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.
When a motor fails, users can (1) rewind, possibly for high efficiency; (2) replace the failed motor with a new motor; or (3) invest in a premium efficiency product. Here are the advantages and disadvantages of each approach and the precautions that must be taken to assure the best investment.
Mechanically generated sparks, electrostatic discharge and high surface temperatures are all potential ignition sources in explosive atmospheres. Flexible couplings play a significant role in creating and/or eliminating these explosion hazards. Consequently, the European ATEX directive applies to couplings, and for good reason.
Because operational costs ride on efficiency determinations, accurate measurements of losses occurring within the motor are paramount. The reliability of efficiency data is key to any energy-savings plan, and knowing the meaning behind the rating can make or break a smart purchasing decision.
The low voltage motors market is highly consolidated, with the top five participants accounting for more than 75 percent of the market revenues as of 2009. Low voltage alternating current (AC) motors dominate the industry, generating 92.1 percent of market revenues for 2009. That number is expected to increase to 95.9 percent by 2016, with a Combined Annual Growth Rate (CAGR) of 7.6 percent between 2006 and 2016. Low voltage direct current (DC) motors, on the other hand, are expected to have a negative 3.4 percent CAGR between those years.
Due to the delicate nature of the cranberry, pump failure is not an option.
The global economic downturn has resulted in an unprecedented attempt by world governments to help stimulate their individual economies, with the hope that these combined efforts will have a cumulative effect of breaking the downward spiral and lifting the global economy out of its crisis.
In the past year, the rate of acceleration in the cost of raw materials (including steel, iron ore, copper and aluminum) has reached unprecedented levels in the pump and rotating equipment industries.
It is impossible to balance line-to-line voltages perfectly in a three-phase circuit. In fact, line voltages typically differ by a few volts or more, but a difference that exceeds 1 percent can lead to serious trouble on the plant floor. To maintain peak energy efficiency and thwart premature failure of three-phase motors, install adequate protective devices and periodically check for voltage unbalance at the motor terminals.
Latest Motors Articles
Electric motors have had a huge impact on the pump industry.
Improved motor starters help Fabri-Kal achieve its green vision.
In the past year, the rate of acceleration in the cost of raw materials (including steel, iron ore, copper and aluminum) has reached unprecedented levels in the pump and rotating equipment industries.
The frame sizes (physical dimensions) of AC motors have changed substantially through the years. Originally, they were considerably larger than those in use today. This increased size was the result of inefficiency and the need to dissipate heat.
It has been said that Washington, D.C., is the home of the largest invertebrate population in the U.S. This, of course, jokingly refers to the population of politicians and their lack of backbone or guts required to make difficult decisions. The same analogy could be applied to the single-phase motor, as it has only one-third the “guts” of its three-phase cousin. However, it can still perform well as long as expectations are reasonable.
As a follow up on my AC Motors series, I thought it would be a good idea to provide a short overview of work, power and torque as it applies to the AC motor.
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.
Back in the early seventies, when I was in grad school, our government pledged to convert the U.S. measurement system to the metric system. A popular cartoon at the time showed a lab technician with a box of amputated human feet standing at the door of the supply room. The supply clerk was also holding a box, but his was full of volt meters. The caption was "Trading Feet for Meters." That was almost 37 years ago, and we still have most of those feet! I guess that I could say that we are still "inching" into the metric system.
Following the development of variable frequency converter drives during the 1990s, totally enclosed fan-cooled (TEFC) AC induction motors became viable options for replacing DC motors in pumping applications. The torque and speed characteristics of these motors are a close match to those required for centrifugal pumps.
Due to the delicate nature of the cranberry, pump failure is not an option.
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."
