MIL-R-5757J
4.6.19 Overload (applicable to high level relays only) (see 3.21). Relay contacts (both normally open and normally closed) shall be subjected to the tests specified in 4.6.19.1 and 4.6.19.2, as applicable. For double-throw relays, separate tests shall be performed for the normally open and the normally closed contacts. Relay coil energization shall be nonsynchronous with the power supply for ac loads. The number of cycles shall be 100 for dc contact loads, and 200 for ac contact loads ("on" and "off " times shall be approximately equal). The coil shall be energized at rated voltage (or current). Overload current shall be twice rated load current. The opening and closing of all contacts
under test shall be continuously monitored to detect switching of the contacts. The equipment shall be capable of monitoring 40 percent minimum of the actual opened and closed time of each contact. The equipment shall
automatically cut off when a failure occurs, or shall record any failures. The relay case shall be connected to system ground through a normal-blow fuse rated at 5 percent of the test current or 100 mA, whichever is greater. After the test, the fuse shall be tested for electrical continuity.
4.6.19.1 Resistive load. Suitable noninductive resistors shall be used. Cycling rate shall be 20 cycles per minute
(cpm) ±2 cpm.
4.6.19.2 Inductive load. Cycling rate shall be 10 cpm ±1 cpm. Inductive load testing shall be approved by the qualifying activity (see 6.10).
4.6.19.2.1 Inductive load, dc. Unless otherwise specified (see 3.1), dc inductive loads shall be computed in accordance with the following procedure:
a. The relay shall be mounted in its normal operating position on a nonmagnetic plate with no immediately adjacent metal.
b. The load circuit shall be energized through a bounce free contact from a power supply regulated to within 5 percent of the specified rated voltage (or current) as shown on figure 10.
c. By measuring the time for the current to reach 63 percent of its final value, the dc inductance is calculated as: L = Rt
Where:
L - is the inductance in henries,
R - is the resistance of the load circuit, and
t - is the time in seconds for current to reach 63 percent of its final value.
4.6.19.2.2 Inductive load, ac. The load shall consist of inductive and resistive elements with 0.7 lagging power
±0.05 lagging power factor at the voltage and frequency specified (see 3.1).
4.6.20 Life (see 3.22). Unless otherwise specified (see 3.1), relays shall be operated for 100,000 cycles with contacts loaded in accordance with 4.2.3 and 4.6.20.1 through 4.6.20.4 inclusive, as applicable. Relay coil energization shall be nonsynchronous with the power supply for ac loads. Each relay case shall be connected to system ground through an individual normal-blow fuse rated at the greater of 100 mA or 5 percent of load current. The ambient temperature of the interior of the test chamber shall be +125°C minimum. The contact resistance or voltage drop, as applicable, shall be monitored during 40 percent minimum of each "on" and each "off " period. The monitoring equipment shall automatically hold the relay under test in the state in which the failure occurs (energized or de-energized) and the contact voltage shall be removed. All contacts in each sample unit shall switch identical loads. Following cycling, the electrical continuity of each case-grounding fuse shall be checked.
a. Level I. Relays shall be subjected to 100,000 operations (unless otherwise specified; see 3.1) at the rate of
20 cycles ±2 cycles per minute, with "on" and "off " times approximately equal.
b. Level II. Relays shall be subjected to 50,000 operations (unless otherwise specified; see 3.1) at the rate of 29 seconds ±3 seconds "on" and one and one-half seconds ±0.5 second "off ".
4.6.20.1 Resistive load. Cycling rate shall be 20 cycles ±2 cycles per minute. Suitable resistors shall be used. Current shall be rated resistive current as specified (see 3.1).
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