Electric motors have had a huge impact on the pump industry.
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Improved motor starters help Fabri-Kal achieve its green vision.
The pump industry is the largest purchaser of electric motors in the United States. According to the U.S. Department of Energy (DOE), electric motors consume more 50 percent of all electrical energy in the United States and more than 85 percent of industrial production electrical energy. Electric motors account for roughly $85 out of every $100 of a manufacturing/process plant's electrical bill.
Last month, we studied the properties and effects of resistive, inductive and capacitive loads in an AC circuit. This month, we will take self induction a step further and apply it to that very simple machine that is at the heart of AC power—the transformer.
All electric motors (motors) have a housing that contains the working components of the motor. In the U.S., the enclosure describes this housing.
Mechanical resonance occurs when an external source amplifies the vibration level of a mass or structure at its natural frequency. For a rotating mass like a motor or a pump, this occurs at the critical speed(s). Electrical resonance amplifies the magnitude of voltage or current, or both.
The Energy Independence and Security Act of 2007 (EISA), which restates and broadens the definition of General Purpose Electric Motors, goes into effect on December 19, 2010. Certain motors "manufactured (alone or as a component of another piece of equipment)" will be required to have nominal full load efficiencies that meet the levels defined in NEMA MG-1 (2006) (see Table 12-12). Motors manufactured after December 19, 2010, must comply with the law.
Introduced February 8, 2008, the RPMAC PM Direct Drive Cooling Tower Motor and VS1CTD Drive for wet cooling towers replaces an existing motor, jack shaft and gearbox with a more efficient and environmentally responsible variable speed motor and drive with the motor mounted directly under the fan.
Latest Motors Articles
Electric motors have had a huge impact on the pump industry.
Improved motor starters help Fabri-Kal achieve its green vision.
The industrial motor world has a new specification available for defining the requirements of general purpose, severe duty motors in the 250- to 3,000-hp range.
Proper alignment of the pump shaft with the driver can reduce vibration and significantly improve reliability. For appropriate applications, the time, expertise and instruments needed to achieve precision alignment (tolerances of less than 0.005 in) will prevent seal leakage and extend bearing life.
Introduced in June 2010, Super-E Motors with AEGIS Shaft Grounding Ring are used in commercial and industrial applications to drive pumps provides a path to ground for circulating currents, preventing bearing fluting.
A paper or an electronic work order system can be used to capture alignment data.
Last September, we spoke about the importance of pipe-to-piping alignment, evaluating actual numbers, and tabulating stress values as they approach yield stress of pipe at various values of misalignment. This time, we will discuss the effects of pump-to-motor misalignment, beyond hype or generalities, by numerically quantifying the conclusions.
A number of choices are available when connecting pumps, fans and other rotating equipment to an electric motor. There are numerous mechanical and fluid coupling designs and, in some cases, a belt drive option is available. Although a belt drive can be more forgiving, all mechanical couplings share the requirement for precise alignment. Since couplings provide a direct physical connection between the motor and the rotating machine, misalignment will create vibration and other stresses that can lead to premature coupling, seal and bearing failure. Misalignment can be due to poor alignment practices or suction and discharge piping stresses.
Editor's Note: Click here to see a sample alignment data form.
Proper alignment of the pump shaft with the driver can reduce vibration and significantly improve reliability. For appropriate applications, the time, expertise and instruments needed to achieve precision alignment (tolerances of less than 0.005 in) will prevent seal leakage and extend bearing life.
Columns and Blogs
In this multi-part series, we will investigate several aspects of centrifugal pump efficiency.
First of Five Parts
Since the original publication of this draft standard in the January 2008 issue of Pumps & Systems, I have received feedback, encouragement, numerous questions and criticism. The draft listed three basic levels of repair.
The McGraw-Hill scientific dictionary [5] states that a volute is "a spiral casing for a centrifugal pump... designed so that speed will be converted to pressure."
