1.0 OBJECTIVE 1. To observ e the indu ctive d isplacement sen sor ch aracteri stic. 2. To observ e the capacit ive d isplacement sen sor ch aracteri stic. 2.0 INTRODUCTION Displacement measurement is basic of measuring position, velocity, pressure, stress, force and etc. There are several types of displacement sensors such as inductive displacement sensors and capacitive displacement sensors. An inductive displacement sensors consist of a magnetic circuit made from ferromagnetic core with a coil would on it. The coil act as a source of magnetomot ive force that drives the flux through magnetic circuit and the air gap. The presence of the air gap causes a large increase in circuit reluctance and a corresponding decrease in a flux. Hence, a small variation in the air gap results in measurable change in inductance. inear variable differential transformer !" DT# Th e li ne ar va ri able di ff erenti al tr ansf or me r ! "DT# !als o call ed $u st a di ff erenti al transformer , linear variabl e dis placement tra nsf ormer, or linear var iable dis pla cement tr ansducer# is a type of el ect ri cal transformeruse d for mea suri ng linear dis plac eme nt !position#. A counterpart to this device that is used for measuring rotary displacement is called a rotary variable differential transformer ! %"DT#. 1 Cutaway view of an LVDT is driven through the primary coul at A, causing an induction current to be generated through the secondary coils B
