System Description

The NDU consists of:

• a set of working electrodes (WE) inside the object. If the task is the supervision of the object, at least one WE consists of material identical to the wall material. If the task is to determine which material might be of better use, one WE is of a material similar to that of the wall, and a set of WE of dissimilar materials is used for evaluation of their properties.
• a low - noise potential preamplifier (BUF)
• a low - noise current sink (CS)
• a polarisation control unit (INT), operating on the current sink for periods when the polarisation resistance is to be measured.
• a control unit (SI)

The Evaluation System Consists of:

• an A / D converter unit
• a personal computer
• software basing on Keithley - CEC - Testpoint^TM