This presentation presents the Maintenance of electrical machines. Need of Maintenance, types of maintenance

1. Maintenance of Electrical Machines
By
Ankit Singh Basera
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3. Introduction
• The dictionary defines maintenance as follows: “the work of keeping
something in proper condition; upkeep.”
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4. Bath Tub Curve
Time/ operated life
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5. The initial infant mortality period of bathtub curve is characterized by high failure rate
followed by a period of decreasing failure. Many of the failures associated with this region
are linked to poor design, poor installation, or misapplication.
The infant mortality period is followed by a nearly constant failure rate period known as
useful life
The wear-out period is characterized by a rapid increasing failure rate with time. In most
cases this period encompasses the normal distribution of design life failures.
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6. Necessity of Maintenance
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7. Maintenance
Reactive
Maintenance
Preventive
Maintenance
Predictive
Maintenance
Reliability
Centered
Maintenance
Types of Maintenance
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8. 1. Reactive Maintenance
• Reactive maintenance is basically the “run it till it
breaks” maintenance mode.
• Degraded equipment is only repaired or replaced
when the effect of degradation on process
output becomes unacceptable.
• Small organizations which lack dedicated
maintenance staffs often utilize this approach by
default, and larger and more sophisticated
organizations in the manufacturing sector also
frequently apply it to noncritical equipment
Advantages:
1. Low cost.
2. Less staff.
Disadvantages:
1. Increased cost due to unplanned
downtime of equipment.
2. Increased labour cost, especially if
overtime is needed.
3. Cost involved with repair or
replacement of equipment.
4. Possible secondary equipment or
process damage from equipment
failure.
5. Inefficient use of staff resources.
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9. 2. Preventive Maintenance
• It is also called Time-Based Maintenance (TBM)
or Scheduled Preventive Maintenance.
• Actions performed on a time or machine-run-
based schedule that detect or mitigate
degradation of a component or system.
• Maintenance activities are performed at fixed
intervals of calendar time, operating hours, or
operating cycles.
• It comes in two forms:
1. inspection and observation
2. intervention and replacement
• It is the predominant approach among relatively
sophisticated operators of plants where
productivity and safety is a serious concern
Advantages:
1. Flexibility allows for the adjustment of
maintenance periodicity.
2. Increased component life cycle and energy
savings.
3. Reduced equipment or process failure.
4. Estimated 12% to 18% cost savings over
reactive maintenance program.
Disadvantages:
1. Catastrophic failures still likely to occur.
2. Labour intensive.
3. Includes performance of unneeded
maintenance.
4. Potential for incidental damage to
components in conducting unneeded
maintenance.
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10. 3. Predictive Maintenance
• It is also called Condition-Based Maintenance
(CBM).
• It involves monitoring for evidence of changed
conditions within the equipment. The amount of
change and the rate of change are tracked and
used to predict the time of failure.
• It uses planned maintenance tasks that are based
on equipment’s previous operating history, and
trending of the maintenance data.
• Basically, predictive maintenance differs from
preventive maintenance by basing maintenance
need on the actual condition of the machine
rather than on some pre-set schedule.
Advantages
1. Increased component operational
life/availability.
2. Allows for pre-emptive corrective actions.
3. Decrease in equipment or process
downtime.
4. Decrease in costs for parts and labour.
5. Improved worker and environmental
safety.
6. Improved worker morale.
7. Estimated 8% to 12% cost savings over
preventive maintenance program.
Disadvantages
1. Increased investment in diagnostic
equipment.
2. Increased investment in staff training.
3. Savings potential not readily seen by
management.
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11. 4. Reliability Centred Maintenance
• It is also called Condition-Based Maintenance
(CBM).
• “a process used to determine the maintenance
requirements of any physical asset in its
operating context”.
• It approaches the structuring of a maintenance
program recognizing, which equipment will have
a higher probability to undergo failures and
accordingly need to be prioritized and optimized.
• Basically, predictive maintenance differs from
preventive maintenance by basing maintenance
need on the actual condition of the machine
rather than on some pre-set schedule.
Advantages:
1. Can be the most efficient maintenance
program.
2. Lower costs by eliminating unnecessary
maintenance or overhauls.
3. Minimize frequency of overhauls.
4. Reduced probability of sudden equipment
failures.
5. Able to focus maintenance activities on
critical components.
6. Increased component reliability.
7. Incorporates root cause analysis.
Disadvantages:
1. Can have significant cost of start-up,
training, equipment, etc.
2. Savings potential not readily seen by
management.
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12. Application of Different Maintenance Strategies
Reactive Maintenance Preventive Maintenance Predictive Maintenance
Small parts and equipment Equipment subject to wear Equipment not subject to wear
Non-critical equipment Consumable equipment Critical equipment
Equipment unlikely to fail
Equipment with known failure
patterns
Equipment with random
failure patterns
Redundant systems
Manufacturer
recommendations
Systems which failure may be
induced by incorrect
preventive maintenance
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