The strain gauge operates on the
principle that a tensioned wire, when
plucked, vibrates at its resonant frequency.
The square of this frequency
is proportional to the strain in the
wire.
The gauge is constructed so that a
wire is held in tension between two
mounting blocks that are welded to
the structural member. Loading of the
structural member changes the distance
between the two mounting
blocks and results in a change in the
tension of the wire.
An electromagnet is used to pluck
the wire and measure the frequency
of vibration. A change in strain is the
difference between the current reading
and the initial reading multiplied
by a gauge factor.
An electromagnet is used to pluck
the wire and measure the frequency
of vibration. Strain is then calculated
by applying calibration factors to the
frequency measurement. |
The arc-weldable strain gauge is
supplied with two mounting blocks.
The mounting blocks are attached to
a spacer bar and welded to the structural
member.
After the welds cool, the spacer bar is
removed and the strain gauge is
inserted in its place. The gauge is
then connected to a readout and
adjusted to measure tension, compression,
or both.
The strain gauge can also be used
with groutable mounting blocks,
which are anchored in holes drilled
into the concrete structure. |
Permanently Attached Coils: The
coils used to excite and read the
vibrating wire are permanently
attached to the gauge. This prevents
accidental separation from the strain
gauge body during installation.
Install on Steel or Concrete: Use
the weldable mounting blocks for
steel and the groutable mounting
blocks for concrete.
Field Adjustable: The strain gauge
can be adjusted so that most of its
range is available to measure compression
or tension, as required by
the application.
Reliable Signal Transmission: The
arc-weldable strain gauge provides a
strong signal which can be transmitted
reliably over long distances with
properly shielded cable. |
| VW Arc-Weldable Gauge |
SI52640306 |
| Vibrating wire strain gauge for monitoring strain
in steel structural members. Part number
includes strain gauge with thermistor, and two
weldable mounting blocks. Signal cable is
ordered separately. |
| Range |
3,000 microstrain. User can set tension
to maximize range for the application. |
| Resolution |
1 microstrain with VW Indicator |
| Accuracy |
± 0.1% FS |
| Thermal Coefficient |
11ppm / °C |
| Length |
150 mm (5.875"). Long base gauges
are available on special order |
| Mounting-Block |
38 x 10 x 19 mm
(1.5 x 0.375 x 0.75") |
| Installation Kit |
SI52630330 |
| Kit includes two spacer rods, an allen wrench,
and two spare set-screws. |
| Spare Mounting-Blocks |
SI52630350 |
| Two mounting-blocks with set-screws. Used if
gauge is repositioned. |
| Groutable Mounting Blocks |
SI52640410 |
| Two mounting blocks with 3" long groutable
anchors attached. Used to mount strain gauge to
concrete. |
| Signal Cable |
SI50613324 |
| Shielded cable with four 24-gauge tinned-copper
conductors and flexible polyurethane jacket
rated to 80°C(176°F). |
| Terminal Box for 6 sensors |
SI57711606 |
| Terminal Box for 12 Sensors |
SI57711600 |
| Terminal Box for 24 Sensors |
SI97711624 |
| Provides terminals for signal cable from 6, 12, or
24 sensors. Sensors are selected by rotary switch.
Dimensions of 6-sensor box are 240 x 190 x 120
mm (9.5 x 7.5 x 4.75"). Dimensions of 12 and
24-sensor boxes are 290 x 345 x 135 mm (11.5 x
13.5 x 5.25"). |
| Universal Connector |
SI57705001 |
| For terminating a single cable. Connector not
required when sensors are connected to a terminal
box, a data logger, or to the terminal posts
on the VW Data Recorder. |
| VW Data Recorder |
SI52613500 |
| Jumper Cable for Terminal Box |
SI52613557 |
| The VW Data Recorder displays VW sensor readings
in Hz or H2/1000 and thermistor data in
degrees C. It can also record the readings.
The jumper cable is required when the VW Data
Recorder is to be connected to a terminal box or
to a connector attached to signal cable. |
| VW MiniLogger |
SI52613310 |
| The VW MiniLogger is a compact, low-cost data
logger for one sensor |
e.jpg)