© 2015 Proceq SA 7
3. Tutorial
3.1 The Measurement Principle
The Profoscope uses electromagnetic pulse induction technology to detect rebars.
Coils in the probe are periodically charged by current pulses and thus generate a magnetic field.
On the surface of any electrically conductive material which is in the magnetic field eddy currents
are produced. They induce a magnetic field in the opposite direction. The resulting change in volt-
age can be utilized for the measurement.
Coils
Concrete
Rebar
Magnetic Field
Fig 3: Measurement principle
The Profoscope uses different coil arrangements to generate several magnetic fields. Advanced
signal processing allows
1. Localization of a rebar
2. Localization of the mid-point between rebars.
3. Determination of the
cover
4. Estimation of the bar diameter
This method is unaffected by all non conductive materials such as concrete*, wood, plastics,
bricks etc. However any kind of conductive materials within the magnetic
field
(approx. 400 mm /
16” sphere) will have an influence
on
the measurement.
* Some concrete types and other structural materials may have metallic content.
NOTE! Remove all metallic objects such as rings and watches before you start measuring.
3.2 Calibrated Measuring with Profoscope
The Profoscope is calibrated to measure on a normal rebar arrangement; which is an arrangement
of non-stainless steel rebars fastened with binding wires only. E. g. when measuring on welded
mesh wires the cover and diameter readings must be corrected (see 5.3.3 and 5.4.5). The following
information on accuracy, measuring ranges and resolutions refer to measurements on such normal
rebar arrangements.
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