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 MIL-HDBK-419A
Table 1-9. Transient Occurrences, High-Incident Lightning Areas
No. of Transients
Transient
Amplitude (Amperes)
in 10-year Period
2,500
368
500
to
2,501
to
5,000
402
5,001
to
10,000
420
10,001
to
20,000
333
20,001
to
30,000
140
30,001
52
to
40,000
40,001
to
50,000
17
50,001
to
75,000
16
75,001
to
2
100,000
Table 1-10. Transient Occurrences, Low-Incident Lightning Areas
No. of Transients
Transient
Amplitude (Amperes)
in 10-year Period
500
to
2,500
37
2,501
to
5,000
40
5,001
to
10,000
42
10,001
to
20,000
33
20,001
to
30,000
14
30,001
to
40,000
5
40,001
to
50,000
1.75
50,001
to
75,000
1.5
75,001
to
100,000
0.175
(3) Transient amplitudes are less at small electronic facilities. Recorded data substantiates that
large electronic facilities tend to attract higher intensity strikes than small electronic facilities. The transient
amplitudes listed in Sections 1.3.3.5.13a(l) and a(2) are for large electronic facilities, and the amplitudes should
be decreased by 50% for small electronic facilities. Large electronic facilities are defined as requiring more
than 100 amperes per phase for normal operation. The transient amplitudes of Tables 1-9 and 1-10 should be
decreased by 50% when relating to a small facility.
1-63
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