Webinar recording bundle
A special discounted collection of 9 webinar recordings focusing on a wide variety of vibration, balancing and alignment topics.
Just $45 for EASA members!
This manual covers horizontal and vertical squirrel-cage induction motors in the 300 to 5,000 horsepower range, low- and medium-voltage. Most of the principles covered apply to other sizes as well. This manual focuses primarily on IEC motors and standards.
When it comes to machine vibration, “how much is too much” depends on a number of factors. Knowing which standard and/or tolerance applies requires a working knowledge of the standards and some basics of vibration terminology.
Las versiones impresas, en CD-ROM y en forma de descarga del valioso manual didáctico / recurso de EASA, “Principios de Motores C.A. Medianos y Grandes”, se ahora disponibles en inglés y en español. El manual incluye gráficos e ilustraciones, fotografías y mucha información técnica sobre máquinas C.A., incluyendo como funcionan, información específica sobre los tipos de encerramientos, fabricación de componentes y aplicaciones. Muchos de los principios incluidos en el libro aplican a todos los motores C.A., especialmente a aquellos accesorios que fueron asociados en el pasado con las máquinas más grandes (como encoders, RTDs, termostatos, calentadores de espacio, sensores de vibración, etc.).
Many EASA service centers conduct vibration-based machine condition monitoring programs for their customers. This is a valuable revenue source that aligns the service center as a team member with the customer to provide uptime on their machinery and control maintenance costs. It also puts some of the responsibility for predicting machine failures on service center personnel who may be managing vibration data for hundreds of machines in multiple customer facilities. Given that vibration data is complex, composed of amplitude, frequency and phase, that can be a daunting task.
Muchos centros de servicio llevan a cabo programas de monitoreo por condición basado en la vibración de las máquinas para sus clientes. Esta es una fuente valiosa de ingresos que integra al centro de servicio como miembro del equipo del cliente para garantizar el tiempo de funcionamiento de su maquinaria y controlar los costos de mantenimiento. Esto también pone parte de la responsabilidad de predecir fallos en las máquinas, en el personal del centro de servicio que puede estar gestionando los datos de vibración para cientos de máquinas en múltiples instalaciones del cliente. Dado que los datos de vibración compuestos por amplitud, frecuencia y fase son complejos, esta puede ser una ardua tarea.
The ISO balancing specification for rigid rotors (ISO 1940-1) was innovative when it was introduced decades ago. It established Balance Quality Grades based on the theoretical velocity the mass center of gravity of a rotor would encounter in free space, spinning at the rotor’s normal operating speed. That’s a mouthful of technical jargon, but a practical understanding of the nature of unbalance forces is important in applying balance tolerances to various machine rotors. It is also helpful in understanding the impact of fundamental changes in the recent replacement standard, 21940-11: 2016.
La especificación ISO para balancear rotores rígidos (ISO 1940-1) fue innovadora cuando fue introducida hace varias décadas. Esta norma estableció los Grados de Calidad de Balanceo basada en la velocidad teórica que el centro de masa de un rotor se encontraría en espacio libre, girando a la velocidad de funcionamiento normal del rotor. Esta es terminología técnica difícil de expresar, pero un entendimiento práctico de la naturaleza de las fuerzas de desbalanceo es importante para aplicar las tolerancias de balanceo en rotores de diversas máquinas. Esto también ayuda a entender el impacto de los cambios fundamentales en la reciente norma de reemplazo: 21940-11: 2016.
Trade press article — Maintenance Technology
Vibration readings provide the best early warning of developing problems in a motor or system component. Other parameters to monitor may include operating temperature of critical components, mechanical tolerances, and overall system performance, including outputs such as flow rate, tonnage, and volume.
Knowledge of common vibratory forces helps diagnose and correct problems
Trade press article — Processing Magazine
High vibration is a common problem for motors that are installed on top of vertical pumps. Its source can be a mechanical issue with the pump, motor or coupling or even hydraulic forces from the pump.
FREE for Members of EASA
EASA's most comprehensive technical document is available FREE to EASA members. Download the complete manual or just the sections you're interested in.
This 48-page manual was developed following EASA’s 12-part Vibration for Service Centers webinar series. It serves as an introductory training resource for service center technicians and supervisors involved in measuring, evaluating, and correcting vibration and balancing issues on machines under repair – as opposed to the in-plant predictive maintenance tasks covered in most general classes on the subject.
We’ve covered how to assess impeller damage in a previous presentation. Now learn how to fix that damage.
This 40-page booklet provides a great marketing tool for your service center! Use it to provide end users with information that will help them obtain the longest, most efficient and cost-effective operation from general and definite purpose electric motors.
Este folleto de 40 páginas ofrece una gran herramienta de marketing para su centro de servicio! Lo utilizan para proporcionar a los usuarios finales con información que le ayudará a obtener la, operación más eficiente y rentable de propósito más larga de los motores eléctricos generales y definidas.
EASA’s Recommended Practice for the Repair of Rotating Electrical Apparatus, designated as ANSI/EASA AR100, was first approved as an American National standard in 1998. Since then, it has been revised and approved four more times: 2001, 2006, 2010 and 2015. This article discribes the most recent changes.
This 12-part recording (15 hours) covers a wide range of topics on vibration.
This webinar series was designed to:
- Provide EASA service center technicians with the technical knowledge they need to effectively measure and diagnose vibration on machines being tested in the service center.
- Provide the foundation understanding necessary to use vibration data as an indicator of machinery condition
- Provide the fundamental knowledge of dynamic balancing necessary to use common balancing instruments in the service center
This manual, a companion to EASA's 2-day seminar of the same name, covers horizontal and vertical squirrel-cage induction motors in the 300 to 5,000 horsepower range, low- and medium-voltage. Most of the principles covered apply to other sizes as well. This manual focuses primarily on NEMA motors.
ANSI/EASA AR100 is a must-have guide to the repair of rotating electrical machines. Its purpose is to establish recommended practices in each step of the rotating electrical apparatus rewinding and rebuilding processes.
On occasion, service centers are asked to balance fan blades that are designed for an overhung mounting. The fan blade may be received mounted on the shaft, or without any shaft. The decision has to be made about how to mount the rotor in the balancing machine. One solution is to fabricate a mandrel to balance the fan blade between the machine pedestals. The other alternative is to mount the fan blade on the end of the shaft in an overhung configuration, with the fan blade outboard of both balancing machine pedestals. This would be the more expedient method if the fan blade is already mounted on the shaft in the overhung configuration. How the fan blade is mounted doesn’t change the balance, as long as the fit to the shaft doesn’t change. So the question is, “Which is easiest?” Often it is easiest to mount the rotor in the overhung configuration, but balancing in that configuration presents some challenges. Those challenges are addressed here.
We often hear the terms preventive maintenance (PM) and predictive maintenance (PdM) of electric motors. However, it’s far less often that we give consideration to the tasks associated with these methods of maintaining motor operation and extending operating service life. This article will address some of the more common activities associated with PM and PdM, with the focus on three-phase squirrel cage motors.
Vibration is the most effective and well-recognized parameter for assessing the mechanical condition of electric motors. Generally, lower vibration levels are equated with improved reliability. However, arbitrarily reducing the vibration level specification for acceptance of new and repaired motors will not necessarily result in improved reliability, and it will definitely increase costs. Further, reliance on vibration levels at 2x line frequency (2xlf) as an indicator of electric motor reliability is not effective.
A customer specifies that the rotor is to be balanced to 4W/N. Is that the 4W/N Military specification, or the 4W/N API specification?It could make a big difference. And, how do they compare to the ISO 1940/1 specification (G2.5, G1, etc.)? Fortunately, for symmetrical rotors, comparing the various standards is only a matter of a bit of easy algebra. For non-symmetrical rotors, the process gets a little more difficult because each of the specifications handles these cases differently. The other good news is that there are on-line references that provide graphic and tabulated comparisons.
Vibration has three primary parameters; amplitude, frequency and phase. Previous presentations and papers have focused on the two most common parameters, amplitude and frequency. These two are the primary tools for determining if a machine vibration is a problem, and what the cause of the vibration might be. This paper, presented at the 2013 EASA Convention, focuses on the third parameter: phase angle.
This presentation focuses on:
- Identifying belt vibrartion
- Identifying pulley pitch line run-out vibration
- Other vibration sources
- ODS analysis
There are three fundamental parameters for machinery vibration data: amplitude, frequency and phase. When testing machine vibration, amplitude and frequency are the two primary measurements for acceptance testing and for diagnostics. Both of these parameters have several units in which they can be recorded. Converting from one unit of measurement to another is not difficult if both amplitude and frequency data are available. In many cases, only amplitude measurements are available, without the needed frequency information, so conversion to other amplitude units is not possible. Knowing when conversion is possible and how to a apply conversion formulas is important when assessing customer specifications and analyzing diagnostic data.
This presentation examines:
- How the spectrum is generated from the vibration signal
- The effect of f-max ad resolution settings
- Averaging techniques
- Scaling and demodulation
When machine vibration increases, one of the first questions asked is: "Is a failing bearing causing the vibration?" In the case of rolling element bearings, it is not difficult to separate vibration caused by a failing bearing from other common faults such as unbalance, misalignment, looseness, etc. But sorting out vibration from a failing rolling element bearing (here-after called "bearing vibration") from process sources such as flow induced and background vibration can be more demanding. The secret is to identify the frequency at which a flaw on a roller or raceway will impact the mating bearing component. These are commonly known as bearing fault frequencies.
Topics covered include:
- Simple to complex steps in identifying bearing vibration
- "Locate rpm" function
- Occurance of sidebands
Resonance is a property of all mechanical structures. It can be described as a sensitivity to a certain vibration frequency. For machinery such as electric motors, pumps, turbines, etc., it becomes a problem when small vibratory forces from the machine operation are amplified by mechanical resonance. The result can be very severe vibration levels, even when the exciting forces are small.
When motors are installed on top of vertical pumps, high vibration is a common problem. This presentation provides an understanding of the nature of this style pump and the various forces essential to diagnosing and correcting vibration problems on vertical pump motors.