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.
Unanticipated noise and vibration can be problematic for both occupants and processes within structures. Noise and vibration in piping systems can originate at pumps and other mechanical equipment. If the system design does not accommodate vibration, a variety of issues ranging from annoyances to actual business interruptions can occur.
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.
A flexible coupling's primary functions are connecting two shafts, transmitting power from a driver shaft to a driven shaft and accommodating the misalignment between them. With only these requirements, it would appear the coupling selection could be narrowed down to one or two types. Unfortunately, it is not that easy. All flexible couplings accomplish the above three functions, but they do so with varying degrees and attributes. It is within these secondary coupling attributes that the best coupling selection is separated from the fair, poor or even disastrous ones. No single type of coupling will be perfect for all applications.
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.
The SI system is the modern day version of the metric system, and the U.S. gets a lot of grief for not embracing its inherent transportability across international boundaries. It is the standard in our scientific community and its use is increasing in our engineering and industrial sectors, but it is still pretty unpopular with the proletariat. Why? Because the units of measure are totally unusable by most of us.
A large wastewater processing plant experienced continual problems with its influent raw wastewater pumps for several years. These pumps are rated at 70,000-gpm, 24-ft head and driven by 500-hp, 4000-V, 225-rpm Westinghouse brushless synchronous motors, 57.5-amps steady state rated current.
Most of the electric motor information we use on a daily basis is pretty straightforward.
Latest Motors Articles
Electric motors have had a huge impact on the pump industry.
Improved motor starters help Fabri-Kal achieve its green vision.
Bigger Is Better-Or At Least It Used To Be
Owing partly to tradition, the shafts of electric motors are often larger than those of the equipment they drive. Engineers were very conservative a century ago when electric motors first came into widespread industrial use, so they typically designed in a sizable margin of error. Today's engineers haven't changed much in this respect. For example, standard NEMA frame dimensions, which have been revised only once since 1950, still specify much larger shaft sizes than commonly accepted principles of mechanical engineering would require.
A large wastewater processing plant experienced continual problems with its influent raw wastewater pumps for several years. These pumps are rated at 70,000-gpm, 24-ft head and driven by 500-hp, 4000-V, 225-rpm Westinghouse brushless synchronous motors, 57.5-amps steady state rated current.
Last month we took a close look at the flow of voltage and current in purely resistive and inductive circuits. We showed how inductive reactance can inhibit the flow of primary current in a circuit and how this lagging effect determines the value of power factor (PF).
Unanticipated noise and vibration can be problematic for both occupants and processes within structures. Noise and vibration in piping systems can originate at pumps and other mechanical equipment. If the system design does not accommodate vibration, a variety of issues ranging from annoyances to actual business interruptions can occur.
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.
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.
Most of the electric motor information we use on a daily basis is pretty straightforward.
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."
