8
Figure 7 - Lightning Protection Scheme
3. TAKING READINGS
The following three sections describe how to take readings using one of readouts available from
CGEO.
3.1. Operation of the CGEO-PR-VW Readout Box
CGEO-PR-VW can be used for Surface Crackmeter measurement. Connect the Readout using the
flying leads or in the case of a terminal station, with a connector. The red and black clips are for the
vibrating wire gage, the white and green clips are for the thermistor and the blue for the shield drain
wire.
1. Turn the display selector to position "B" . Readout is in digits.
2. Turn the unit on and a reading will appear in the front display window. The last digit may
change one or two digits while reading. Record the value displayed. If no reading displays
or the reading is unstable see section 5 for troubleshooting suggestions. The thermistor will
be read and output directly in degrees centigrade.
3. The unit will automatically turn itself off after approximately 15 minutes to conserve power.
Details please see the CGEO-PR-VW Instruction Manual.
3.2. Measuring Temperatures
Each Vibrating Wire Crackmeter is equipped with a thermistor for reading temperature. The
thermistor gives a varying resistance output as the temperature changes. Usually the white and
green leads are connected to the internal thermistor.
