MIL-R-83407C
4.5.22 Life (see 3.25). Each sample relay shall be life tested for a minimum of 50 million operations. The following details apply:
a. Test temperature: Room temperature.
b. Mounting position: During the performance of all the tests specified herein, the relays shall be positioned, unless otherwise specified (see 3.1), with the long side of the header vertical and with the terminals horizontal and with the NO and NC terminals at the top.
c. Arc suppression: An external arc suppression circuit shall be electrically connected to each pair of contacts which make and break during the life test.
d. Energizing voltage: The rated voltage (see 3.1) shall be used to energize the coil.
e. Cycling rate: The cycling rate shall not be less than 40 Hz or more than 80 Hz. "On" and "off" periods shall be approximately equal.
f. Contact load: The contact load shall be one ampere resistive at an open circuit voltage of 100 V dc, unless otherwise specified (see 3.1). A load resistor shall be connected between each stationary contact and the positive terminal of the load power supply. The negative terminal of the load power supply shall be connected to the movable contact terminal. Unless otherwise specified (see 3.1), a contact protective circuit consisting of a 0.1 microfarad capacitor connected in series with a 10 ohm resistor shall be connected across each stationary contact and the respective movable contact. Connect the outer end of the resistor to the stationary contact terminal and the outer end of the capacitor to the respective movable
contact terminal. Keep the resistor and capacitor leads and the contact power leads as short as practicable. Route the contact power supply leads as far away from one another as practicable to minimize lead capacitance.
g. Contact monitoring: The contacts shall not be monitored during the actual life cycling.
h. Periodic measurements: Upon completion of each 5 million operations, the life cycling shall be stopped and the electric power removed from the relays for approximately one hour. Then perform the dc coil resistance, contact resistance, pickup and dropout voltage, and operate and release time tests as specified in 4.5.5, 4.5.8, 4.5.6, and 4.5.9, respectively. The dielectric withstanding voltage and insulation resistance tests, as specified in 4.5.3 and 4.5.4, shall also be performed at the end of the life cycling (50 million operations). The relays shall then be externally examined to verify that no physical damage exists.
4.5.23 Screening (when specified) (see 3.1).
4.5.23.1 Temperature cycling (see 3.28.1). Each relay shall be subjected to 60 temperature cycles. (60 cycles x 4 hours = 240 hours) (see figure 5).
FIGURE 5. Temperature cycling.
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