Test for repeatability and accuracy at all load level is done at the facility of Dywidag System International. The accuracy is within 1 % to load cell. The sensors are professionally made in a quality controlled facility, and tested individually before sending to the job site.
For the applicability of EM sensor to bridges, EM sensor has passed the fatigue test of 41-strand cable stay system. Force in each 0.6" dia. epoxy coated strand was monitored at various loading stages during 2 million cycles of loading at CTL.
IIS cooperated with the research institute of Hyundai Engineering and Construction, Ltd. (HDEC) had implemented the verification test of the in-situ EM sensor fabricated at HDEC’s research facility at Korea. The parallel wired strand (PWS) cable of 44 meter long and 80 mm diameter installed to the reaction wall is the same size with one of original cables used in the Ma-Chang Grand Bride, cable-stayed bridge. The in-situ EM sensor is fabricated at the arbitrary position over the polyethylene (PE) cover, and an accelerometer is located at a quarter positions.
EM sensor as an alternative to the vibration method has advantages that there is no limitation of geometric conditions such support conditions, length of cable, and sag effect, because the sensor relies on the material property itself on a certain point.