Nikhil Sharma
Table of Contents
Vibration tracking/monitoring is the process of searching for abnormalities and tracking changes in a system’s vibration signal. Changes in intensity, amplitude, and frequency define the vibration of any moving object. These vibration characteristics can be linked to physical processes, allowing vibration data to be used to acquire insight about equipment health.
Various sensors are used in vibration monitor:
Velocity Sensors
Electromagnetic linear velocity transducers
It’s most commonly used to calculate oscillatory velocity. An emf is created by a permanent electromagnet traveling back and forth inside a coil wound. This emf is related to the magnet’s rotation velocity. This magnetic force can be used to detect the velocity of a vibrating object.
Electromagnetic tachometer generators
Vibrating objects’ rotational velocity is measured with this instrument. They generate a proportionate output voltage/frequency based on the rotational acceleration. AC tachometers employ a changeable coupling converter with a connection coefficient proportionate to the rotor speed, whereas DC tachometers use a magneto or permanent magnet.
Acceleration Sensors
- Capacitive Accelerometers
Typically used with 1 or 2 two static electrodes as well as a diaphragm-supported seismic weight as a dynamic electrode. The signal created by the capacitance shift when it comes to vibration monitoring is post-processed with LC circuits and other devices to produce a quantifiable entity.
- Piezoelectric Accelerometers
The force of acceleration exerted on a seismic weight act on the piezoelectric crystals, causing a proportionate electric charge to be produced. The voltage created by piezoelectric crystals is frequently preloaded, because a change in acceleration produces a shift in the voltage generated by them. However, they are unreliable at extremely low frequencies.
- Potentiometric Accelerometers
It’s fairly inexpensive and can be used to detect gradually varying acceleration with a decent amount of precision.
A spring mass system’s movement is physically connected to a viper arm that moves over a potentiometric resistance element in these. Viscose, magnetic, or gas damping can be used in different design.
- Reluctive Accelerometers
They are made up of difference transformer or capacitance bridging accelerometers. The phase and amplitude of these devices’ AC outputs varies. A phase-sensitive demodulator is used to convert them to DC.
- Servo Accelerometers
Close precision is achieved by sealed loop servo circuits such as torque-balance, force-balance, or null-balance. A seismic body moves when it is accelerated. One of the motion-detection sensors detects motion and generates a pulse that serves as an error function in the servo-loop.
The demodulated and boosted signal is then supplied to the torquing coil placed near the mass’s rotational axis via a passively dampening network. The momentum is related to the coil current, which is equal to the torque.
Proximity Sensors
Eddy Current Sensor Probe
When a flowing (or shifting) magnetic force contacts a wire, or vice versa, eddy currents arise. Within the conductor, the comparative velocity creates a revolving movement of electricity, or currents. Permanent magnets with electromagnetic field that counter the action of the supplied magnetic field are created by these circular current eddies.
The more the currents created and the higher the oppositional field, the larger the induced magnetic field, the higher the electrical permeability of the conductor, or the better the comparative velocity of motion. Eddy flow probes detect the creation of auxiliary fields to determine the probe’s distance from the material surface.
