← Volver a la categoría Drives & Motors

Los acoplamientos de imanes permanentes y la tecnología de discos de velocidad ajustables reducen su costo total de propiedad

Acoplamientos magnéticos

Motor Couplings are used throughout all process industries utilising rotating equipment. While the most basic function of these couplings is to transfer torque between the motor and the driven load; coupling manufacturers have expanded their product scope to address the common issues of misalignment, vibration, and torque pulsations. While the available coupling technologies have been fairly successful at addressing these issues, this expanded scope of operation has, in many cases, increased the maintenance and operating costs of the systems in which they are used. The introduction of Permanent Magnet Couplings (PMC’s) that transmit torque across a gap of air has changed the coupling paradigm. The “Disconnected Connection” offered by PMC’s physically separates the motor from the load resulting in significant reductions in vibration. This reduction in vibration has resulted in large savings in maintenance & operating costs not possible with other technologies.

Los acoplamientos de ejes giratorios vienen en muchas configuraciones diferentes. Cada tipo ofrece diferentes construcciones que están diseñadas para cumplir con demandas de procesos variables. La elección del tipo de acoplamiento que se utilizará tendrá un impacto significativo en el rendimiento de los procesos y en el costo de mantenimiento y funcionamiento del equipo del proceso. Los estudios de campo han demostrado que hasta un 70% de todas las fallas en los rodamientos y un 80% de todas las fallas en las juntas son causadas por una vibración excesiva. La vibración excesiva generalmente es el resultado de la desalineación entre el motor y su carga accionada.

Con demasiada frecuencia, cuando un acoplamiento falla en la operación, se reemplaza inmediatamente por otro acoplamiento del mismo diseño y configuración. Desafortunadamente, este enfoque ignora el hecho de que el acoplamiento anterior puede haber fallado porque no era adecuado para la aplicación.

Cuando se considera el Costo total de propiedad (TCO) a largo plazo para todo el sistema en el que se utiliza el acoplamiento, a menudo resulta obvio que el reemplazo en especie no es el enfoque correcto. Elegir el acoplamiento adecuado para la aplicación no solo alargará la vida útil del acoplamiento, sino que también aumentará la vida útil de los rodamientos, sellos, ejes y otros componentes rotativos del equipo.

Al realizar una compra de acoplamiento, es importante observar el TCO asociado con cada una de las opciones disponibles. El análisis de TCO debe incluir todos los costos que acompañan a cada opción. El precio de compra inicial normalmente solo alcanza el 10% de TCO. Controle la eficiencia energética del sistema, los costos de operación del sistema no energético (como los requisitos de mantenimiento a largo plazo), la vida útil del sistema de accionamiento y el costo del tiempo de inactividad del proceso, todos deben participar en la decisión de compra. Algunos de estos, como el precio inicial, son fáciles de manejar. Sin embargo, los costos de mantenimiento y reparación del acoplamiento a largo plazo tienden a ser un poco más difíciles de cuantificar cuando se comparan las opciones disponibles.

Acoplamientos de imanes permanentes.

The introduction of Permanent Magnet Couplings (PMC’s) by MagnaDrive Corporation, distributed in the UK and Ireland by Drive & Couplings Solutions Ltd, has given the process industry another option to consider when reviewing technologies available to transfer torque between a driver and load.

Figure 1 – Permanent Magnet Coupling

PMC‘s consist of two primary components. The first component, a set of copper conductor plates is connected to the motor shaft; the second component of the permanent magnet drive is a rigid assembly of permanent rare earth magnets, which are connected to the load. During operation, relative motion between these parts creates an interwoven eddy current field that transmits torque across the air gap between the magnet and conductor rotors. During operation no physical connection exists between the motor and the load. This “disconnected connection”, exclusive to PMC’s has demonstrated vibration reductions up to 85% when compared to other torque transfer technologies.


Figure 2 – Permanent Magnet Coupling Cross- Section

PMC’s can be used on most rotating equipment applications with the current technology able to handle up to 4 Megawatt loads. The eddy currents being produced in a PMC are created by relative motion, called “slip”, between the conductor rotors and the magnet rotors. In a typical PMC, this slip results in an approximate speed loss of 1% – 2%.

Because PMC’s operate without any physical connection between the driver and its load, these couplings are able to tolerate angular misalignment of 2 degrees with standard designs and up to 4 degrees utilising standard coupling modifications, parallel misalignment of 6.35 mm is allowed and axial shaft movement of 3.175 mm is well tolerated, with no loss in efficiency.

PMC’s also offer the option of characterising the start-up torque curves to meet individual process needs. Field adjustment of a PMC is accurate and repeatable. The transfer of torque between the magnet and conductor rotors is based on physical laws related to the strength of the magnets and the distance between the magnets and the conductors.

PMC’s offer the option of providing over-torque protection. Utilising the physical property that a rapidly moving conductor will repel a stationary magnet, the range includes a torque limiting coupling that magnetically decouples the driver from the load in an over-torque event. No damage is done to the driver, the load, or the coupling and resetting the coupling is as simple as stopping the motor, clearing the load, and then restarting the system.

Debido al arranque acolchado desconectado, el motor no necesita superar la inercia de la carga, la Corriente de demanda máxima y la duración de la Inrush se reducen significativamente. Este inicio amortiguado da como resultado un ahorro de energía (consulte el gráfico a continuación) y un desgaste reducido del equipo. Para muchas aplicaciones, una corriente de menor demanda también puede contribuir a reducir las tasas de energía eléctrica. Además, el espacio de aire del Acoplamiento se puede ajustar durante la instalación para operar una bomba, ventilador o soplador a un flujo menor que el máximo, con un considerable ahorro de energía basado en las Leyes de Afinidad centrífugas.

Graph 1 – Energy Saving Coupling Comparison

PMC’s use no bearings or seals in their design and have no wearing components. As a result, no lubrication of any kind is required. The only maintenance recommended by the manufacturer is a periodic check of the coupling’s air gaps to ensure that proper spacing is maintained. Add to this the fact that the magnets themselves have a half-life of over 2000 years and clearly the cost associated with maintaining these couplings will be very low!

Imán permanente Impulsiones de velocidad ajustable.

Much attention is paid to the energy efficiency of Variable Speed Drive (VSD) technologies. Energy efficiency is only the “tip of the iceberg” when considering the TCO of VSD alternatives. End users of VSD’s need to consider the costs associated with maintaining, repairing, and operating the variable speed control technology they decide to use in their plant. The differences in the costs of replacing parts, repairing vibration caused damage, correcting misalignment, and replacing worn out or obsolete VSD components can be considerably higher than the energy cost differences between the same technologies.

Permanent Magnet Adjustable Speed Drives (PMASD’s) by MagnaDrive Corporation, distributed in the UK and Ireland by Drive & Couplings Solutions Ltd, has given the process industry another option to consider when reviewing adjustable speed applications.

PMASD‘s as with the PMC’s consist of two primary components. A set of copper conductor plates and an assembly of permanent, rare earth magnets. To adjust the speed of the driven load, the amount of torque transmitted from the motor to its load is controlled by changing the distance between the conductor plates and the magnet assembly. During operation and throughout the entire speed range, no physical connection exists between the motor and the load. This “disconnected connection” has demonstrated vibration reductions up to 85%.



Figure 4 – Permanent Magnet Adjustable Speed Drive

PMASD’s can be used on any centrifugal load application with the current technology able to handle up to 3 Megawatt loads. Because the speed of the load is changed while allowing the motor to continuously operate at its nameplate speed, motor heating and the resulting inefficiencies are not an issue. Also, because the permanent magnet drives are mechanical devices, they do not introduce harmonics into the user’s power grid. Filters, transformers, and air conditioning systems are not necessary.

The advantage of PMASD’s is found in the fact that they operate without any physical connection between the driver and the load. By completely isolating these components from each other, PMASD’s eliminate the alignment-related issues experienced by all traditional VSD technologies. The result is increased seal and bearing life in the overall system and a reduction in the cost of operating and maintaining that system over its life.

En resumen.

The potential value of permanent magnet technology is clear. The permanent magnet concept for PMC’s and PMASD’s has been proven across all industries. The use of permanent magnet drives can result in significant energy and non-energy operational savings with annual non-energy operating costs as low as 3% of initial installed costs.

Drive & Coupling Solutions Ltd
Windemere, Cumbria

Puede ser contactado en:

Tel: 01539 442252
E - mail: book.equilibrium@gmail.com
Web: www.driveandcouplingsolutions.co.uk

Informador de la industria de procesos

Noticias relacionadas

Deje un comentario.

Su dirección de correo electrónico no será publicada. Los campos necesarios están marcados *

Este sitio usa Akismet para reducir el correo no deseado. Descubra cómo se procesan los datos de sus comentarios.