System for capacitive measurement of inner diameter of electrically conductive materials of center borehole in e.g. air bearings, has supply line establishing connection, where length of line is lesser than hundred times length of electrode

摘要

The system has a capacitance measuring circuit measuring capacitance between a measuring electrode (2) of a measuring head (1) and inside diameter of a center borehole (19). A supply line (19) establishes a connection between the measuring electrode and the capacitance measuring circuit. A part of length of the supply line from a ground potential of the capacitance measuring circuit and/or constant electric potential and/or a shield potential is surrounded on a part of a circumference of the supply line. Length of the supply line is lesser than hundred times an axial length of the electrode. An independent claim is also included for a method for measuring inner diameter of an electrically conductive material.