EDS-20V/21V Vibrating Wire Extensometer
- Manufacturer: Encardio Rite
- Category: Structural monitoring, SENSORS
EDS-20V/21V Vibrating Wire Extensometer
The Encardio Rite EDS-20V/21V vibrating wire extensometer measures strain in concrete and steel. Applications include structural monitoring, infrastructure inspection, and geotechnical instrumentation. The output is in frequency (VW), and the result is expressed in microstrain (µε).
Operating principle
A high-strength steel magnetic wire is pre-tensioned between two anchor points. An electromagnetic excitation coil vibrates the wire at its natural resonant frequency.
When the structure deforms, the wire tension changes, and with it, its vibration frequency. The data logger, or reading device, measures the frequency and converts it into micro-deformation using the calibration factor of each sensor.
The output signal in frequency reduces the influence of the wiring resistance on the measurement.
Applications
- Bridges and viaducts: deformations during construction, load testing, rehabilitation and operation.
- Concrete and masonry dams: monitoring of structural behavior.
- Tunnels and underground works: linings, supports and voussoirs.
- Piles and deep foundations: deformations during load tests.
- Diaphragm walls and retaining structures: response to soil pressure.
- Dovetails and prefabricated elements: sensor integrated into the concrete during manufacturing or installation.
- Metal structures: beams, struts, supports, forced pipes and elements subjected to tension, compression or bending.
Available versions: EDS-20V-AW, EDS-20V-E and EDS-21V-SW
- EDS-20V-AW: Surface mounting by arc welding on metal structures. It can also be installed on concrete using specific anchor blocks.
- EDS-20V-E: Installation embedded directly in fresh concrete. For piles, deep foundations, diaphragm walls, dams, precast segments, and concrete structures where internal deformations are measured.
- EDS-21V-SW: Compact version for surface mounting using spot welding or structural adhesive. For confined spaces or for installation on metal elements, struts, plates, pipes, or existing structures.
Construction, temperature and compatibility
Stainless steel construction with double O-ring seal and heat shrink tubing. IP67 protection rating (IEC 60529).
Integrated thermistor YSI 44005 or equivalent (3000 Ω at 25 °C) to record the temperature at the measurement point and apply thermal compensations.
Compatible with handheld reading units, data loggers, and data acquisition systems for vibrating wire sensors. Communication can be wired or wireless (radio, 4G, Ethernet, or Industrial IoT), depending on the acquisition system. This allows for historical data logging and the setting of alarm thresholds.
Main technical features
- Measurement range: ±1500 µε in EDS-20V-AW and EDS-20V-E; ±3500 µε in EDS-21V-SW.
- Resolution: 1 µε.
- Active length: 150 mm (EDS-20V-AW and EDS-20V-E); 50mm (EDS-21V-SW).
- Output: frequency using vibrating string technology.
- Thermistor: YSI 44005 or equivalent, 3000 Ω at 25 °C.
- Operating temperature: −20 °C to +80 °C.
- Protection rating: IP67.
- Cable: 4-conductor shielded cable, standard length 1 m (other lengths available).
- Material: stainless steel.
Frequently asked questions about vibrating wire extensometers
What is a vibrating string extensometer used for?
It measures deformations in structural elements made of concrete or steel. These measurements are used to evaluate structural behavior, stress state, and the evolution of the infrastructure.
When is an embedded extensometer used?
When the sensor is integrated into the concrete during construction: piles, foundations, walls, dams, slabs, tunnel segments and prefabricated elements.
When is a surface extensometer used?
On existing structures or metal elements where the sensor cannot be installed within concrete. It is fixed by welding, anchor blocks, spot welding, or structural adhesive, depending on the model.
Can it connect to a datalogger?
Yes. It connects to handheld readers, data loggers, and automatic monitoring systems for periodic readings, historical data, and alarms.
What is the difference between a vibrating string and an analog signal?
The vibrating string delivers a frequency signal, which is less affected by the resistance of the wiring and by electromagnetic interference.
Properties
Technical specifications
| Parameter | EDS-20V-AW | EDS-20V-E | EDS-21V-SW |
|---|---|---|---|
| Measuring range | ±1500 µε | ±1500 µε | ±3500 µε |
| Precision1 | ±0.1 % FS. | ±0.1 % FS. | < ±0.25 % FS. |
| Nonlinearity | < 0.5 % FS. | < 0.5 % FS. | < ±0.25 % FS. |
| Resolution | 1 µε | 1 µε | 1 µε |
| Active length | 150 mm | 150 mm | 50 mm |
| Effective gauge factor2 | ≈ 4.051 × 10-3 µε/Hz² | ≈ 4.051 × 10-3 µε/Hz² | ≈ 3.896 × 10-4 µε/Hz² |
| Exit | Frequency (VW) | Frequency (VW) | Frequency (VW) |
| Thermistor type | YSI 44005 or equivalent (3000 Ω at 25°C) | YSI 44005 or equivalent (3000 Ω at 25°C) | YSI 44005 or equivalent (3000 Ω at 25°C) |
| Operating temperature | -20 °C to +80 °C | -20 °C to +80 °C | -20 °C to +80 °C |
| Storage temperature | -20 °C to +80 °C | -20 °C to +80 °C | -20 °C to +80 °C |
| Relative humidity | 0–100 % HR | 0–100 % HR | 0–100 % HR |
| Degree of protection | IP67 (IEC 60529) | IP67 (IEC 60529) | IP67 (IEC 60529) |
| Life of fatigue | 105 cycles at 2500 µε | 105 cycles at 2500 µε | 105 cycles at 2500 µε |
| Wire | 4-conductor shielded cable, standard length 1 m (other lengths available) | 4-conductor shielded cable, standard length 1 m (other lengths available) | 4-conductor shielded cable, standard length 1 m (other lengths available) |
| Dimensions | 174 × 28.5 × 30 mm | 170 × 28.5 × 30 mm | 64.5 × Ø8 mm |
1 Values determined under laboratory conditions.
2 The actual gauge factor value is listed on the calibration certificate supplied with each sensor.
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