MIL-DTL-17060G(SH)
4.6.16.1 Details of temperature tests. Normal load heat runs on continuous duty motors shall be continued
until constant temperatures 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 temperature rises cannot be determined prior to the test, the motor shall be tested separately for each rating.
Temperature measurements by thermocouple shall be used 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 three consecutive readings taken at 15-minute intervals show no increase in the temperature in
any part of the motor, when adjusted for changes in ambient temperature. The winding temperature rise shall then
be determined in accordance with the procedures for Method 2 of MIL-E-917. The bearings' temperature rise shall
be determined in accordance with the procedures of Methods 1 or 3 of MIL-E-917.
4.6.16.2 Duration of temperature test. The duration of the 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 duty cycle. In lieu thereof, the motors may be tested as short-time duty motors of sufficient rating to
meet the actual load requirements.
4.6.16.3 Use of temporary air filters. When temporary air filters are to be used, the tests of 4.6.16.1 shall be
repeated with the filter media specified (see 3.5.2.1.12) attached to the air intakes. Three thicknesses of filter media
shall be used to simulate a loaded or dirty filter. Temperature limits of table XIV shall apply.
4.6.16.4 Heat run measurements. The following measurements shall be made for each heat run test:
a.
Motor input voltage and current, watts and revolutions per minute.
b.
Motor output power (may be calculated using current, torque, or watt inputs).
c.
Temperatures measured concurrently as follows:
(1) Motor parts as required in table XIV
(2) Room ambient
4.6.16.5 Measurement of temperature rise. The temperature rise of each motor component part shall be
determined immediately at the conclusion of the heat run. Temperature rise (see table XIV) shall be determined in
accordance with Method 1 (thermometer), Method 2 (resistance), and Method 3 (embedded detector) of MIL-E-917.
In determining temperature rise, no correction shall be made for barometric pressure, humidity, or for any
differences in heat transfer characteristics between the test ambient temperature and the maximum design ambient
temperature.
4.6.16.6 Variable speed drive motor. Heat run testing for Variable Speed Drive (VSD) motors shall comply
with the following:
a. VSD motors meeting 3.5.2.8.2, driving pumps, fans, or compressors, shall be tested with a VSD. Testing
shall be performed at the maximum operating speed and at the horsepower rating associated with maximum
operating speed (see 6.2).
b. VSD motors for constant torque applications shall be tested with a VSD at the minimum operating speed at
the horsepower rating associated with minimum speed.
VSD motors meeting 3.6.11.5.4 shall be tested with the VSD at the specified duty cycle.
c.
4.6.17 Dielectric tests. The dielectric test shall be conducted after all other tests have been completed. The
frequency of the testing voltage shall be not less than 60 hertz 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 conducted on the
completely assembled machine and not upon individual parts. An exception is made in case of repair parts which
require dielectric test; 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 conducted with the capacitor disconnected. The
capacitor shall be given a separate dielectric test according to the rating of the capacitor used.
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