GS_VE-1x_2x_Operation_Manual_V09.docx/14.09.2020
VE-1x/2x Series Velocity Sensor
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2.2.2. Connecting to a Recorder
The following points must be considered when connecting the VE sensor to a recording system:
•
In case of a voltage output the output range is 2.5 VDC to ± 2.5 V (i.e. 0 to 5 V range for peak to peak)
•
In case of a current output the output range is 10 mA to ± 10 mA (i.e. 0 to 20 mA range for peak to
peak).
2.2.3. Cable Configuration, Specification and Length
The cable configuration, specification, length and quality of installation affect the quality of analog signal
received, the cost of materials and the long-term reliability of the system. When cabling is ordered as part of
the system, GeoSIG engineers review the installation plan and the cable specifications as well as
environmental conditions to assist you in achieving a reliable and cost effective installation. Following the
guidelines outlined below will help further ensure your success.
A cable must not only be able to transmit power and signals, but must also survive the environment in which
it is placed. This includes chemical exposure, UV exposure, impact and cut protection, temperature extremes
and any regulatory safety requirements. Because the permutations are so numerous, it is not practical to
specify particular manufacturer's cable part numbers here. However, GeoSIG engineers will work with you to
help you specify an appropriate cable. The electrical parameters required for transmission of signals and power
is discussed below.
The cable construction must be an overall shielded twisted pair type for optimal protection from
electromagnetic interference (EMI) sources along the path of transmission. Normally the shield can be a foil
wrapper with a drain wire. However, if the cable is to be installed in close proximity to high voltage power
cables an overall braided shield is additionally recommended.
For optimum noise shield performance and maximum cable run lengths, the VE velocity sensor signals should
be paired as shown on Table 4.
Table 4. Cable Wire Pair Assignments
Pair
Wire Pair Function
1
X-Signal high and low
2
Y-Signal high and low
3
Z-Signal high and low
4
S_Test and AGND
5
V_EXT and AGND
6
S_MODE and AGND
Connect the cable shield to the local ground at the recorder
Cables do not generate noise. However, longer cables increase the amount of the contributed noise from
external sources. Cables should always be routed as far from power distribution and control wiring as possible.
Again, if the cable needs to be installed close to power cables, an overall braided shield is additionally
recommended.
Cable resistance primarily determines the maximum cable length. This is not an issue related to analog signal
degradation since both the signal currents and the transmission bandwidth are comparatively quite low. The
main limitation is an outcome of voltage drop in the power supply due to cable resistance. The following table
lists typical conductor resistance values for twisted pair shielded cables.
