Bridge Excitation Systems for Civil Engineering Transducers

Types

Amplifiers used in conjunction with civil engineering transducers are available in 2 bridge excitation systems: constant voltage and constant current. These two systems have their respective features shown in the table below, to permit selection according to measurement purposes and applications.
All KYOWA strain gage transducers, including those for civil engineering, are calibrated at the factory using the constant voltage system.

Bridge Excitation System Constant-voltage Bridge Excitation System Constant-current Bridge Excitation System
Civil engineering transducers Measurement of physical quantity possible Measurement of physical quantity possible
T series transducers Measurement of physical　quantity(only engineering quantity) possible Temperature measurement together with physical quantity possible  ※
Applicable gage bridge 60 to 1000Ω 350Ω
Calculation for compensation of declined sensitivity due to cable extension Required Not required
Applications Measurement with cable not extended too long.
Mainly for experimental measurement		 Measurement via extension cable Mainly for field measurement

※T series is provided with temperature measuring function

The reason why constant-current bridge excitation is used for civil engineering measurement with cable extended

If a 100 m long cable with cross-section 0.5 mm 2 is used for connection between a KYOWA civil engineering transducer with bridge resistance of 350Ω and an amplifier of the constant-voltage bridge excitation system, sensitivity declines by approximately 2%. To avoid such inconvenience, it is recommended to use an amplifier of the constant-current bridge excitation system, which ensures measurement with less error.

※For use under corrosive liquid or gaseous environment, contact us

Small to Large-scale Measurement for Deformation Monitoring and Control

Cable Temperature Measurement with T Series Bridge Excitation of Cable Measuring Instrument
Short No Constant voltage
Yes Constant current
Long No Constant current
Yes Constant current

Measurement of Dynamic Phenomena