MIL-DTL-83729C
TABLE II-I. Group A inspection sampling plan.
Sample size for tests in
Sample size for tests in
accordance with 3.6,
Lot size
mechanical inspection
2
to 12
All
All
13
to 19
All
13
20
to 150
20
13
151
to 280
20
20
281
to 500
47
29
501 to 1,200
47
34
1,201 to 3,200
53
42
3,201 and above
68
50
4.6 Methods of inspection.
4.6.1 Visual and mechanical inspection. Choppers shall be inspected to verify that the materials, design,
construction, physical dimensions, marking, weight, and workmanship are in accordance with the applicable
4.6.2 Seal (see 3.6).
4.6.2.1 Seal test I (see 3.6.1). Choppers shall be tested as specified in method 112 of MIL-STD-202, test
condition letter B, except use water at room ambient temperature in lieu of silicone oil at a pressure of 1.5 inches of
mercury. Care should be exercised to differentiate between actual leakage and bubbles caused by air dissolved in
the liquid. Choppers that are sealed except for vent lube shall be immersed in water with 15 pounds per square inch
of dry nitrogen applied to vent tube. Caution is to be exercised so that water does not enter vent lube.
4.6.2.2 Seal test II (see 3.6.2). Choppers shall be tested in accordance with method 112 of MIL-STD-202, test
condition letter C, procedure III or IV. Leakage-rate sensitivity shall be 1 x 10-8 atm cc/s.
4.6.3 Electrical characteristics.
4.6.3.1 Contact resistance (see 3.7.1).
4.6.3.1.1 Static contact resistance (or voltage drop (method I). Choppers shall be tested in accordance with
method 307 of MIL-STD-202. The following details and exception shall apply:
(a)
Method of connection: Between the measuring apparatus and the chopper terminals (for choppers with
wire-lead terminals), this measurement shall be made 3/8 ± 1/8 inch from the emergence of the lead from
the chopper. Voltage-sensing leads shall be connected in such a way as to exclude the resistance of the
current-carrying leads.
(b)
Test current: Rated contact current.
(c)
Maximum open-circuit test voltage: The lower of rated contact voltage or 6.0 Vdc.
(d)
Points of measurements: All mated contacts in their closed position: the coil shall be energized with dc
voltage which is 75 percent of rated ac coil voltage. The coil polarity shall be applied in both directions in
order to transfer contacts.
(e)
Number of actuations prior to measurement: None.
(f)
Number of test actuations: One for each contact pair (no contact voltage shall be applied during contact
transfer).
(g)
Number of measurements per actuation: One in each closed contact position. In the event the
measurement exceeds 0.10 ohm, the contact resistance shall be measured at the chopper terminations to
determine if the excess is due to socket resistance. If so, the chopper shall be considered to have met the
requirement.
4.6.3.1.2 Dynamic (method II). Contact resistance measurement shall be made with the chopper in the circuit on
figure 1.
(a)
Connect the chopper as shown on figure 1. Energize the coil with nominal rated voltage and frequency.
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