The Keyphasor is a transducer that generates a voltage pulse for each shaft revolution. This key phasor signal is generally used to determine rotating shaft speed and as a reference for determining vibration phase lag angle.
It’s crucial for determining rotor slow roll bow or runout information. A proximity probe (recommended for permanent installations where the probe observes a physical gap change event), an optical pickup (used for temporary installations where the pickup observes a change in reflectivity event), or a magnetic pickup are the most common Keyphasor transducers.
Keyphasor
A transducer, usually an eddy current proximity measurement, provides the key phasor signal, which is a once-per-turn voltage pulse.
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A key phasor is an electronic pulse or trigger that originates from a location on a spinning shaft and acts as a zero phase reference for determining where rotor imbalance exists.
In turbomachines, the key phasor is required to determine the phase angle of the unbalance mass during dynamic balancing.
Vibration probes can be used to monitor machine health, but if you want to investigate the cause of machine failure, you’ll need a three-dimensional graph that shows/analyses vibrations at any moment in time while the machine is functioning. If you don’t install the keyphasor, you’ll notice that the machine is vibrating, but you won’t be able to pinpoint where the vibrations are coming from, what direction they’re coming from, or what point they’re coming from.
Monitoring, diagnostic, and management systems use the Keyphasor signal to generate filtered vibration. Amplitude, phase lag, speed, and a range of other data points are all useful.
The phase is an important aspect of this data. Overall machine condition and machine defects would be difficult to diagnose without phase information.
The shaft’s reference point is the Keyphasor, which ranges from 0 to 360 degrees. When performing the analysis, it’s critical to pay attention to the 1X and 2X signals, where X refers to the machine’s running speed. The monitors read overall vibration signals at all frequencies, and the speed is calculated using the Keyphasor.
For example, Measurement of the temperature within a heat-producing machine, can provide useful information. When reference temperature conditions, to which the results of the monitoring can be compared, are available, this can be done efficiently. When the temperature rises significantly above what should be the ideal range, it may indicate the emergence of a problem within the machine. –
On the other hand, the temperature may continue to fall below the reference level, which should be sufficient grounds for the engineer or operator to order a machine inspection and maintenance.
Furthermore, machines with rotating parts can be subjected to condition monitoring in order to avoid serious damage, which could necessitate more money in parts replacement and cost plants millions of dollars in lost revenue.
The vibrations produced as the parts spin around at hundreds of revolutions per minute are known to be a valuable means of monitoring these systems for possible damage. Before an accurate prediction of the machine’s state can be made in these systems, the recorded vibrations should be compared to those recorded when the machine was at its best.
Though specialised instruments have been designed to make the process of monitoring the machine for changes in frequency, period, and harmonics easier, the data obtained in most cases is quite complex, and it may take an expert in the field of physics or engineering some time to come up with a logical explanation as to what could be going on inside the machine.
As a result of this issue, technological innovation has resulted in the development of systems that monitor and then interpret the data obtained. It is much easier for the operator to recognise the shifting trend of the machine’s behaviour as these rotating parts wear out over time in such circumstances. As a result, the machine operator is in a good position to alert management to the need to replace worn out parts.
The result of monitoring the machine does not always imply that a portion or parts of the machine are likely to fail totally. As a result, the operator or the person in control of the machine can use more effective methods of monitoring the machine’s development.
The application of the keyphasor principle is an extra measure that can be taken. Any instrument that operates on the keyphasor concept is referred to as a keyphasor. The keyphasor essentially times the machine’s primary shaft; each time the shaft rotates, crucial information regarding the machine’s life is generated. The keyphaser has the ability to transfer one form of energy to another as a transducer. This is why, according to the keyphasor’s principle, the keyphasor can extract mechanical energy from the machine shaft and convert it to a voltage pulse.
The signal from each voltage pulse is an essential component in determining the shaft’s total speed. Depending on how it is utilised, the keyphasor can be divided into three groups. It could be permanently installed in a machine and function as a proximity transducer. It can also be used as a transducer for magnetic pickup or as a more transient optical pickup.
Advantages :
More than a third of the information on the machine’s status is generated by the Keyphasor signal.
- Detection of shaft cracks
- Detection of Rub
- Balancing the Shaft
- Detection of shaft/structural resonance.
