MIL-DTL-17587C(SH)
4.5.8.4.2 Anti-rolling verification. Testing shall be conducted in accordance with 4.5.5.1.3.2 except that the 25-
pound force shall not be applied.
4.5.9 Temperature rise.
4.5.9.1 Circuit breaker temperature rise at rated current (pre-interruption and post-interruption).
4.5.9.1.1 Test circuit. At room ambient, circuit breakers shall be operated in their specified enclosures at any
convenient voltage and maximum rated continuous current on all main contacts and overcurrent coils. If no
enclosures are specified, test enclosures simulating the minimum volume compartment of a MIL-DTL-16036
standardized switchgear unit shall be used. Circuit breaker enclosures shall be protected from drafts and from
abnormal heat convection by a shield, if necessary. Copper bus bars shall be used for connecting to the top studs,
and cable shall be used for connecting to the bottom studs. Size of the bus bar and cable shall be as specified in the
applicable specification sheet. The copper cross-section of leads shall remain constant for at least 3 feet from each
stud on the circuit breaker.
4.5.9.1.2 Sensor locations.
4.5.9.1.2.1 Ambient. The ambient temperature shall be determined by two temperature sensors (thermometers,
thermocouples, or other approved method). The sensors shall be located within two feet of each side of the circuit
breaker at half the depth and half the height of the circuit breaker.
4.5.9.1.2.2 Circuit breaker and cradle. Temperature rise shall be measured at the hottest point where the
following current-carrying parts are in touch with the insulating material:
a. Circuit breaker line and load side terminals on each phase.
b. Cradle line and load terminals on each phase.
c. Circuit breaker main contacts on each phase.
d. Conducting mechanical joints on each phase.
4.5.9.1.3 Temperature stabilization and temperature rise determination. All temperature readings shall be
recorded during the same time frame and shall be of sufficient duration to allow stabilization of the measured
temperatures to a rate of rise within 2 °C per hour. Ambient temperature shall be maintained at room temperature
±5 °C. An average ambient temperature shall be determined by averaging together the ambient sensor readings.
The average ambient temperature shall be used to determine the temperature rise of monitoring points specified in
4.5.9.1.4 Pass/fail criteria. Temperature rise shall not exceed the limits as specified in Table I.
4.5.9.2 Temperature rise above rated current. Immediately following the temperature rise test at rated
continuous current, an additional test of 5 minutes duration shall be conducted with the current increased to 150
percent on all main contacts and spare auxiliary contacts. At the end of this test, the temperature rise of the hottest
terminal and mechanical conducting joint shall not exceed the applicable values in Table I.
4.5.9.3 Attachment temperature rise.
4.5.9.3.1 Electric closing device and shunt trip. Temperature rise of electric closing device and shunt trip shall
be measured during electrical endurance testing while the attachments are used to cycle the circuit breaker. Sensors
shall be located on the housing of the electric closing device and shunt trip to determine the temperature rise. The
temperature rise shall not exceed the pre-interruption (rated current) limits for insulation as specified in Table I.
4.5.9.3.2 Undervoltage release device, auxiliary contacts, and secondary disconnecting device contacts. During
electrical endurance testing, a sensor shall be located on insulation material nearest to the "a" auxiliary contact used
as the shunt trip cut-off switch. The temperature rise shall not exceed the pre-interruption (rated current) limits for
insulation as specified in Table I. During pre-interruption and post-interruption temperature rise testing at rated
current, sensors shall be located on the housing of the undervoltage release device and the insulation material nearest
to an "a" auxiliary contact and an associated secondary disconnecting contact. The temperature rise shall not exceed
the pre-interruption (rated current) limits for insulation as specified in Table I.
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