MIL-DTL-17060G(SH)
4.6.17.1 Measurement of test voltage. The measurement of the voltage used in dielectric tests shall be made by
the voltmeter method whereby the instrument derives its voltage from the high-volt circuit either directly or by
means of a voltmeter coil placed in the testing transformer, or through an auxiliary ratio transformer. In any case, if
the capacitance of the machine to be tested is such as to cause wave distortion, the testing voltage shall be checked
by a crest-voltage meter. If the crest-voltage meter is calibrated in crest volts, its reading shall be reduced to the
corresponding rms sinusoidal value by multiplying by 0.707.
4.6.17.2 Points of application. Test voltage shall be successively applied between each electric circuit and all
other electric circuits and metal parts grounded. Test voltage shall be applied in such a manner as to preclude the
possibility of pitting the bearings in case of insulation failure. Voltage need not be applied between stationary and
rotating windings.
4.6.18 Electrical balance. Line currents measured during the heat run test of 4.6.16 shall be used to
demonstrate conformance to the electrical balance requirement of 3.6.13.
4.6.19 Sealed insulation system.
4.6.19.1 Sealed insulation system certification. Prior to motor delivery, certification of the sealed insulation
system shall be demonstrated by the manufacturer through certification in accordance with MIL-STD-2037. Upon
demonstration of compliance with MIL-STD-2037, NAVSEA will issue a letter of certification. This letter shall be
evidence of certification for motors with a sealed insulation system.
4.6.19.2 Sealed insulation system - electrical. Sealed insulation systems shall be tested as follows:
a. Insulation resistance (submergence). Each wound assembly including lead connections shall be submerged
for 24 hours in fresh water with a minimum conductivity of 500 microsiemens/cm and a maximum surface tension
of 31 dynes/cm at 77 °F (25 °C). Wound assemblies with commutators or slip rings should be submerged to a point
where the water level is as close as possible to the uninsulated areas.
(1) The conductivity of the fresh water may be increased by adding bicarbonate of soda to the water (salts
are not used due to corrosive effects). The surface tension may be adjusted by addition of a wetting agent such as
Triton X-100 (manufactured by Rohm and Haas, Philadelphia, PA) or equivalent.
(2) The dry insulation resistance should be verified to be not less than 1000 megohms prior to
submergence. While submerged, as a minimum, the insulation resistance shall be measured after 1 minute, 10
minutes, 1 hour, and 24 hours. Insulation resistance shall also be measured immediately after removal from
submergence, and one hour after removal from submergence. Values of insulation resistance shall be corrected to
77 °F (25 °C) and shall be in accordance with 3.5.1.31. Insulation resistance shall be measured using a 500 Vdc
potential between the windings and ground.
b. Insulation resistance (dry). Apply a test potential of 500 Vdc between the windings and ground until a
stable reading is obtained, but not less than 1 minute. Measure the insulation resistance and the average winding
temperature. If the winding is at ambient temperature, a measurement of the ambient temperature may be
substituted for that of the winding temperature. A megohm bridge or meter shall be used with a range of 0.1 to
1,000,000 megohms. Insulation resistance measurements shall be corrected to 77 °F (25 °C) and shall be as
specified in 3.5.1.31.
c. Surge comparison. A commercial surge comparison tester with a minimum operating voltage range of 0 to
5,000 volts shall be used. The comparison tester shall be connected to the stator windings in and the test voltage
shall be adjusted to 5,000 volts in accordance with the facilities procedure approved in accordance with
MIL-STD-2037.
4.6.20 Efficiency. The efficiency test shall be conducted as specified in Appendix C.
4.6.20.1 Efficiency testing for VSD motors. Efficiency testing for VSD motors shall be conducted per 4.6.20
at base speed (see 6.6.25.6). The horsepower test point is the horsepower requirement at base speed (see 6.2).
4.6.21 Preload device. This test is applicable to submarine motors with special preload requirements (see 6.2).
The uncompressed length of the preload device shall be measured before and after being fully compressed. The
force required to compress the preload device shall be measured for the nominal design value of compression
associated with the preload device's intended application.
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