By Mike Howell
EASA Technical Support Specialist
For many industrial plants, maintenance strategies and decisions relating to the electric motors in use are among their most critical. Without question, motors are the primary workhorses for many of these plants—driving machinery, pumps, conveyors, and other vital equipment. So when they don’t work properly or fail, the impact on regular plant operations can be enormous.
When faced with an ailing or failed motor, plant operators typically consider whether to repair or replace it. According to a 2014 study conducted by Plant Engineering magazine for the Electrical Apparatus and Service Association (EASA), just more than one-half of plants have a policy of automatically replacing failed electric motors below a certain horsepower rating. While that horsepower rating varied depending upon the plant’s installed motor population, the average rating was 30 hp.
While such policies address a portion of the motors used at most plants, they do not cover what occurs with those motors. That question was addressed in a more recent research project commissioned by EASA that focused on the disposition of electric motors considered for repair. The research showed that just over three-quarters (79%) were repairable, with the remainder (21%) replaced. Within the repaired electric motor group, mechanical repairs were the most common (49%), compared with electrical rewinds (30%). Further, over the past three years, mechanical repairs are trending higher, while the electrical rewinds are declining.
The article looks at some of the reasons for these motor repair trends:
- Availability of a suitable replacement
- Cost of repair vs. replacement
- Repair provides opportunity to determine (and address) root cause
- Regular preventive and predictive maintenance practices can provide “early warning”
- ANSI/EASA standard establishes motor repair best practices
- EASA accreditation provides third-party assurance of motor repair practices
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ANSI/EASA AR100
More information on this topic can be found in ANSI/EASA AR100
EASA Technical Manual
More information on this topic can be found in EASA's Technical Manual- Section 2: AC Machines
- Section 3: DC Machines
- Section 7: Electrical Testing
Related Reference and Training Materials
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