Standard 1581.
4.8.8 Conductor and shield continuity. One hundred percent of all finished cable shall be tested for continuity
prior to shipment. To establish continuity, not more than 25 V DC shall be applied across each conductor and shield
of the cable through an appropriate indicator, such as an ohmmeter, light, or buzzer. The test voltage may be
applied to conductors and shields individually or in series.
4.8.8.1 Observation. Specimen failure shall be construed if the specimen exhibits an open electrical circuit.
4.8.9 Surface transfer impedance. The surface transfer impedance characteristics of the overall cable shield of
finished cable shall be tested in accordance with NEMA WC 61, and as specified in 4.8.9.1. The electromagnetic
pulse (EMP) response of the cable shield shall be determined in accordance with 4.8.9.2.
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