MIL-PRF-39019F
4.8.4 Insulation resistance (see 3.7). Circuit breakers shall be tested in accordance with method 302 of
MIL-STD-202. The following details shall apply.
a.
Test condition: A.
b.
Point of measurement:
(1) Between all main circuit breaker terminals tied together and actuating lever and case tied together, with
circuit breaker main contacts in closed and open positions.
(2) Between all auxiliary contact terminals tied together and main circuit breaker terminals tied together, with
circuit breaker main contacts in closed and open positions.
(3) Between poles of multiple pole breakers with the line terminal of each pole tied to the corresponding load
terminal of that pole, with circuit breaker main contacts in closed and open positions.
(4) Between all auxiliary contact terminals tied together and actuating lever and case tied together, with circuit
breaker main contacts in closed and open positions.
(5) Between each open pair of auxiliary contact terminals, with circuit breaker main contacts in closed and
open positions.
(6) Optional points of application: When test is specified to all main circuit breaker terminals tied together, the
test may be applied to individual poles.
4.8.5 Resistance or impedance (see 3.8). Circuit breakers shall be tested as follows:
a.
Main contacts: Samples shall be divided as evenly as possible (with respect to current rating) into three
groups for testing at dc, 60 Hz, and 400 Hz. With the circuit breakers mounted in their normal vertical position,
the resistance or impedance shall be measured between main terminals of each pole at 100 percent rated
current, and applicable frequency (see 3.1), using the voltmeter-ammeter method. These measurements shall
be made and recorded after the circuit breaker has been subjected to these conditions for 1 hour.
b.
Auxiliary contacts: Auxiliary contact resistance shall be measured using the voltmeter-ammeter method using
a 20 V ac or dc source with limiting resistance to 0.5 ampere. The initial measurement shall be made in the
"as received" condition.
4.8.6 Calibration (see 3.9).
4.8.6.1 Method I (used for qualification inspection).
4.8.6.1.1 Time delay A and time delay B. Circuit breakers shall be mounted by their normal mounting means and
tested in the vertical mounting position. Circuit breakers shall be connected as shown on figure 2 and conditioned for
1 hour at 100 percent of rated current, rated voltage, and rated frequency. Tripping times shall then be measured
when circuit breakers are subjected to the following percentages of applied rated current applied as a step function:
100, 135, 200, 400, 600, and 800. The sample units shall be divided as evenly as possible (with respect to current
rating and time delay) into three groups for testing at the following voltages and frequencies: 50 V dc, 240 V ac at 60
Hz, and 240 V ac at 400 Hz. There shall be sufficient time (not less than 10 minutes) between each application of
current to permit proper cooling of the circuit breaker. Circuit breakers rated for high inrush shall also be mounted in
three mutually perpendicular directions and while mounted in each position shall be subjected to a half wave of a 60
Hz waveform the peak value of which is 800 percent of the rms and DC rated load current and a half wave of a 60Hz
or 400 Hz waveform the peak value of which is 1400 percent of the rms and DC rated load current. Normally tests
shall be conducted within the rated operating voltage. However, if the inherent resistance or impedance of the circuit
breaker precludes attainment of the required percentages of overload current at the rated operating voltage, for the
purpose of determining tripping times and high inrush capabilities, the voltage shall be increased as necessary, up to
a maximum of 40 percent. If the specified overload current cannot be obtained with a maximum increase in voltage
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