7
2.7 Lightning Protection
The Model 4430 Vibrating Wire Deformation Meter, unlike numerous other types of
instrumentation available from Geokon, does not have any integral lightning protection
components, i.e., transzorbs or plasma surge arrestors. Usually this is not a problem however, if
the instrument cable is exposed, it may be appropriate to install lightning protection components,
as the transient could travel down the cable to the deformation meter and possibly destroy it.
Note the following suggestions:
•
If the gauge is connected to a terminal box or multiplexer components such as plasma surge
arrestors (spark gaps) may be installed in the terminal box/multiplexer to provide a measure
of transient protection. Terminal boxes and multiplexers available from Geokon provide
locations for installation of these components.
•
Lighting arrestor boards and enclosures are available from Geokon that install near the
instrument. The enclosure has a removable top. If the protection board (LAB-3) is damaged,
the user may service the components (or replace the board). A connection is made between
this enclosure and earth ground to facilitate the passing of transients away from the gauge.
See Figure 7. Consult the factory for additional information on these or alternate lightning
protection schemes.
•
Plasma surge arrestors can be epoxy potted into the gauge cable close to the sensor. A ground
strap would connect the surge arrestor to earth ground; either a grounding stake or other
suitable earth ground.
Terminal Box/Multiplexer
Instrument Cable
LAB-3 Enclosure LAB-3 Board
Deformation Meter
Ground Connections
Surface
(usually buried)
Figure 7 - Lightning Protection Scheme