MIL-PRF-55629E
4.8.7.2 Actuator operating force (lever type) (see 3.11.2). The force necessary to operate the actuator shall be
applied in both directions at the tip of the lever. The force shall be applied normally to the lever axis and in the plane
of lever travel. The magnitude of the operating forces shall be measured to determine compliance with 3.11.2.
4.8.8 High-temperature and low-temperature operation (see 3.12) (when specified (see 3.1)). Circuit breakers
shall be conditioned for 2 hours at -40șC ±2șC at which temperature the calibration test shall be performed in
accordance with 4.8.5.2 plus an additional test at the 100-percent level. During these tests the auxiliary contacts
shall be monitored for proper operation. While still maintained at the -40șC low temperature extreme, the insulation
resistance test shall be performed in accordance with 4.8.4. Circuit breakers shall then be conditioned for 2 hours at
85șC ±2șC at which temperature the calibration test shall be performed in accordance with 4.8.5.2, plus an additional
test at the 100-percent level. During these tests the auxiliary contacts shall be monitored for proper operation. While
still maintained at the 85șC high temperature extreme, the dielectric withstanding voltage and insulation resistance
tests shall be performed in accordance with 4.8.3 and 4.8.4, respectively. Circuit breakers shall be examined for
evidence of mechanical damage.
4.8.9 Endurance (see 3.13). Unless otherwise specified (see 3.1), circuit breakers shall be subjected to 10,000
mechanically performed make and break operations; (6,000 operations with the circuit breaker energized at rated
current, voltage, and frequency (see 3.1) and 4,000 operations without power), at a rate not to exceed six operations
per minute. Half of the sample units shall be tested with the specified inductive load and half with the specified
resistive load (see 4.8.9.1). Each pole of multipole breakers shall be simultaneously subjected to the required load.
(Voltage sensitive poles (see 3.1) shall be subjected to 33 electrical operations at the maximum operating voltage for
each frequency.) The rate of operation shall not exceed one operation per minute. Wiring connections shall be in
accordance with figure 2. When applicable, the auxiliary contacts shall also make and break the maximum rated 60
Hz voltage and current (see 3.1). Except for voltage sensitive poles, an operating cycle is defined as the mechanical
closing and opening of the breaker, and the ratio of "on" time to "off" time shall be less than 1 to 5. The mechanical
operation shall simulate manual operation of the breaker, including overtravel, if any (see 6.6.4). All metal parts of
the circuit breaker outside the normal mounting panel shall be connected through a circuit breaker or a normal slow
blow fuse as shown on figure 2. Their rating shall be 5 percent of the test load or 100 mA, whichever is greater.
Where the polarity of the breaker is not specified, the power source shall be connected to one side of the breaker for
half of the operations and to the other side of the breaker for the remaining operations. The grounding fuse of circuit
breaker shall be observed during the test to determine if failure occurs prior to conclusion of the test. Circuit breakers
shall be examined for evidence of mechanical damage or loosening of parts. Following the test, circuit breakers shall
be subjected to the following tests:
Dielectric withstanding voltage (see 4.8.3).
a.
b.
Insulation resistance (see 4.8.4).
Calibration (see 4.8.5.2).
c.
d.
Resistance or impedance (see 4.8.6).
4.8.9.1 Loads. For ac inductive loads, the power factor shall be 0.75 to 0.80. For ac resistive loads, the power
factor shall be between 0.90 and unity. For dc inductive loads, the time constant (L/R ratio) shall be 0.02 to 0.03.
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