d.
Sand and dust: Wind driven for up to [9.6] [_____] km per hour
[6] [_____] miles per hour;
e.
Rain: 50 mm 2 inches per hour and 125 mm 5 inchesper hour cyclic
with wind plus one period of 300 mm 12 inches per hour;
f.
Humidity:
5 to 95 percent;
g.
Fungus: Warm, humid atmosphere conducive to the growth of
heterotropic plants;
h.
Salt fog:
Salt atmosphere with 5 percent salinity;
i.
Snow: Snow loading of 234 kg per square meter 48 pounds per
square foot (psf) per hour; blowing snow of 22.5 kg per square
meter 4.6 psf per hour;
j.
Up to 12.7 mm 1/2 inch of radial ice;
k.
Wind: Up to 80 km/h 50 mph with gusts to 106 km/h 66 mph, except
that fence sensors shall detect intrusions up to 56 km/h 35 mph;
and
l.
Acoustical noise: Components shall be suitable for use in high
noise areas above 110 dB, such as flight lines, runup pads, and
generator sites without adversely affecting their performance.
2.4.5.3
Lightning and Power Surges
Intrusion detection, video circuitry, and communication circuits that lead
to the central alarm reporting and display unit shall be protected at both
ends against excessive voltages. This requirement shall apply for circuits
that are routed both in underground conduits and overhead runs. As a
minimum, install primary detection devices, such as three electrode
gas-type surge arresters, and secondary protectors to reduce dangerous
voltages to levels that will cause no damage. Fuses shall not be permitted
as protection devices. Provide fail-safe gas tube type surge arresters on
exposed IDS data circuits. Breakdown voltage for the unit shall be 300 to
500 volts dc. Unit shall have equal performance for bipolar operation with
automatic reset feature and a minimum life of 1000 surges with 10 times
1000 microsecond waveform at 1000 amperes. Provide low capacitance
transient suppression type video lightning surge arresters on exposed video
cables. Breakdown voltage for the unit shall be 7 to 9 volts at 10
milliamperes. Maximum clamping voltage shall be 15 volts at 130 amperes
for one time 50-microsecond waveform. Minimum life shall be 1000 surges
with one time, 50-microsecond waveform at 130 amperes. There shall be no
degradation in video quality. Units shall be UL listed. Transient
protection shall protect against spikes up to 1000 volts peak voltage with
a one-microsecond rise time and 100-microsecond decay time, without causing
false alarms. The protective device shall be automatic and self-restoring,
and shall be on duty at all times. Circuits shall be designed or selected
assuming a maximum of 25 ohms to ground.
2.4.6
IDS components employing electromagnetic radiation shall be designed and
constructed to provide maximum practical invulnerability to electronic
SECTION 13703N
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