ABEM Terrameter SAS 1000 / SAS 4000
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Moreover, it can be used in a wide variety of applications where effective signal/noise
discrimination is needed.
It can be used to determine the ground resistance of grounding arrangements at power plants
and along power lines and (in a pinch) it can even be used as an ohmmeter. The strength of
the SAS 1000 / 4000 is its ability - thanks to the induced polarization mode - to distinguish
between geological formations with identical resistivity, e.g. clay and water.
Some of the highlights in the specifications characterizing the SAS 1000 / 4000 Terrameter
are listed below:
•
Resolution 1
V (at 0.5 sec integration time)
•
Bitstream A/D conversion
•
Three automatically selected measurement ranges (
250 mV,
10 V and
400 V)
•
Dynamic range as high as 140 dB at 1 sec integration time, 160 dB at 8 sec integration
time
•
Precision and accuracy better than 1% over whole temperature range
•
Galvanic separated input channels (SAS 4000)
•
Built-in PC compatible microcomputer
•
More than 1,000,000 data points can be saved on the internal flash disk
•
Fast and highly time-efficient data acquisition
2.4
TYPES OF MEASUREMENT SUPPORTED
The transmitted current is commutated in a waveform suitable either for resistivity surveying
or for induced polarization measurements.
2.4.1
Resistivity measurements
The receiver measures the response voltage signal (plus self-potential and ground noise) at
discrete time intervals when the eddy currents, the induced polarization and the cable
transients have decayed to low levels.
The operator can select between different time scales. Under most conditions a cycle time of
approximately 2.6 sec (which corresponds to an acquisition delay of 0.2 sec and an
acquisition time of 0.3 sec) will work fine. However, under extreme depth and resistivity
conditions the corresponding time cycles should be increased. Under normal conditions the
measuring technique is equivalent to pure DC surveying.
