Digital vibration meterThere are various types of sensors, which can be classified into the following categories based on their working principles and measurement parameters:
1、 Classified by working principle
Eddy Current Transducer
Principle: By utilizing the eddy current effect, the vibration displacement or amplitude is determined by measuring the distance change between the sensor end and the measured object.
Features: Non contact measurement, wide frequency range (usually covering 0-10kHz and above), large linear working range, high sensitivity, but small linear range, requiring a dedicated bracket for installation.
Applications: Static displacement measurement, vibration displacement monitoring (such as rotating machinery shaft vibration), metal surface vibration measurement.
Electric (magneto electric) sensor
Principle: Based on the principle of electromagnetic induction, a moving conductor cuts magnetic field lines in a fixed magnetic field, generating an electromotive force proportional to the vibration velocity.
Features: Relative sensor, requiring a fixed reference, output voltage proportional to speed, high sensitivity, but with a small measurement frequency range (usually 0.5-1kHz), susceptible to electromagnetic interference.
Application: Measurement of medium frequency vibration velocity (such as motor and bearing vibration).
Piezoelectric sensor
Principle: By utilizing the positive piezoelectric effect of piezoelectric crystals, charges are generated on the surface of the crystal when subjected to external forces, and the amount of charge is proportional to the vibration acceleration.
Features: Inertial sensor, small size, light weight, high sensitivity, wide frequency range (0.1Hz~30kHz), but requires a matching charge amplifier.
Application: High frequency vibration acceleration measurement (such as shock and vibration fault diagnosis).
Capacitive sensor
Principle: Measure vibration parameters by changing the capacitance gap or common area.
Classification:
Variable gap type: measures linear vibration displacement.
Variable common area formula: measures torsional vibration angular displacement.
Characteristics: Non contact measurement, high sensitivity, but affected by the dielectric properties of the medium, requiring an external power supply or parametric converter.
Application: Precision displacement measurement (such as micro vibration monitoring).
Inductive sensor
Principle: Based on the principle of electromagnetic induction, convert mechanical vibration parameters into changes in inductance.
Classification: Variable gap type, variable magnetic conductivity area type.
Features: Simple structure, but low sensitivity and narrow frequency range.
Application: Low frequency vibration displacement or velocity measurement.
2、 Classified by measurement parameters
displacement sensor
Principle: Measure the vibration displacement of an object and convert it into an electrical signal through the relative motion between the inertial mass and the base.
Characteristics: Absolute measurement, fixed on the object being measured, with a narrow frequency range (usually 0-1kHz), but can directly display displacement amplitude.
Application: Large equipment shaft displacement monitoring (such as turbine vibration).
speed sensor
Principle: Measure the vibration velocity of an object and generate an electrical signal proportional to the velocity through electromagnetic induction or the motion of an inertial mass.
Features: Intermediate frequency measurement (usually 10Hz~1kHz), low output impedance, high signal-to-noise ratio, but large size.
Application: Motor and bearing vibration speed monitoring.
Accelerometer
Principle: Measure the vibration acceleration of an object and generate an electrical signal proportional to the acceleration through the piezoelectric effect or the motion of an inertial mass.
Features: High frequency measurement (usually 0.1Hz~30kHz), small size, high sensitivity, but requires integration conversion to velocity or displacement.
Application: Diagnosis of impact and high-frequency vibration faults (such as gearboxes and bearings).
3、 Classified by installation method
Contact sensors
Characteristics: It requires direct contact with the object being measured, accurate measurement but may affect the vibration state.
Application: Structural health monitoring, equipment vibration testing.
Non contact sensors
Features: No need to touch the object being measured, suitable for high temperature, high speed, or scenarios where contact sensors cannot be installed.
Application: Vibration monitoring and remote vibration measurement of rotating machinery shafts.