Section 5 Geophone Testing Io
SENSOR
68
SMT-200 Operations and Technical Manual 2.00/R1
Frequency, Damping and Sensitivity Failures
If all of these parameters fail together then check for external noise
(electrical or mechanical). Ensure the noise test is selected and check the
noise level. These tests are grouped together as they are derived from the
same test. Noise is also likely to result in increased distortion.
Failure of frequency, damping or sensitivity on a particular string is likely to
be due to an element failure. The test procedure is similar to that just
described except a test is run and processed each time.
Resistance Failures
Resistance is directly related to temperature. If there is a continuous failure
on resistance but sensitivity is ok then it is possible the temperature of the
string is incorrectly set. Check the Smartec sensor is enabled and the
SMT-200 Bendix connector (containing the sensor) is at a similar
temperature to the string under test.
Check also the geophone interval and lead-in is correctly set.
Distortion Failures
Check the noise level is not excessive. Troubleshooting procedure is the
same as for continuous impedance. Check all geophones are securely
planted and are planted upright. A common cause for distortion failures is
the coil impacting the case end plate if there is an excessive tilt on the
phones. The manufacturers specification sheet will state the maximum angle
of tilt that is allowable.
If the elements natural frequency is less than 12 Hz then it is advisable to
run the test at constant excursion. For these phones the test may fail if the
distortion tests are run at the natural frequency without compensation.
--Test results--
No. 1
Temp 20.0 °C
Pol 1
Leak 1401 Mohm
Res 382 ohm
Freq *10.59 Hz
Damp *0.270
Sens *27.1 V/m/s
Dist 0.04 %
Imp 2205 ohm
Frequency High
0 Back to Main
- Repeat Test
Start next Test
--Test results--
No. 1
Temp 20.0 °C
Pol 1
Leak 1401 Mohm
Res *398 ohm
Freq 9.91 Hz
Damp 0.259
Sens 28.7 V/m/s
Dist 0.04 %
Imp 2205 ohm
Resistance High
0 Back to Main
- Repeat Test
Start next Test
--Test results--
No. 1
Temp 20.0 °C
Pol 1
Leak 1401 Mohm
Res 382 ohm
Freq 9.91 Hz
Damp 0.259
Sens 28.7 V/m/s
Dist *0.22 %
Imp 2205 ohm
Distortion High
0 Back to Main
- Repeat Test
Start next Test
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