What is the use of Keyphasor in turbine?
Keyphasor is an electric pulse, or trigger, which is derived from a point on a rotating shaft, it serves as a zero phase reference for determining where imbalance is on a rotor. The keyphasor in turbo machines are necessary to find phase angle of unbalance mass at the time of dynamic balancing.
How many types of condition monitoring are there?
There are two broad techniques in condition monitoring—condition checking and monitoring changes in performance over time. Condition checking assesses the state of a machine at a specific moment in time and takes a performance snapshot, from which to derive its current operational health.
How do you test for Keyphasor?
Mount the keyphasor probe on the driver of the machine train. This will allow the driver to be run while uncoupled from the load. Mount one (1) Keyphasor probe per each machine speed. If a gear increaser or reducer is used, two (2) Keyphasor probes are recommended, one on each side of gear box.
Why is condition monitoring used?
The use of condition monitoring allows maintenance to be scheduled, or other actions to be taken to prevent consequential damages and avoid its consequences. Condition monitoring has a unique benefit in that conditions that would shorten normal lifespan can be addressed before they develop into a major failure.
What is a Keyphasor module?
Keyphasor signal is a once-per-turn or multiple- event-per-turn pulse from a rotating shaft or gear used to provide a precise timing measurement. This allows 3500 monitor modules and external diagnostic equipment to measure shaft rotative speed and vector parameters such as 1X vibration amplitude and phase.
What is gap voltage in vibration?
Gap voltage (VDC) is a direct representation of distance between the probe’s tip and the shaft’s surface. This is the quiescent voltage that needs to be adjusted between the proximitor’s output voltage range limits. Any vibration of the shaft will cause the proximitor’s output voltage to vary in precise step.
What are the 5 elements of condition monitoring?
Condition Monitoring consists of five key elements:
- Site Assessment.
- Fleet management.
- Equipment Inspections.
- Preventative Maintenance.
- Fluid Sampling & Analysis.
What are the basic principles of condition monitoring?
Condition monitoring to help prevent machine failure
Proactive Maintenance – maintaining the machine before failure occurs. Predictive Maintenance – monitoring the condition of the machine and predicting failure early. Reactive Maintenance – maintaining the machine once failure occurs.
What are types of condition monitoring?
9 types of condition-based monitoring that you must know
- Vibration Analysis.
- Motor Circuit Analysis.
- Thermography.
- Ultrasonic Monitoring.
- Laser interferometry.
- Electrical monitoring.
- Electromagnetic Measurement.
What is the disadvantage of condition monitoring?
The disadvantages of Condition Monitoring are as follows.
Short-term investment is required. The equipment for condition monitoring is expensive. The sensors of condition monitoring may not survive depending upon the environment. It exhibits unpredictable maintenance periods.
What is the difference between relative and absolute vibration?
An absolute shaft vibration measurement provides a measure of shaft stresses whereas the relative shaft measurement relates the amount of journal bearing clearance used by vibration and the stress on the Babbitt of the bearing liner.
How many types of vibration sensors are there?
The vibration sensors used in industries can be grouped into the following three primary types: Accelerometers or Acceleration Transducers. Velocity sensors, and. Displacement sensors or Displacement transducers.
Why we use negative voltage in vibration measurement?
Vibration meters use PNP transistors instead of NPN because they are inexpensive. The PNP transistors used by the circuits needed a negative bias voltage rather than a favorable bias voltage.
What is example of condition monitoring?
Common types of condition based monitoring include vibration analysis and vibration monitoring, oil analysis, and temperature tracking and measurement. As we noted above, some the most common types of condition based monitoring look at vibration, oil, and temperature.
What are the instruments used in condition monitoring?
What Instruments Are Used in Condition Monitoring?
- Accelerometers for vibration analysis.
- Velocity sensors for vibration analysis.
- Infrared cameras for temperature.
- Ultrasonic sensors.
- Oil quality sensors.
What does G mean in vibration?
Vibration can be expressed in metric units (m/s2) or units of gravitational constant “g,” where 1 g = 9.81 m/s2. An object can vibrate in two ways: free vibration and forced vibration. Free vibration occurs when an object or structure is displaced or impacted and then allowed to oscillate naturally.
What does RMS mean in vibration?
Root Mean Square value
2. rms（Root Mean Square value） Root mean square value of the instantaneous values in a certain time duration. It relates to the power of the wave. The rms value of velocity is one of the important factors for machinery status diagnosis.
What is the principle of vibration sensor?
Vibration sensor detects the vibration parameter of objects through its mechanical structure, and converting the vibration parameter into the electrical signal by physical effect to achieve transferring the non-electrical signal to electrical signal. …
What is the range of vibration sensor?
Industrial vibration sensors are suitable for measuring vibrations at medium strengths. These sensors have a sensitivity of 100 mV/g and their typical frequency band ranges from 1 Hz to 8000 Hz. At the lower end of the scale, the so-called seismic vibration sensors are built to detect very weak vibrations.
What is PSD mean in vibration?
Power spectral densities
Vibration in the real world is often “random” with many different frequency components. Power spectral densities (PSD or, as they are often called, acceleration spectral densities or ASD for vibration) are used to quantify and compare different vibration environments.
What is PSD in vibration?
In vibration analysis, PSD stands for the power spectral density of a signal. Each word represents an essential component of the PSD. Power: the magnitude of the PSD is the mean-square value of the analyzed signal. It does not refer to the physical quantity of power, such as watts or horsepower.
What is unit of vibration?
■ Vibration Terminology
Important parameters relating to vibration pickups/vibrometers are described below: (1) Vibration frequency Unit: Hz (Hertz) Symbol: f Refers to the number of times a vibrating object vibrates per second. The inverse of a vibration frequency is referred to as the period (T), T=1/f.
What is RMS in vibration?
The RMS (root mean square) value is generally the most useful because it is directly related to the energy content of the vibration profile and thus the destructive capability of the vibration. RMS also takes into account the time history of the wave form.
What does g 2 Hz mean?
The Hz value in [G^2/Hz] refers to a bandwidth rather than to the frequency in Hz along the X-axis. The RMS value of a signal is equal to the standard deviation, assuming a zero mean. The standard deviation is usually represented by sigma σ . A pure sinusoidal function has the following relationship: RMS.
What is FFT in vibration?
The fast Fourier transform (FFT) is an efficient algorithm used to compute a discrete Fourier transform (DFT). This Fourier transform outputs vibration amplitude as a function of frequency so that the analyzer can understand what is causing the vibration.