DUKE ENERGY'S INVESTMENT IN PREDICTIVE MAINTENANCE PAYS DIVIDENDS
CHARLOTTE, NC -- (December 9, 1997) -- The stakes are always high for Duke Engineering & Services (DE&S), an affiliate of Duke Energy Corporation. One of the nation's largest energy providers, Duke Energy Corporation controls more than 12 percent of the natural gas transport system from Texas north to the Canadian provinces and provides electricity to approximately two million customers in the Carolinas.
"Back in the early 1980s, power plants across the country were exhibiting catastrophic failures," said Frank Hale, engineer. "Even with preventive maintenance, everyone was so busy fighting fires that there was never time for root cause analysis. That wasn't good enough for us at Duke."
Supported by Duke's commitment to cutting-edge technology, Hale and fellow engineer Michael Kelly helped initiate the company's predictive maintenance efforts in 1983. The program now includes vibration analysis, the most mature technology; as well as rotor-dynamic analysis, thermography, lubrication analysis, laser shaft alignment, electric motor testing, balancing, thermal growth monitoring and failure analysis for root-cause evaluations.
What distinguishes Duke's predictive maintenance function is an emphasis upon the following critical factors:
Predictive Maintenance And Analysis Team The hub of DE&S' predictive maintenance program is a bustling, crowded group of offices in Charlotte, NC, home of the Predictive Maintenance and Analysis Team (PMAT). There's no place for hierarchy within this eclectic team that represents a full range of skills and technologies. It's a "roll up your sleeves" combination of engineers, technicians and support staff, all focused on the goal of bringing added value through a total predictive maintenance package, both for internal and external customers. "People are surprised that we provide a full range of services to external clients as well as internal clients," said David Moss, the PMAT supervisor. "The expertise that Duke has developed to support our plants also allows our external clients to operate more efficiently and profitably."
Among the internal customers are Duke's nuclear power stations, typically the most advanced in the use of predictive technologies. Although the nuclear stations perform a variety of maintenance functions themselves -- including vibration, thermography and oil analysis -- electrical maintenance has generally been performed externally. That's where the Predictive Maintenance Analysis Team was able to expand its level of service.
Motor Circuit Analysis at Duke
"The failure rate of large motors and the use of
outdated technologies that were potentially destructive to the
motors were concerns throughout the organization," said
Ricky Waters, PMAT technician. "Customers were performing
their own vibration and oil analysis, but the organization was
lacking the ability to track and trend electrical
performance."
The answer for PMAT was motor circuit analysis, using the MCE™ Tester from PdMA Corporation. A typical scenario took place in the Spring of 1997 in a four-year-old power plant. Preliminary baseline data had been taken in March 1996, and PMAT members returned in March 1997 to retest the motors.
After noting high phase-to-phase resistance from the motor control center on three coal pulverizers, Waters and fellow PMAT technician Albert Kluttz recommended to the plant engineer that the feeder cables be disconnected at the motor, isolating it from the circuit to test the motor alone. Upon disconnecting the cables, Waters noticed suspect areas and dissimilar metal connections (carbon steel bolts and copper connections) as well as signs of corrosion, so he knew he had identified the source of the high resistance.
Waters and Kluttz cleaned the connections, reconnected them and retested -- all three motors in one day. The client was extremely pleased with the results. Not only had PMAT diagnosed the problem and recommended a solution -- but they were also able to make the necessary repairs on the spot, avoiding the need to contract for additional technicians to make repairs at the 70-megawatt station. "That's the value-added component of our service that differentiates us from other vendors," noted Waters.
An even more dramatic example took place recently when a reactor coolant pump motor tripped during the night at one of Duke's nuclear power plants. Electricians called Waters in the middle of the night, after they had "meggered" the motor. They told Waters they thought it was grounded but wanted him to come immediately to test with the MCE Tester. When he did, he detected a shorted winding, providing the needed condition verification of this crucial piece of equipment.
"You go when they call because they are your customer," says Waters. "With the MCE, you don't just collect data, you can troubleshoot and then repair, if necessary. We take ownership of the machines we maintain." Waters added that the potential for lost generation was not the only concern in keeping the motors running properly. The efficient operation of reactor coolant pumps is of great importance to organizations such as the U.S. Nuclear Regulatory Commission and Institute for Nuclear Power Operations, who want assurance that the machines are functioning and therefore capable of cooling the reactor properly.
MCE Tester
PdMA's MCE Tester, designed for effective condition monitoring
and new motor quality assurance, is used for Quality Assurance,
Trending and Diagnostics/Trouble Shooting. The comprehensive MCE
tests all potential fault zones: stator, rotor, insulation,
airgap and power circuit.
A versatile tool, MCE tests AC induction, synchronous, wound rotor, DC and specialty motors such as servo and spindle; correlating with most predictive technologies to refine or confirm troubleshooting efforts.
Proprietary MCE software provides a precise and objective method of reviewing, tracking, trending and comparing data, as well as generating immediate reports. MCE tests at the motor control center, local disconnect or directly at the motor, and tests are nondestructive to the motor and circuits. For ease in the field, the MCE is portable, lightweight and battery-powered.
Conclusion
"We're the new technology conduit for the company,"
adds Waters. "We're now introducing motor circuit analysis
through the MCE Tester to the nuclear stations, and predict that
they'll incorporate it into their own operations."
As an affiliate of Duke Energy Corporation, Duke Engineering & Services provides a variety of maintenance-related services to clients throughout the nation and brings a unique owner/operator perspective to project planning and execution. DE&S has worked with utility, industrial, commercial and government clients to maximize efficiency, enhance plant availability and reduce costs. Headquartered in Charlotte, NC, DE&S has an extensive domestic and global presence, with 26 U.S. business offices, 12 international offices and projects underway in more than 50 countries. For more information concerning DE&S, please contact David Moss at (704) 382-4458 or e-mail at Dtmoss@duke-energy.com
PdMA Corporation, committed to providing customers with professional and technically advanced condition assessment equipment and services, provides advanced motor circuit evaluation technology, full lubricant analysis, maintenance program analysis, PdM training and on-site services. PdMA Corp., 5909C Hampton Oaks Parkway, Tampa, FL 33610; (800) 476-6463; fax (813) 620-0206.
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