What is the difference between the displacement measurement of a differential voltage transformer se

Satisfactory answer broken sunshine level 6 2009-11-07 asked me to professional differential transformer sensor is two coils in the middle of the iron core (in fact, it is an iron rod), the iron core in the measurement direction to stretch out a measuring head, due to the size of the measured object, the difference in diameter, the measuring head will move back and forth in the measurement direction, thus causing the change of the inductance of the two coils, then take the difference of the inductance of the two coils, through the external wiring of the sensor will convert this change into an electrical signal to the computer, calculated by the computer, The size of the object to be measured is given and the eddy current structure is the simplest, this sensor is inductively measured through a large plane at the bottom, and other transmission and differential transformer sensors are the same, which are also inductive sensors.

Follow-up: I'll add to you: eddy-current sensors are often used to measure vibration displacement. A differential transformer is a mutual inductance displacement sensor.

Due to its high precision, large range (hundreds of millimeters displacement can be measured) and good resolution, it can combine high-frequency excitation power supply, differential rectifier circuit, and filter into a DC differential transformer with small size and light weight.

Asked me professionally.

Due to the difference in the size and diameter of the measured object, the measuring head will move back and forth in the measurement direction, thereby causing the change of the inductance of the two coils, at this time, the difference of the inductance of the two coils is taken, and this change is converted into an electrical signal and transmitted to the computer through the external wiring of the sensor, and the computer calculates and gives the size of the measured object.

The eddy current structure is the simplest, this kind of sensor is inductive measurement through the large plane at the bottom, and other transmission and differential voltage transformer sensors are the same, this sensor is also an inductive sensor.

Approximate classification of displacement sensors.

A displacement sensor is a potentiometer element that converts mechanical displacement into a resistor, voltage, or current output that is linear or arbitrary as a function of it. Both a normal linear potentiometer and a circular potentiometer can be used as a linear and angular displacement sensor, respectively. However, potentiometers designed for the purpose of measuring displacement require a definite relationship between the change in displacement and the change in resistance.

Displacement sensors are divided into the following categories according to different materials:

The movable brushes of the potentiometer displacement sensor are connected to the object to be measured, and the displacement of the object causes a change in the resistance of the moving end of the potentiometer. The change in resistance reflects the magnitude of the displacement, and whether the resistance increases or decreases indicates the direction of the displacement. A supply voltage is usually applied to the potentiometer to convert the resistance change into a voltage output.

The output characteristics of wirewound potentiometers are also stepped due to the fact that the resistance of the wirewound potentiometer changes in turn resistance as the brush moves. If such a displacement sensor is used as a displacement feedback element in a servo system, an excessive step voltage can cause the system to oscillate. Therefore, in the manufacture of potentiometers, the resistance value of each turn should be reduced as much as possible.

Another major disadvantage of potentiometer sensors is their ease of wear. Its advantages are: simple structure, large output signal, easy to use, and low cost.

Hall displacement sensor The measuring principle is to keep the excitation current of the Hall element (see semiconductor magnetocent) unchanged and make it move in a gradient uniform magnetic field, then the displacement is proportional to the output Hall potential. The larger the magnetic field gradient, the higher the sensitivity; The more uniform the gradient variation, the closer the relationship between the Hall potential and the displacement is linear. Figure 2 shows three magnetic systems that generate gradient magnetic fields:

The linear range of the system a is narrow, and when the displacement Z=0, the Hall potential ≠ 0; The b system has good linearity when Z2 mm, and Hall potential = 0 when Z=0;The sensitivity of the c-system is high, and the measuring range is less than 1 mm. In the figure, n and s represent the positive and negative magnetic poles, respectively. Hall displacement sensors have low inertia, high frequency response, reliable operation and long service life, so they are often used in the occasion of converting various non-electric power into displacement and then measuring.

Photoelectric displacement sensor It measures the displacement or geometric size of an object based on how much it blocks the luminous flux. It is characterized by non-contact measurement and continuous measurement. Photoelectric displacement sensors are often used for continuous measurement of wire diameter or as edge position sensors in strip edge position control systems.

Linear rod displacement sensor.

Such as the American Schaevitz brand.

Spring-rebound LVDT displacement.

Measuring sensors.

For example, the American Schaevitz brand and the British LD brand pull wire displacement sensor, such as the American Firstmark brand grating ruler as above for the contact displacement sensor, as well as the non-contact displacement sensor.

Such as magnetostrictive displacement sensors.

Ultrasonic displacement sensors

laser displacement sensors and much more.

Straight rod displacement sensor, such as the American Schaevitz brand spring rebound LVDT displacement measurement sensor, such as the American Schaevitz brand and the British LD brand.

Pull wire displacement sensors, such as the American Firstmark brand grating ruler as above, are contact displacement sensors, and non-contact displacement sensors.

Such as magnetostrictive displacement sensors, ultrasonic displacement sensors, laser displacement sensors and so on.