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MIL-PRF-39005 Resistors, Fixed, Wirewound \(Accurate\), Nonestablished Reliability, Established Reliability, General Specification ForThis specification covers the general requirements for nonestablished reliability \(non-ER\), established reliability \(ER\), accurate, wire-wound, fixed resistors that have a maximum resistance tolerance of 1 percent and a high degree of stability with respect to time under specified environmental conditions. The resistors are capable for continuous full-load \(or voltage\) operation at any ambient temperature up to 125??C, and when derated, up to 145??C \(see 6.5\). They are not capable for application where the alternating current \(ac\) characteristics are of critical importance. ER resistors have life failure rates \(FR\) ranging from 1.0 percent to 0.001 percent per 1,000 hours \(see 1.2.1.5\). These FR are established at 60-percent confidence level on the basis of the life tests. The FR, identified by the appropriate symbol, is referred to operation at full rated voltage and temperature.

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MIL-PRF-39005G

TABLE XV. DC resistance test voltages.

Resistance,

0.5 watt

Less than

nominal

and greater

0.5 watt

ohms

Maximum test voltages

less than 1 ohm

0.1

0.05

1 to

9.999 inclusive

0.3

0.15

10 to

99.99 inclusive

1.0

1.00

100 to

999.9 inclusive

3.0

3.00

1,000 to 9,999

inclusive

10.0

3.00

10,000 to 99,999

inclusive

30.0

10.00

100,000 and higher

inclusive

100.0

30.00

4.8.6 Solderability (applicable to terminal "L" only)(see 3.10). Resistors shall be tested in accordance

with method 208 of MIL-STD-202. The following detail shall apply: Either one or two of the leads shall be

tested, as applicable (see table IX).

4.8.7 Dielectric withstanding voltage (see 3.11). This test shall be performed not less than 10 minutes,

nor more than 30 minutes, after the preceding test.

4.8.7.1 Atmospheric pressure. Resistors shall be tested in accordance with method 301 of

MIL-STD-202. The following details and exceptions shall apply:

a. Special preparations: Resistors shall be placed in a conductive material which will conform to the

resistor surface so that between 90 percent and 100 percent of the outer periphery is contacted.

The conductive material shall be centered on the resistor body. Care should be taken that any

part of the resistor lead is as far away from the conductive material as possible.

b. Initial measurement: DC resistance shall be measured as specified in 4.8.5.

c. Magnitude of test voltage: 750 V rms.

d. Nature of potential: An ac supply at commercial line frequency and waveform.

e. Duration of application of test voltage: 1 minute.

f. Rate of application of test voltage: The test voltage shall be raised from zero to 750 V rms, as

uniformly as practicable, at a rate of approximately 100 volts per second.

g. Points of application of test voltage: Between resistor terminals connected together and mounting

hardware, or the conductive material, as practicable.

h. Measurement after test: DC resistance shall be measured as specified in 4.8.5.

i. Examination after test: Resistors shall be examined for evidence of flashover, mechanical

damage, arcing, and insulation breakdown.