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Welcome to Faraday Predictive - specialists in the application of Model-Based Voltage and Current (MBVI) systems

Maintec

New Product Launch

Come and see the new S200 in-cabinet Energy and Condition Monitoring system at Maintec stand 27 – download S200 brochure here

Come and see us on stand 27 to try out the P200 Portable Equipment Health Assessor hands-on – download P100 brochure here

Welcome to Faraday Predictive – specialists in the application of Model-Based Voltage and Current (MBVI) systems for Condition Monitoring and Diagnostics of rotating equipment.

Whether you just want a quick assessment of the condition of one or two machines, or are looking to implement a comprehensive Condition-Based Maintenance strategy, we are here to help you

At Faraday Predictive we are passionate about the application of condition monitoring to the extent that it is all that we do. Through years of experience, we know that predicting failure is the best maintenance approach but that it has been difficult to achieve because of the complexity and costs of Condition Monitoring techniques... until now.

MBVI, coupled with the Faraday Predictive diagnostic algorithms, is not only easier to use than other condition monitoring systems but also can identify a wider range of problems and potential faults than conventional techniques.

Through our range of permanently installed or portable solutions and services we can help you to:

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What is MBVI?

MBVI is the acronym for Model-Based Voltage and Current – MBVI rather than MBVC, because I is the standard symbol for representing electric current.

MBVI systems are a powerful condition monitoring and diagnostic technique for equipment driven by electric motor.

MBVI systems use the motor as a sensor to identify a wide range of phenomena in both the motor and the driven equipment, in the mechanical and operational domains as well as electrical.

MBVI systems measure the voltage and current drawn by the motor, and do not need sensors fitting to the rotating equipment itself. These measurements are normally made in the motor starter cabinet, avoiding the cost and complexity of fixing accelerometers to each bearing, avoiding costs of cabling, and avoiding the risk of mechanical damage to the sensors.

MBVI systems build a model of the relationship between Voltage and Current (hence the M-B of Model - Based). This model is used to identify the distortions on the current waveform that have not been caused by distortions on the voltage waveform – and which therefore must have been caused by the behaviour of the motor and driven equipment.

MBVI systems can be supplied either for permanent installation or as a portable kit that can be connected temporarily to give a quick assessment of the condition of the equipment.

Faraday Predictive can supply all these types of system and can also provide an on-site assessment and diagnosis service, allowing you to put a “toe in the water” to discover the depth of information available about the condition of your own equipment, and giving you a report on the condition of several of your items of equipment.

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How do MBVI systems work?

The Concept: MBVI systems work on the principle that the current drawn by an electric motor is affected by not only the applied voltage but also the behaviour of both the motor and the driven equipment. MBVI systems identify the distortions of the current waveform that have not been caused by distortions on the voltage waveform and therefore must have been caused by the behaviour of the motor and driven equipment system. The frequency of these distortions indicates the nature of the cause, and the magnitude of the distortions indicates the severity of the cause.

The Practice - detecting bearing problems for example: Most people are familiar with the idea that putting more load on a motor causes it to draw more current, and conversely putting less load on a motor causes it to draw less current. A varying load will therefore result in a varying current, where the current goes up and down at exactly the same time that the load goes up and down. For the motor, the load is felt as the torque required to turn the shaft. So variations in torque will result in variations in the motor current.

In the case of a shaft rotating on rolling element bearings, as the bearing starts to deteriorate, it results in a varying torque requirement to drive the shaft. If you ever try to turn a shaft which has bearing problems with your fingers, you will experience that it feels “lumpy” as the balls or rollers roll over damaged areas of the bearing races - effectively your fingers are acting as torque sensors, detecting the variations in torque required to rotate the shaft. These variations in torque occur at well understood multiples of shaft speed, with specific frequencies corresponding to the rolling elements impacting with defects on the inner race or the outer race for example. Standard tables are available that set out the characteristic frequencies for each particular type of bearing, and these are widely used in conventional Vibration Analysis. Exactly the same data are used by MBVI systems. Rolling element bearing problems will show up as peaks on a spectrum at their particular characteristic frequencies, allowing them to be identified as either inner race, outer race, train, or ball-spin problems.
The height of these peaks indicates the severity of the damage.

For more information on MBVI and other condition monitoring systems, see Wikipedia page on condition monitoring: https://en.wikipedia.org/wiki/Condition_monitoring

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What faults can MVBI detect?

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What parameters do MBVI systems measure?

MBVI systems only directly measure Voltage and Current and from this are able to calculate and display:

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How MBVI compares with MCSA?

MCSA (Motor Current Signature Analysis) is a well-established technique that relies on the same fundamental principle as MBVI systems, that the current drawn by a motor is affected by a number of factors, that each occur at specific, identifiable frequencies. MCSA is classically used for identifying rotor-bar problems in induction motors – a phenomenon that MBVI systems can also identify, with generally better resolution than MCSA.

However, MBVI systems are much more powerful than MCSA at identifying and diagnosing a wide range of phenomena. The key differences between MBVI systems and MCSA systems are:

How MBVI compares with Torque Spectrum?

MBVI systems generate a spectrum of the residual current - ie the distortions on the current waveform not caused by the voltage supply. This signal contains information about a number of different features. Although the description about detecting bearing faults in the section above uses the example of bearing faults leading to changes in torque on the motor, there are many other factors that can affect the motor current, including eccentric rotor, varying air-gap between rotor and stator, distortion of the motor frame etc, and all of these factors reveal themselves in the residual current spectrum.
By contrast, a simple torque spectrum only shows the torque. The two spectra, if laid on top of one another, can generally be seen to be noticeably different.
Torque spectrum is prone to distortion effects if the voltage waveform is distorted – something the model-based approach removes. This would suggest MBVI systems are better suited to situations where the voltage supply is distorted, such as on inverter driven equipment.

How MBVI compares with VA?

Compared to Vibration Analysis, MBVI systems are more sensitive to torsional phenomena, whereas Vibration systems are more sensitive to radial phenomena. MBVI systems can detect a wide range of mechanical phenomena inside the motor and driven equipment, not only related to bearings but also to common issues such as misalignment and rubbing. MBVI systems also detect a range of electrical problems such as broken rotor bars and loose motor windings.
MBVI systems measure a range of electrical parameters such as Total Harmonic Distortion (THD), Voltage Imbalance and Current Imbalance that can themselves contribute to longer term mechanical as well as electrical problems. These parameters can also give rise to vibration signals, that can sometimes be misinterpreted by Vibration Analysis as mechanical faults such as bearing problems. Because these electrical parameters are being directly measured by MBVI systems, such false diagnosis can be avoided.
As with Vibration Monitoring, the signals identified by MBVI systems increase when the equipment is working under greater load. Just using the increased vibration levels only, one might falsely conclude that a problem was developing. Because MBVI systems measure Voltage and Current, they also calculate power, and use this load information to normalise readings to avoid such false diagnoses.
MBVI systems also measure basic parameters such as Power, Power Factor, number of starts etc

How can I get started with MBVI systems?

MBVI systems offer the biggest benefit when they are permanently installed, since they offer 24 x 7 monitoring of your equipment, and allow you to see trends as faults develop, allowing for better prediction of problems, and allowing you to measure energy consumption, number of motor starts, total run hours, etc. Simply let us know the details of the equipment items you want to monitor and we’ll send you a quote for the complete solution.

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If you are not yet ready for a permanent installation, or want a quicker answer and don’t want to wait for a permanent installation to be completed, MBVI portable systems such as the Faraday Horizon Portable kit picture required can provide an easier route into the world of MBVI diagnostics. This kit provides a snap-shot of equipment condition giving you a rapid insight into a wide range of possible equipment faults – including mechanical, electrical and operational problems.

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MBVI, coupled with the Faraday Predictive diagnostic algorithms, is not only easier to use than other condition monitoring systems but also can identify a wider range of problems and potential faults than conventional techniques.
MBVI, coupled with the Faraday Predictive diagnostic algorithms, is not only easier to use than other condition monitoring systems but also can identify a wider range of problems and potential faults than conventional techniques.

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And if you just want to get some rapid results without having to invest in the portable kit yourself, Faraday Predictive can come and carry out the tests for you. Our standard service is to spend one day on site, during which we can carry out tests, and provide reports, on as many motors as you can make available in the time. Depending on your operation, your electrical operating procedures, and the electrical connections available, this could be between 4 and 12 items of equipment.

And if all of the above sounds interesting but you are not yet sure which approach is best for you, please give us a call on the number below. We look forward to talking with you!

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