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Pull-up, breakdown, and locked-rotor torque. |
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|  MIL-M-17059A(SHIPS)
bearings of the driven auxiliary, this test may be conducted with the motor driving the unloaded auxiliary. Read-
ings of line volts and amperes, watts input and r.p.m. shall be taken and recorded. The motor shall be run for
a sufficient period of time to allow bearing losses to become constant before any readings are taken.
4.3.4.8 Pull-up, breakdown, and locked-rotor torque. - Readings of line volts and torque (plus amperes and
watts for locked-rotor) shall be taken and recorded for each of the above torques.
tests. -
4.3.4.9 Dielectric
4.3.4.9.1 General. - The dielectric test shall be made after all other tests have been complete. The
frequency of the testing voltage shall be not less than 60 cycles and shall approximate a sine wave. If the
insulation resistance of the windings is known to be lower than specified, due to dirt or moisture or damage
to windings, this shall be remedied before the application of the dielectric test voltage. The dielectric test
shall be made on the completely assembled machine and not upon individual parts. An exception is made in
the case of repair parts which require dielectric tests; for example, repair coils and repair rotating elements
with insulated windings. In the case of motors using capacitors, the dielectric test on the motor may be made
with the capacitor disconnected. The capacitor shall be given a separate dielectric test according to the rating
of the capacitor used.
4.3.4.9.2 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 trans-
former. 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 root-mean-square sinusoidal value by multiplying by
0.707.
4.3.4.9.3 Points of application. - The test voltage shall be successively applied between each electric
circuit and all other electric circuits and metal parts grounded. The 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.
4.3.4.10 Effectiveness of enclosure. - Motors shall be tested as specified in MIL-E-2036 except that
hose test of dripproof enclosures is waived.
4.3.4.11 Heat-run test. -
4.3.4.11.1 General. - The heat-run test shall be made on continuous duty motors in accordance with the
following:
Rated motor load - 100 percent.
Voltage - rated.
Time - until all temperatures are constant.
Motor load may be obtained by maintaining the current, torque or watts input corresponding to rated motor
hp. output.
4.3.4.11.2 Details of temperature test. -
4.3.4.11.2.1 Normal load heat runs on continuous-duty motors shall be continued until constant tempera-
tures have been attained in all parts of the motor. For motors having several continuous ratings, the heat run
shall be conducted using the rating giving the highest temperature rises. In cases where the highest tempera-
ture rises cannot be determined prior to the test, the motor shall be tested separately for each rating. Tem-
perature measurements by thermocouple shall be taken and recorded during the progress of the heat run to
determine when the constant operating temperature has been reached. It shall be considered that constant
temperatures have been reached when at least four consecutive readings taken at 15-minute intervals show
no increase in the temperature in any part of the motor. The resistance rise shall then be determined in
accordance with the procedures for method 2 of MIL-E-917.
4.3.4.11.2.2 The duration of temperature test of a motor with a short-time or overload requirement
shall be the time specified for that rating. Intermittent and varying duty motors shall be tested at the specified
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