If the soft iron magnetic core armature is exactly in the centre of the tube and the windings, “null position”, the two induced emf’s in the two secondary windings cancel each other out as they are 180o out of phase, so the resultant output voltage is zero. As the core is displaced slightly to one side or the other from this null or zero position, the induced voltage in one of the secondaries will be become greater than that of the other secondary and an output will be produced.
The polarity of the output signal depends upon the direction and displacement of the moving core. The greater the movement of the soft iron core from its central null position the greater will be the resulting output signal. The result is a differential voltage output which varies linearly with the cores position. Therefore, the output signal has both an amplitude that is a linear function of the cores displacement and a polarity that indicates direction of movement.
The phase of the output signal can be compared to the primary coil excitation phase enabling suitable electronic circuits such as the AD592 LVDT Sensor Amplifier to know which half of the coil the magnetic core is in and thereby know the direction of travel.
đang được dịch, vui lòng đợi..