EL Beam Sensor

EL Beam Sensor


The DGSI EL Beam Sensor is used to monitor differential movement and rotation in structures. Typical applications of the EL Beam Sensor include:

  • Monitoring stabilization measures, such as pressure grouting and underpinning.
  • Monitoring structures which may be affected by nearby tunneling and excavating.
  • Evaluating the performance of bridges and beams under load.
  • Monitoring the stability of structures in landslide areas.
  • Monitoring the deflection and deformation of retaining walls.
  • Monitoring convergence and other movements in tunnels.


The EL Beam Sensor consists of an electrolytic tilt sensor attached to a rigid metal beam. The tilt sensor is a precision bubble-level that is sensed electrically as a resistance bridge. The bridge circuit outputs a voltage proportional to the tilt of the sensor. The beam, which is typically one to two meters long, is mounted on anchor bolts that are set into the structure. Movement of the structure changes the tilt of the beam and the output of the sensor

The voltage reading from the EL Beam Sensor is converted to a tilt reading in mm per meter. Displacements are then calculated by subtracting the initial tilt reading from the current tilt reading and multiplying by the gauge length of the sensor (the distance between anchors). When sensors are linked end to end, displacement values can be accumulated from anchor to anchor to provide a profile of differential movements or settlements.

Because the EL Beam Sensor has a very narrow range, it is necessary to "null" the sensor at installation time. This provides the maximum measurement range and also takes advantage of the sensor's best characteristics.
The EL Nulling Device or the EL Data Recorder are convenient tools for the nulling operation.


The EL beam sensor can detect a change in tilt as small as one second of arc, equivalent to a movement of 0.005 mm per meter of beam.

Since the EL beam sensor has a defined gauge length, changes in tilt can be converted simply and accurately to millimeters of movement, regardless of the rigidity of the structure. Linked end to end, beam sensors can provide absolute displacement and settlement profiles.

A low profile design makes the EL beam sensor practical to install in tunnels and other locations where clearance is important. The length of the beam can be modified to fit the structure, and special mounting brackets provide easy installation on curved or distorted surfaces.

The electrolytic tilt sensor has no moving parts, and its insulated packaging provides thermal symmetry, shielding it from the effects of temperature gradients and radiated heat.

In construction-control applications, beam sensors are connected to a data acquisition system that continuously monitors movements and triggers alarms when threatening movements are detected. In less critical applications, beam sensors can be read manually at a remote terminal box with a hand held readout.

The EL beam sensor provides reliable, high-resolution measurements, is simple to install, and is easily connected to a data acquisition system. It represents an efficient and economical alternative to precision leveling surveys and settlement profiling systems.

For more information

Please download the EL Beam Sensor datasheet and manual. These documents can be viewed and printed with Adobe Acrobat Reader.

EL Beam Sensor & Tiltmeters Specifications

EL Tilt Sensor, Standard 56802100
EL Tilt Sensor, SC 56802120
Sensor Uniaxial electrolytic tilt sensor housed in a weatherproof aluminum enclosure with terminals and cable gland for signal cable. Does not include bracket, beam, or anchors. The standard version of the tilt sensor works with Campbell Scientific CR1000, CR800, and CR10X data loggers. The SC version of the tilt sensor includes a signal conditioning board and a temperature sensor. It works with Campbell Scientific data loggers, the M-Logger, and readouts such as the EL/MEMS data recorder.
Range ±40 arc minutes
Resolution 1 arc second using a Campbell Scientific CR1000 data logger
Repeatability ± 3 arc seconds
Adjustment Range The sensors provides an adjustment range of ±4° to ease installation
Operating Temperature –20 to +50°C.
Dimensions 125 x 80 x 59 mm deep (4.9 x 3.2 x 2.3")
Signal Cable for Standard Sensor 50612804 Shielded cable with four 24-gauge tinned-copper conductors and PVC jacket.
Signal Cable for SC Sensor 50613527 Shielded cable with seven 22-gauge tinned copper conductors and polyurethane jacket.
Order a tilt sensor, a bracket, a beam, and anchors to secure the beam to the structure.
Omni Bracket 56801355K The Omni-bracket holds the tilt sensor onto horizontal, vertical, or inclined beams. Self-tapping screws are included to fasten the bracket to the beam.
1 meter Beam 56801612
2 meter Beam 56801614
3 meter Beam 56801616
3 foot Beam 56801623
6 foot Beam 56801626
10 foot Beam 56801630
Spare End-Bracket 56801815 38 x 38 mm square-section aluminum beam includes two end-brackets. Beams are sized to provide a gauge length that is measured from anchor to anchor. Anchors are not included
Groutable Anchors 56801910K Groutable anchor for beam Includes one allthread stud, low-friction bushings, and other hardware. For stand-alone beam sensors, order two anchors. For linked beams that share an anchor, order one anchor for each beam plus one additional anchor for the last beam.
Order a tilt sensor, a bracket, and an anchor for each sensor.
Rotating L-Bracket 56801350K The L-bracket holds the tilt sensor perpendicular to the structure. The bracket rotates nearly 360 degrees, so it can be mounted on inclined structures, floors, and ceilings, as well.
Omni Bracket 56801355K The Omni-bracket holds the tilt sensor parallel with the structure.
Expansion Anchor 57803128 The expansion anchor is installed in a 9.5 x 64 mm (3/8 x 2.5 in) drill hole and includes a bolt and washer to hold the L-bracket.
Groutable Anchor 57803130K The groutable anchor is installed in a 13 x 90 mm (0.5 x 3.5 in) drill hole and includes a bolt and washer to hold the L-bracket. Requires epoxy grout available locally or ordered below.
Epoxy Grout Kit 57803133 Includes plastic dispenser and cartridge of quickset epoxy grout. Sufficient for 15 anchors.
Campbell Scientific Data Loggers The CR1000 Logger can monitor 12 standard or 3 SC sensors directly. Up to 32 standard sensors or 16 SC sensors can be connected to an AM16/32 multiplexer. See separate datasheet.
M-Logger The M-Logger can monitor one SC sensor directly or 16 SC sensors connected to an AM16/32 multiplexer. See separate datasheet.
EL / MEMS Data Recorder 56813500 This portable readout displays and records readings from SC sensors. Tilt readings are displayed in volts; temperature readings in degrees C. It can also be used for nulling the sensors. See separate datasheet.
EL Nulling Device 56803300 The EL Nulling device provides a convenient way to zero sensors at installation time. The nulling device is compatible with both standard and SC tilt sensors.