MIL-PRF-11021H
Where:
I = Effective current in amperes.
i = Demand current in amperes.
t = Accumulated circuit breaker conduction time (last five cycles only).
T = Total on time (last five cycles only).
4.6.8 Overload test. To determine conformance to 3.4.8, the switch assembly shall be
connected as shown in Figure A3 and the circuit calibrated as specified in 4.6.6 to deliver 575 +
25 amperes. Each specified circuit (except the panel lamp dimming circuit) shall have the
overload current applied to it five times. The time between applications of the overload current is
the time needed by the switch assembly circuit breaker to reclose.
4.6.9 Circuit breaker resistance to short circuit. To determine conformance to 3.4.9, the
test specified in 4.6.8 shall be repeated, with 10 additional cycles for each of the tested circuits.
Permanent opening of the tested circuit during overload testing meets the requirements of 3.4.9.
Subsequent to the testing, the switch assembly shall be tested as specified in 4.6.3 except the
ambient air temperature shall be 80 + 5°F, the continuous current shall be at least 21.0 amperes,
and the ultimate trip current shall not exceed 32.0 amperes.
4.6.10 Circuit breaker endurance test. To determine conformance to 3.4.10, the switch
assembly shall be connected in the circuit shown in Figure A3, and the current set to a minimum
of 40 amperes for 2000 cycles as specified in 4.6.6. The values selected for R1, R2, and L1 shall
be such that:
R1 + RL1 = R2 + [L1 / (R1 + RL1)] = 0.026
Where:
R1, R2 = Variable resistances.
RL1 = Resistance of coil L1.
L1 = Inductance of coil L1.
0.026 = Time constant.
Calculation of the time constant involves taking the numeric values of the inductance in
Henries (H) and the resistance in ohms (Ω) and performing the indicated arithmetic operations.
Tolerances:
L1: -20% to +50%
R1 + RL1: = 10% of R2
(R1 + RL1 +R2) / (R2[R1 + RL1]) = + 10%
The switch assembly shall then be tested as specified in 4.6.3 except the ambient air
temperature shall be 80 + 5°F, the continuous current shall be at least 21.0 amperes, and the
ultimate trip current shall not exceed 32.0 amperes.
14
For Parts Inquires call Parts Hangar, Inc (727) 493-0744
© Copyright 2015 Integrated Publishing, Inc.
A Service Disabled Veteran Owned Small Business