Description

Electrical crackmeters, for some applications, may be an alternative to vibrating wire crackmeters. Potentiometric and electromagnetic (LVDT) Electrical crackmeters are currently available .
The choice between the various types of transducer depends on specific application and can be suggested by our technicians according to information provided by clients or acquired on site.
They are generally used to control: surface cracks in buildings, civil works and historical works, openings in the ground and for monitoring of structural joints in dams, bridges or artifacts.
Vibrating wire crackmeters can be read manually with our portable units (DEC 3000 and handheld units) or automatically with our datalogger (CUM3000).
They can be integrated into automatic monitoring systems and manage phenomena and alarms locally and remotely in real time.
For specific needs and requests and needs, we are able to design and manufacture customized products different to standard.

Applications

These crackmeters find application in many situations, in particular in all cases where continuous data collection is needed such as monitoring:

  • load tests on slabs
  • structural deformation due to very rapid load changes
  • cracks under dynamic conditions, etc.
  • bridges
  • tunnels
  • landslides; earth or rock
  • residential buildings
  • rods
  • monuments
  • various

Features and Benefits

  • High resolution and sensitivity
  • High measurement speed
  • Extremely robust
  • Good resolution and linearity
  • Simple and economical
  • Simple measuring method

Measuring Principle

The potentiometric strain gauge/crackmeter is a simple linear or circular voltage divider, depending on the specific application. A resistive track is run by a slider which identifies the measuring points where the partition occurs. The cursor position locates the position of the measuring point. Properly powered the instrument releases an analog output signal proportional to the displacement.
The LVDT extensometer is made from a tube composed of three windings arranged with parallel axes, with inside a movable cylindrical ferromagnetic core, usually characterized by high magnetic permeability. The central winding is called primary and the other two secondary: the primary is connected to an AC voltage generator, while the heads of the secondary windings measure the output voltage which is proportional to the displacement.

MODEL LVDT Model Linear Potentiometric
Sensor of temperature No No
Measuring Range Da 0 ÷ 2 mm a 0 ÷ 600mm ± 5 ÷ 150 mm
Linearity % ± 0,3% F.S. ÷ 0,5% F.S. From 0,5 a 0,05 FS, according to FS
Output ±5V; 4-20 mA Potentiometer; 4-20ma (upon request)
Supply Voltage ± 9-36 Vdc From 15 to 60 V, a seconda del F.S.
Anchoring type Dowels, threaded bars, fixtures Dowels, threaded bars, fixtures
Operation Temperature -40 ÷ 85 °C -20 ÷ 80 °C

Accessories and related products

Triaxial Deformometer Allows the mounting of the 3 crackmeters for the monitoring of a crack into the three directions x,y,z,
Fixing Kit Axis Y Allows the monitoring of the crackmeter for the control of the axis Y
Fixing Kit Axis Z Allows the monitoring of the crackmeter for the control of the axis Z
Junction Boxes Different Models for the connection to the different instruments
Multipolar cable Different conductors for the connection of different sensors to one cable
DEC 5 Portable Readout Unit
DEC 3000 Portable Datalogger
CUM 3000 Multichannel Datalogger
MUX Multiplexer for the connection of different sensors to the Datalogger

Technical Assistance

If you have any requests or questions about our instruments or if you have special needs that require different solutions from the standard, please contact us. Our team will provide all the necessary information and will be very happy to work with you to study, develop and customize instruments and solutions suitable for your specific needs.
All information in our datasheet is subject to change without prior notice.
Please check the datasheet/details carefully and contact Pizzi Instruments for further information.