MOTOR CIRCUIT ANALYZER PLAYS PIVOTAL
ROLE IN DUPONT/CONOCO PILOT MAINTENANCE PROGRAM
PONCA CITY, OKLA. -- (September 26, 1996) -- A revolutionary electric motor circuit analyzer is playing a central role in a pilot maintenance excellence program now in its third year at Conoco, Inc.'s Ponca City Refinery.
Electrical reliability technicians are using the PdMA Corporation's self-contained, portable Motor Circuit Evaluator (MCE™) System 3000 to troubleshoot and conduct predictive maintenance on the refinery's 1,870 electric motors, which range in size from 8,000 horsepower to fractional.
"The MCE tester is another tool for the toolbox. It's a great little instrument, especially when combined with infrared and vibration technology," said plant Electrical Engineer Curtis Dick.
The MCE Tester "The MCE's found things the surge tester hasn't found," Dick said. The tester can help detect rotor anomalies, including broken bars or end rings, warped or bowed shafts, eccentricity and porosity, and stator defects, including turn-to-turn faults, phase-to-phase leakage, improper winding and core grinding or damage. In addition, the tester can be used to assess the condition of the windings and the insulation system.
The MCE tester being used by Conoco is equipped with PdMA Corp.'s new WinVis™ software. WinVis' user-friendly, Windows interface and complete "Help" system permit quick database set-up based on the plant layout; fast entry or duplication of nameplate data; testing and assessment of a variety of motors in the field; the generation of graphs, charts and reports; and exporting data to other applications.
The MCE's testing capabilities have been expanded to include polarization index, dielectric absorption ratio and commutator bar-to-bar testing.
"We're finding out that we have a heck of a lot of good motors out there," Dick said of the ac induction and synchronous motors at the 150,000 barrel per day refinery. The tester can also be used on dc motors and wound rotor motors.
Maintenance Excellence At Conoco The initial goal of Conoco's maintenance excellence program was to test all 1,870 motors at the refinery on an annual basis. However, when a random sample of 300 motors showed that they were all good, the program focused on motors greater than 460 volts as well as critical motors. Motors were deemed in critical need of testing if their loss meant that a refinery unit went off-line, if they had an unreliable spare, or if their spare was underrated.
The program now tests approximately 500 refinery motors
annually, including quality checks of new motors, those returned
from the repair shop, and motors with high 2x vibration.
Individual refinery units produce gasoline, jet fuel, diesel fuel
and coke. Failure of the refinery's Fluidized Catalytic Cracking
Unit's wet gas compressor motor could cost Conoco over $300,000
per day in lost gasoline production.
"A classic example of how we're using the system is in the case of pump failures. In the past, we'd pull the motor along with the pump. The motor would be cleaned and the bearings replaced," said Electrical Reliability Technician Michael Mead. "Now, with the MCE and vibration system, we are able to determine the motor's condition in the field and avoid the cost of pulling the motor."
The Next Step The lightweight MCE tester can also be used as a quality assurance tool or as a tracking and trending device for ac induction motors. Plant engineer Dick noted that the refinery recently started trending each motor critical to the production process in an attempt to identify potential problems and plan convenient windows to work on those deemed in need of repairs.
"We really didn't have an extensive preventive maintenance program for our motors in the past. It was really a hit-or-miss proposition," Dick said. "Once the trending program becomes firmly established, we're confident that we'll be able to demonstrate that substantial savings have been realized by the company. Now the other refineries are getting pretty interested in what we're doing here."
Dick added that the Dupont/Conoco Corporate Motor Technology Team is now considering endorsing the MCE tester for use at all company facilities. Conoco, Inc., headquartered in Houston, is a subsidiary of the DuPont Company of Wilmington, Delaware.
The PdMA Corporation, based in Tampa, is a predictive maintenance company which also offers advanced motor circuit evaluation, full lubricant analysis, maintenance program analysis, and predictive maintenance training.
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