MIL-DTL-2212K(SH)
c.
The ambient temperature in the testing area shall vary not more than 18 °F (10 °C) during tests.
4.6.1.1 Reduced voltage controllers. Starting autotransformers, reactors, and resistors shall be tested to
determine conformance to temperature rise limits specified in NEMA ICS 2.
4.6.2 Endurance. Endurance tests shall be conducted between 10 and 20 operating cycles per minute, except
tests making and breaking 600 to 400 percent of rated current shall be conducted at 6 operating cycles per minute
(closed 1 second, open 9 seconds). Tests making and breaking 600 to 400 percent of rated current, and where
practical all other tests, shall be performed continuously without interruption. Tests breaking 100 percent rated
current may be stopped and restarted for convenience provided each operational test period lasts a minimum of
6 hours. Mechanical operational tests may be stopped and restarted as necessary. Mechanical operational tests are
not required for solid-state devices. A malfunction causing shutdown or out of specified limit performance during
this period shall constitute a failure requiring corrective action. A failure has not occurred if malfunction can be
attributed to external causes such as ambient temperature over the specified temperature, variation of input power
parameters beyond specified limits, operator's error, and other unusual conditions. Equipment shall meet the
requirements specified in 3.15. If a failure occurs during the run, the cause shall be determined and correction(s)
made.
4.6.2.1 Restarting endurance test. Upon completion of corrective action after malfunction, the equipment shall
be restarted from the first operation.
4.6.2.1.1 Termination of endurance run. In the event that an endurance run is incomplete after more than three
failures have occurred during the test, the test shall not be continued unless approved by the contracting activity.
4.6.3 Overload protection. Overload relays shall be tested for tripping characteristics (see 4.6.3.1). Resetting
time and temperature compensation shall be as specified in 3.16.5.
4.6.3.1 Tripping characteristics. Overload relays shall be tested in a 122 °F (50 °C) ambient temperature at
110, 125, 150, 300, and 500 percent of rated current to determine that the tripping characteristic falls within the
acceptable band shown on figure 1. Tests may be conducted at room ambient temperature if the appropriate
temperature compensation correction factor for the deviation from specified ambient temperature (see 3.16.6.1h) is
applied as specified in 3.12. Relays shall be tested using the lowest, the highest, and a median rated heater or coil.
4.6.3.2 Special temperature sensing circuitry. Special circuitry for direct temperature sensing and protection of
the controlled device shall be tested throughout its operating range with a sensor similar to that used in the protected
device.
4.6.4 Vibration. Before vibration testing, an examination and general operation test shall be performed. The
equipment shall then be subjected to the Type I vibration tests as specified in MIL-STD-167-1 for conformance to
3.17.2. Equipment shall be operated at nominal voltage and frequency during the tests and mounted in a fashion to
simulate shipboard conditions, including sway bracing when required. During the variable frequency tests the
equipment shall be operated in normal operational modes to verify that all features and devices are functioning
correctly. During the endurance tests, the operational checks will be performed at 60-minute intervals. External
devices shall be simulated as necessary to perform the operational checks. Specific electrical loads are not required,
but at least one set of each type of contact on every device shall be monitored by suitable means (voltage recorder,
ohmmeter, indicator light, and so forth) to check the opening and closing performance. When testing individual
devices, each set of contacts shall be monitored. For electronically-based control circuit devices and associated
switching devices, vibration testes shall be conducted with all inputs and outputs operating or powered and
monitored to ensure they do not change state. After the vibration test, an examination and general operation test
shall verify performance.
4.6.4.1 Time delay relays. Time delay relays shall be adjusted to any convenient setpoint for vibration testing.
Performance shall conform to 3.17.2.2. Post-test reference measurements shall verify that the set time delay has not
changed and that setpoint repeatability and variation of the indicated time delay conform to 3.16.4.3.
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