MIL-DTL-3971 Meters, Time Totalizing, Non-Hermetically Sealed, Electrical: General Specification ForThis specification covers the general requirements for electrically operated nonhermetically sealed meters that automatically measure, and cumulatively register the total operating or idle time of the circuit, machine or system to which connected.

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MIL-DTL-3971F

3.4.12 Dielectric strength. Meters shall be capable of withstanding the application of a

higher than normal operating voltage and frequency for 60 seconds between insulated portions

without damage or flashover, as specified in MIL-DTL-3971/1 and /2.

3.4.13 Weight. The weight of the meter shall not exceed that specified in MIL-DTL-3971/1

and /2.

3.5 Performance. Meters shall meet all performance requirements at the operating voltage, or

over the operating voltage range, as specified.

3.5.1 Starting and stopping. Meters shall be capable of starting and stopping within the time

limitations and at the temperatures specified in MIL-DTL-3971/1 and /2

3.5.2 Operating position. Meters shall be capable of operating in any position within an

accuracy of � 1 percent of total elapsed time at 23�C � 10�C (73.4�F � 18.0�F) when energized

at rated nominal voltage frequency as specified

3.5.3 Vibration.

3.5.3.1 Accuracy. Meters shall remain accurate within � 1 percent of actual elapsed time

during normal vibration and for 24 hours following extended vibration endurance.

3.5.3.1.1 Normal vibration. Meters shall be capable, while energized, of being vibrated as

specified in 4.4.6.6.1. Total test time is 3 hours.

3.5.3.1.2 Extended vibration endurance. Following the vibration specified in 3.5.3.1.1 the

meters shall be capable, while energized, of withstanding extended vibration as specified in

4.4.6.6.2.

3.5.4 Shock.

3.5.4.1 Standard shock. Meters shall operate for at least 1 hour, be accurate within � 1

percent of actual elapsed time and show no evidence of damage (excluding flange) after the

shock test of 4.4.6.7.1.

3.5.4.2 High impact shock. Meters shall operate for at least 1 hour, be accurate within � 1

percent of actual elapsed time and show no evidence of damage after the shock test of 4.4.6.7.2.

3.5.5 Temperature cycling. Meters shall be accurate within � 1 percent of actual elapsed

time and show no evidence of damage during the temperature cycling test of 4.4.6.8.

3.5.6 Moisture resistance. Meters shall operate for at least 1 hour, be accurate within � 1

percent of actual elapsed time and show no evidence of corrosion or damage after being

subjected to the moisture resistance test of 4.4.6.9.