MIL-DTL-21604F
Z - Rated impedance load
NOTE: Switch wiring shall be size 20 for less than 5 amperes and size 16 for 5 amperes or more. All leads from
switch terminals to power supply or to load resistors shall be at least 2 feet long. Switch jumper wires
shall be as short as practicable.
FIGURE 1. Typical load circuit for electrical endurance test.
4.8.9.2 Mechanical. The switch shall be operated without electrical load for 5,000 cycles of operation. A cycle of
operation is defined as a complete rotation of the switch shaft through all switch positions. Where the switch has
removable stops, the stops shall be removed and a cycle of operation shall be the full 360-degree rotation of the
shaft. Where the switch has nonremovable stops, the rotation of the shaft from the fully counter-clockwise position to
the fully clockwise position and return shall constitute 2 cycles of operation. The cycling rate shall be approximately
15 c/m.
4.8.9.3 Momentary position return. Switches having momentary positions shall be operated to and released from
each momentary position five times before and after the endurance operations.
4.8.9.4 Rotor and shaft alignment (see 3.5.3). For samples selected for the endurance test, the angle between the
center of the detent position and the opening of the contacts shall be measured on break before make contacts of two
terminals. The terminals shall be located on adjacent switch wafers. Three measurements shall be taken for each
terminal and the average angle calculated for each terminal. The method of measurement shall provide for an
accuracy of 15 minutes of angle.
4.8.10 Temperature rise (see 3.14). The temperature rise of the switch stationary contact energized during the
electrical endurance tests shall be determined by means of thermocouples of small wire gauge (28-32 AWG). The
temperature sensitive element shall be placed on the contacts where they first emerge from the switch body.
Temperature measurements shall be taken prior to and immediately following the electrical endurance test. The
contacts shall be energized at rated current at any convenient voltage within the switch rating. Temperature
measurements shall be taken at half-hour intervals until three successive measurements are within 1C.
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