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Product
Description
High voltage transients caused by lightning or other electrical
disturbances have the ability to easily destroy semiconductor
junctions, and thus, cause equipment failure. A lightning strike
in the vicinity of data lines can cause induced ground currents
which can also do serious damage. Typical leading edge
wave-fronts of a lightning strike rise at the rate of 1,000
Volts per microsecond. The Model 22NX Lightning Sponge is
designed to accommodate these transients, slow them down and
redirect them to a low impedance path to earth ground.
RS-422/RS-485 is a low voltage, high speed interface. Protection
of these RS-422/RS-485 lines is accomplished by using the 4-wire
Model 22NX. It limits the voltage to approximately 7.5 Volts and
passes signals whose data transfer rate can exceed ten million
bits per second. The protection circuits incorporate 3 separate
stages of limiting high voltage transients, gas tubes and two
stages of avalanche diodes. The DC series resistance is limited
to approximately 5 Ohms and the response time is measured in
nanoseconds. It is good practice to install a Model 22NX on each
end of the 4-wire transmission line. The output voltage is
limited to ±7.5 volts for the Model 22NX.The Model 22NX provides
4-wire screw terminals on both ends for terminating the 4-wire
lines. An additional screw terminal is provided to make the
connection to earth ground. This wire should be at least #12
gauge or larger and be as short as possible. It will conduct the
surge to earth ground (power ground or water pipe).
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