Pumps & Systems, September 2007A large wastewater processing plant experienced continual problems with its influent raw wastewater pumps for several years. These pumps are rated at 70,000-gpm,...
Pumps & Systems, October 2007With highly reliable electrical systems, protective relays may be called upon to operate very infrequently. However, the effects of faults and abnormal conditions can...
InnovationIntroduced 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...
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...
With highly reliable electrical systems, protective relays may be called upon to operate very infrequently. However, the effects of faults and abnormal conditions can be severe and protective relay...
Pumps & Systems, June 2007When 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...
An argument in favor of IEEE-841's provision for motor bearing protection.In June, 2007, a reader asked Electrical Apparatus magazine, "How long should motor bearings last?" The answer will astound...
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...
Due to the expense and labor required, most facilities need to maximize the life of their motors. Electrical, insulation resistance and thermal measurement are three tests that can troubleshoot...
Pumps and Systems, June 2009Editor's Note: Click here to see a sample alignment data formProper alignment of the pump shaft with the driver can reduce vibration and significantly improve reliability....
Pumps & Systems, November 2008Mechanical 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...
Couplings are often forgotten until a project is nearing its end. With time running out, users often purchase whatever a supplier has in stock instead of the best solution for the system....
Pumps & Systems, June 2008Following the development of variable frequency converter drives during the 1990s, totally enclosed fan-cooled (TEFC) AC induction motors became viable options for...
Pumps and Systems, February 2007All electric motors (motors) have a housing that contains the working components of the motor. In the U.S., the enclosure describes this housing. The enclosure should...
AC Motors: Magnetism and the DC Motor
I received many comments on my four-part series on AC Power, and most of them were very positive. Several readers, however, thought they were too elementary. Ireminded them that the title of my column...
Pumps & Systems, June 2007In many pump installations, problems such as jams and suction loss can lead to serious damage to the motor or pump long before the thermal overloads trip. These problems...
Electric Motors: Driving to Higher Efficiency
The freefall in electric motor sales is a direct effect of the worldwide economic downturn, which has severely depressed industrial and commercial productions. Despite the 20 to 30 percent drop in...
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,...
Pumps and Systems, June 2009The 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...
AC Power (Part Four): Transformers
Last of four partsLast 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...
AC Power Part 1: AC Versus DC
First of Three PartsThis three part primer is a basic introduction to AC power for those in the pump industry who need a place to start. It will also provide several web references to access if you...
Electric Motor Efficiency Regulations Part Two
What pump manufacturers and pump users need to know about small electric motor regulations. Second of Two Parts.Part One of this two-part article discussed Integral HP AC Motors from 1 to 500 hp...
Coupling Considerations for Pump Applications
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...
AC Power Part Two: Voltage Versus Frequency and the Three Phase Curve
Last month, we ended with a discussion of the relationship between peak and RMS (or effective) voltage. We found that the RMS voltage will always be 0.707 that of peak voltage, and peak voltage will...
Intelligent Pump Cleaning Cuts Maintenance Time
The installation of an AC drive with an advanced software tool has dramatically cut call-outs for blockages at an Irish county council pumping station. Pump control software has been installed to...
AC Power (Part Three): AC Circuit Loads
AC Circuit LoadsLast month we discussed the relationship between voltage and frequency and tried to make that somewhat complex three phase sine wave a bit more understandable. This month we will...
Trends in Variable Speed Technology
Choose the right variable speed motor for specific equipment.Why and how do leading OEMs choose a variable speed motor for their equipment? While rated efficiency has been an important driver in the...
Pump Protection
When can you trust your overload relay to keep you safe?The oil and gas industry depends heavily on pumps, and their reliability is vital for safety and economic reasons. For many years, the...
Predictable Pump Motor Maintenance at a Cranberry Bog
Due to the delicate nature of the cranberry, pump failure is not an option.When a pump or motor fails at Sea Wind Cranberry Farm in Langlois, Ore., farm manager Knute Andersson's business is at stake....
Safer and Smarter Single Phase Pumps
New motor starting controller provides one solution.Pump systems come in all sizes, from large municipal plants to small residential systems using single phase pumps that are three hp or smaller. All...