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What Is A Speed Sensor And What Does It Do?

What Is A Speed Sensor And What Does It Do?

November 28 , 2023 0

Speed sensors are used to measure vibration of non-rotating components such as housing, housing, and foundation. It is a sensor based on the principle of electromagnetic induction. The speed sensor outputs a voltage signal that is proportional to the vibration speed of the object being measured. For those machines whose vibration speed is the monitoring standard, the output voltage of the speed sensor can directly provide data for analysis and processing. For those machines with displacement amplitude as the monitoring standard, it is necessary to integrate the voltage signal so that the output voltage after integration is proportional to the vibration displacement.

What Is A Speed Sensor

A sensor (sensor) is a device that converts a change in non-electrical quantity (such as speed, pressure) into a change in electrical quantity. According to the type of non-electricity converted, the sensor can be divided into pressure sensors, speed sensors, temperature sensors, etc., which are an important part of measurement and control instruments and equipment.
In robot automation technology, speed measurement often focuses on the measurement of rotational motion, while the speed of linear motion is usually obtained by indirect measurement of rotational speed. For example, a tachometer generator can convert rotational speed into an electrical signal, which is a kind of speed sensor. Tachometer generator requires a linear relationship between output voltage and speed, and requires a large output voltage gradient, good time stability and temperature stability. Tachometer generators can generally be divided into two types: direct flow and alternating flow. The excitation mode of the direct-flow tachometer generator is divided into separate excitation type and permanent magnet type, and the armature structure can be in the form of groove, hollow, disk printed circuit, etc., among which the groove type is most commonly used.

How Does The Speed Sensor Work

Speed sensor is a device used to measure the speed of an object, which is widely used in various fields such as automotive industry, aerospace and industrial automation. There are many types of working principles of speed sensors, and several common principles are described below.
Principle of magnetoelectric induction: This principle uses Faraday's law of electromagnetic induction to measure speed through the interaction between a magnetic field and a conductor. The sensor contains a magnetic field source and a conductive material. When the conductive material moves, changes in the magnetic field generate an induced current in the conductive material. By measuring the size of the induced current, we can determine the speed of an object.
Photoelectric sensing principle: This principle uses the properties of light to measure speed. The sensor usually contains a light emitting device and a receiver. A light emitting device sends light, and a receiver receives light. When the object passes by, it blocks the propagation of the beam, causing the intensity of the light signal received by the receiver to change. By measuring the change in the light signal, we can determine the speed of the object.
Acoustic sensing principle: This principle uses the speed of sound waves to measure the speed of objects. A sensor usually contains a transmitter and a receiver inside. The transmitter transmits the sound signal, and the receiver receives the sound signal reflected back. By measuring the travel time and distance of the acoustic signal, we can calculate the speed of the object.
Acceleration sensing principle: This principle is to calculate the speed indirectly by measuring the acceleration of the object. The sensor usually contains an accelerometer, which measures changes in the acceleration of an object in space. By integrating the acceleration, we can get the value of the velocity.

Precautions For Installing A Speed Sensor

Under normal circumstances, the speed sensor is used to measure the bearing vibration, and it can also be used to measure the shaft vibration under specific conditions. In order to ensure the accuracy of the measurement results, the installation of the speed wear angel needs to pay attention to five precautions

1. Working Temperature

The working temperature of the general speed sensor is below 120 degrees, and too high a temperature will cause the sensor insulation damage and demagnetization, reducing its sensitivity. For high and high pressure rotors, when the shaft seal leakage is serious, the sensor can not be installed on the bearing for a long time.

2.Avoid Sensor Fixed Instability And Resonance

No matter which method is used to connect with the bearing, the sensor must be tightly fixed on the object to be measured, and there can be no loosening, otherwise it will cause the impact of the sensor and distort the measurement results.

3.The Position OF The Measurement Point Is Consistent

The bearing vibration of the general unit has a large difference in different positions, so all the use of hand-held, plasticine bonding and permanent magnet suction fixed sensor, should mark the position of the measuring point, to avoid the error due to the different position of the measuring point before and after. This is very important for vibration fault diagnosis and vibration measurement in rotor balance.

4.Sensor Interchangeability

In order to reduce the labor intensity of the test, at present, several to dozens of sensors are generally used to measure the vibration of each point in the unit test. For the same point vibration, when different sensors are used for measurement, the sensitivity and phase characteristics of each sensor should be unified, and only the sensors that have been rigorously tested can be exchanged in the test, otherwise it will cause large measurement errors.

5.The Installation Direction OF The Sensor Is Consistent With The Required Measurement Direction

Bearing vibration is often particularly significant in a certain direction, when the sensor direction slightly deviates from the measurement direction, the meter indicator value will have a large change, especially when the use of hand-held sensors, the sensor is not small skew is often not easy to detect, in addition to the use of plasticine bonding sensor, because the bearing temperature will soften when the plasticine, so that the sensor tilt. And deviate from the measurement direction. Therefore, when measuring vibration, we should always pay attention to the installation direction of the sensor.

Features OF The Speed Sensor

(1) The speed sensor generates voltage output by its own electromagnetic induction, and does not require an external power supply. The speed sensitivity of the output signal is high, the output impedance is low, and the output signal power is strong. Not susceptible to electromagnetic field interference, even in complex field environment, with ordinary cables can be transmitted to a long distance.
(2) The frequency limit of the speed sensor is 1000Hz, which can meet the requirements of the turbine generator set and most rotating machinery for vibration measurement; The disadvantage is that the low frequency performance is poor, and this shortcoming has no great impact on the turbine generator set. For machines operating at speeds below 1000r/min, sensors with lower frequencies (low-frequency sensors) should be selected.
(3) The speed sensor has a large mass, about 300~500g. In order to prevent the sensor from affecting the vibration characteristics of the measured object, it is required that its mass should be less than 1/50 of the mass of the measured object, which can be satisfied for the bearing seat of the turbine generator set and most rotating machinery; For some parts with particularly small mass, the use of speed sensors is not necessarily appropriate.
(4) Simple installation and easy maintenance. Speed sensors are suitable for most rotating machines. Relevant international standards stipulate that for rotating machinery with a speed of 10~200r/s (600~12000r/min), the measurement of bearing seat vibration must use a speed sensor.