MANUAL
Equipment Inspection
Upon arrival, and before each use, inspect for the following items:
• VwAnalyzer • USB
cable
• Carrying
case • Phillips
screwdriver
•
Manual (this document)
•
5-AA batteries
•
Measurement cable
•
Hand strap
Precautions
•
WARNING: Disconnect power from active automated systems prior to connecting and
measuring a sensor with a VWA on the automated system
•
CAUTION: Avoid direct contact with water (IP-62)
•
CAUTION: Store and transport in the protective case
•
CAUTION: Measurements are not pressure or temperature compensated
•
CAUTION: Do not force measurement cable connection ; cable fits one way
•
CAUTION: Hold the device properly, do not hang/carry from measurement cable
Warranty & Service
•
Warranted for one (1) year,
www.campbellsci.com/terms
•
For repair, see
www.campbellsci.com/repair
•
For assistance, call (435) 227-9100
Overview
The VWA uses patented VSPECT
TM
technology for the most reliable vw measurement available. The
VWA converts measurements to engineering units, generates a printable PDF report, and saves a
CSV summary file. The graphical display allows you to confirm sensor output and operation. VSPECT
technology eliminates disruptive noise interference and provides sensor diagnostics for the best
measurement possible. VSPECT noise immunity allows gages that are otherwise unreadable to be
evaluated with confidence.
A project file maintains Site/Sensor information for 40 unique sites with 22 sensors per site. Site/
Sensor locations are geolocated, allowing the internal GPS to walk a user directly to the sensor. Site/
Sensor and user information can be created or edited on the device or with a computer using the free
VwProjects software.
Specifications
Vibrating wire measurement
Resolution:
0.001 Hz RMS
Speed:
1 second (fastest)
Excitation:
2V, 5V, 12V (user selectable)
Accuracy:
±0.005% of reading
Method:
VSPECT (Vibrating Wire Spectral Analysis), U.S. Patent No. 7,779,690
Temperature (resistance) measurement
Resolution:
0.01 Ω RMS
Accuracy:
±0.15% of reading
General information
1
Memory:
1,700 site/sensor measurements (most recent
2
)
40 unique sites, 22 sensors per site
240 single measurements (most recent
2
)
16,500 continuous measurements (most recent
2
)
80 MB USB memory (PDF, CSV, VWA, and other files
3
)
GPS:
± 5m (16.4 ft) typical; ±1 ms time sync (WGS 84 Datum)
Battery type/life:
5-AA (1.5 V)/20 hours continuous use
Weight:
0.34 kg (0.75 lb)
Dimensions:
200 x 100 x 58 mm (7.9 x 3.9 x 2.3 in)
Compliance:
CE, RoHS
Operating Temp:
(-20 to 70 °C)
Enclosure:
IP62
EU Declaration of Conformity:
www.campbellsci.com/vwanalyzer
1
Non-volatile memory stores data, reports, and project files
2
When memory is full, new data will overwrite the oldest data
3
Memory managed by users, files will need to be deleted/transferred when full
Operating System
A new operating system (OS) may be installed to update features or the sensor library. Back up all
data and the project file prior to working with the OS. A factory reset is done from
System Settings
.
OS update procedure:
1.
Back up project files/data
2.
Download the .obj file; see
Downloads
3.
Save file to the VWA root directory
4.
Cycle power
5.
Verify OS version in
System Settings
Temperature Measurement
Most vw sensors have a resistance (thermistor/RTD) measurement to calculate sensor temperature.
When a sensor is selected with the sensor library, the equation and conversion coefficients are
automatically selected for the manufacturer specific vw sensor. Users can view or create custom
temperature calculations in
Measurement Settings
. When using
Read
,
Options
can be selected
to quickly choose a temperature conversion.
Measurement Screens
When a sensor is measured, four screens display the results, the right soft key is used to
advance to the next screen.
1st Screen – Measurement
Summary screen setup by the user
•
User selectable summary boxes (frequency, digits,
B-units, temp, ohms)
•
Spectrum graph (optional)
•
Change settings in
Measurement Settings
2nd Screen – Details
Metadata including diagnostics
Tip
:
On-screen side arrows allow historic data
comparison
3rd Screen – Frequency Spectrum
Frequency spectrum graph
•
Sensor signal is defined as the largest signal within
the frequency sweep range
•
Visually compare the sensor signal to noise signals
4th Screen – Time Series
Time series graph
•
Visually see the raw input signal
Sensor Library
The sensor library contains preprogrammed sensors from common vw sensor manufacturers. The library can be
accessed on the VWA or with
VwProjects
when a new sensor is created or edited using
Site/Sensor
. Use of
the sensor library enables:
•
Manufacturer-recommended sweep frequencies
•
Field conversion from frequency to engineering units
•
Sensor specific calibration inputs
Notes
:
•
Engineering units reported are NOT corrected for temperature or barometric pressure
•
Temperature is calculated with manufacturer specific conversions, see
Temperature Measurement
•
A
Continuous
measurement can graph the sensor response in engineering units when linked to a sensor with
calibration values applied
•
Calibration inputs are unit specific to match manufacturer calibration sheets. When the selected output units
are different than manufacturer calibration units, an automatic unit conversion will be applied
Measurement Reports
Printable PDF measurement reports are saved when using
Read & Record
. There are two
types of measurement reports:
Single Measurement Report
Created when a measurement is performed from
Site/Sensor
or
Single
read. Use as field
documentation, baseline reading, or as installation record.
Continuous Measurement Report
Optionally created with
Continuous
read. Use for monitoring changing field conditions, or
during installation (push-in piezometer, well pump test, sensor response, etc.).
Using VwProjects
Project Files
A project file contains site, sensor, and user information. Project files can be shared between VWAs.
A project file can be used to:
•
Back up Site, Sensor, and User information
•
Transfer project file data to another VWA device
•
Create or edit a project file on a PC with VwProjects
•
Import/export project file in
System Settings
(see steps below)
•
Maintain up to 20 users per VWA
•
Maintain up to 880 unique sensors (40 sites, 22 sensors/site per VWA)
Note
:
A project file contains information about Sites, Sensors, and Users. Measurement data is
saved in the PDF and CSV files, and is NOT saved or transferred in a project file.
VwProjects
VwProjects uses a keyboard and PC to easily create and edit project files. The software can create a
new project file or open an existing project file created from a VWA or a PC. The screenshot
below illustrates the various buttons and capabilities of the software:
30
Create a new project file
35
Create and edit Sensors
31
Open an existing project file
36
Site/Sensor Information
32
Save the current project file
37
Sensor Details
33
Create and edit Users
34
Create and edit Sites
Note: When saving a project file on the VWA or PC , there are 2 save file options:
•
Append File
: New or changed information will be added or updated on the
VWA.
•
Overwrite/ Backup file
: When loaded to a VWA, all the old information will be
erased and overwritten with the new project file information.
Loading project file to a VWA
1.
Connect to a PC with USB cable (see
Data Retrieval
)
2.
Copy the project file from PC to the USB memory of the VWA
3.
Eject the USB connection from the PC, disconnect USB cable
4.
Select
Import
in the project file option in
System Settings
5.
Select your project file, select
Import
Exporting project file from a VWA
1.
Select
Export
in the project file option in
System Settings
2.
Select the file type
3.
Retrieve the project file with PC
4.
Save or edit the project file as needed
GPS and Time Zone
The integrated, non-survey grade GPS is used to update the internal clock and provide approximate
location data for reports.
Select
System Settings
to adjust the GPS time to your location or turn off the GPS. The time can be
manually set when the GPS is turned off. Daylight Saving Time can be applied as needed.
!
11
VSPECT Measurement
VSPECT
TM
provides the best vibrating wire measurement available. Sensor frequency is easily identified while filtering out environmental and electrical noise that affects the quality of other vibrating wire readers.
VSPECT
TM
provides measurement diagnostics to understand sensor response, installation quality, and identify incorrect wiring or damaged sensors.
Output and Diagnostics
Sensor Frequency
1
(
Hz
)
Frequency is the basic measurement from a vibrating wire sensor. The frequency can be
converted into engineering units (pressure, displacement, etc.) and is identified as the largest
measured amplitude signal within the frequency sweep.
Sensor Amplitude
2
(
mV RMS
)
Signal strength from the vibrating wire sensor. Amplitude varies and is affected by the sensor
type, excitation strength (adjustable), and sensor cable length.
Signal-to-Noise Ratio
2
(
unitless
)
The signal-to-noise ratio is calculated as sensor signal amplitude divided by the largest noise
amplitude within the sweep frequency. A low signal-to-noise ratio indicates a weak sensor
signal or a noisy environment.
Noise Frequency
2
(
Hz
)
The largest amplitude noise signal within the frequency sweep.
Decay Ratio
2
(
Hz
)
Signal attenuation; how quickly the signal strength decreases.
Thermistor/RTD Resistance
1
(
ohms
)
Used to calculate sensor temperature and correct for thermal effects
3
.
1
Frequency and resistance are measured values
2
Diagnostic values used to describe the quality of the frequency measurement
3
The VWA measures the vw sensor temperature (when present); post processing is required for thermal and
barometric corrections. An automated data acquisition system (ex. CR6) with an integrated barometer can
apply temperature and pressure corrections.
Warning Thresholds
Measurement warning thresholds can be set in
Measurement Settings
. Thresholds provide a
warning for questionable measurements (incorrect wiring or damaged sensors). When a threshold is
triggered, the alarm can be selected to display a brief list of field troubleshooting tips.
Amplitude
The default is 0.10 (mV RMS), intended to identify weak signals
for additional review.
Signal-to-Noise Ratio
The default is 5.0 (unitless), intended to identify extreme noise
environments for additional review.
Data records normally when a threshold is triggered. It is the responsibility of the user to exercise
engineering judgment with thresholds, graphs, and additional diagnostics to determine if the
measurement is acceptable.
Note
:
A frequency sweep excites frequencies within the expected frequency response
range of the sensor. See the sensor manual for an expected frequency operating range.
Measurement Graphs
The following two sets of graphs illustrate the use of VSPECT
TM
to identify a sensor signal in a quiet
and noisy environment. Both graphs were created from VWA reports using the same sensor. Fig. 1
was measured in an electrically quiet environment, while Fig. 2 was measured in an electrically noisy
environment (AC power) similar to what can be seen in a field environment (power lines, motors,
radio signals, etc.). The time series on Fig. 1 shows a relatively clean signal that is more clearly
identified on the frequency spectrum . The time series on Fig. 2 shows the influence of
the noise . Vibrating wire readers that only use the time series to determine the frequency
may report an incorrect frequency as a result of noise. The frequency spectrum (VSPECT
TM
) filters the
noise and easily identifies the sensor signal . VSPECT
TM
provides noise immunity by correctly
identifying the sensor signal and ignoring the influence of electrical noise that plagues
time-domain-based vibrating wire readers.
21
The Frequency Spectrum graph shows signals with respect to frequency (VSPECT
TM
)
22
The sensor signal is determined as the largest signal within the frequency sweep
23
The Time Series graph shows raw signals observed with respect to time
24
A time series with minimal noise influence
25
The frequency sweep is shown as the white area on the graph, only signals within the
frequency sweep will be considered as a possible sensor signal
26
Noise is identified and ignored
27
A sensor signal is easily identified even when noise is present in the measurement
28
A time series with observable noise
29
Noise in the time series (this is what confuses non-VSPECT
TM
devices)
25
21
22
23
24
25
26
27
28
29
24
22
21
28
29
28
26
27
30
33
34
32
31
35
36
37
30
31
32
WARNING:
A factory reset deletes
all data.
2
Figure 1:
VW Signal
Figure 2:
VW Signal With Noise
