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Big Picture Perspectives: Industrial Motor Systems
Industrial motor systems:
- are the single largest electrical end use category in the American economy
- account for 25% of U.S. electrical sales
Motor loads dominate industrial electrical energy consumption
ProcessHeating
Electrolytics
Motor-DrivenEquipment
Lighting& Other
Over 60% of industrial motor-system energy consumption involves fluid handling
Pumps24.8%
Fans13.7%
Compressed Air15.8%Refri
geratio
n
6.7%
Material handling
12.2%
Material processing22.5%
Other
4.3%
Just over 1/3 of themotor population
accounts for almost2/3 of the energy
A large portion arecentrifugal devices
A small fraction of the motor population is responsible for most of the energy consumption
0102030405060708090
100
> 10
00
> 50
0
> 20
0
> 10
0>
50>
20 > 5
> 1
Cumulative motor horsepower range
Pe
rce
nt o
f en
erg
y/po
pul
atio
n
Population
Energy10% population
uses 80% energy
Note the descending order (left to right)
Comparing life cycle costs: automobile and pump/motor combination
Common assumptionsDiscount rate = 8%Non-energy inflation rate = 4%Lifetime = 10 years
Item Automobile Pump & motorInitial energy cost rate $1.50/gal 5 cents/kWhrEnergy inflation rate 10%/yr 5%/yrOperating extent 12,500 miles/yr 7000 hr/yr (80%)
Life cycle cost - example automobileFull size vehicle, $28,000 price tag, 24 mpg
Purchase:51%
Maintenance, Insurance
31%
Energy16%
Miscellaneous2%
First year energy cost = $69,000First year energy cost = $69,000
Life cycle cost - 250-hp pump and motor$28,000 initial cost, 95% motor efficiency
First year energy cost = $69,000
Purchase3%
Maintenance, downtime
21%
Energy74%
Miscellaneous operations
2%
First year energy cost = $19,600First year energy cost = $19,600First year energy cost = $19,600
Higher first cost pump and motor ($56K),low service time (2,000 hrs/year)
Purchase20%
Maintenance
15%
Energy59%
Miscellaneous operations
6%
Pump and motor component efficiencies:Seventy+ years of progress
Pump MotorYear efficiency (%) efficiency(%)
1928 80 87.5
1955 85 90.5
2002 88 95.4
Achievable efficiency estimates for commercially available 75-hp pump and motor
The Pareto Principle or "the vital few and trivial many"
J. M. Juran, who first used the term "Pareto Principle" also coined a more descriptive phrase:
Input
20%80%
Output
20%80%
(Relatively few are responsible for relatively much)
"The VITAL FEW and the trivial many"
Prescreening to narrow the field of focus - i.e., to select the VITAL FEW for further review
All plantmotor systems
Policies andpractices bin
Filter 1
Seldom used,small loads
Big loadsthat run a lot
Filter 2
Big centrifugalloads that run a lot
Symptom orexperienced-based
segregationLarge non-centrifugal loads
* *
Moderatepriority
* Productivity/reliability-critical systems sent to higher priority levels
HighestPriority
• Look for:
– Throttle valve-controlled systems
– Bypass (recirculation) line normally open
– Multiple parallel pump system with same number of pumps always operating
– Constant pump operation in a batch environment or frequent cycle batch operation in a continuous process
– Cavitation noise (at pump or elsewhere in the system)
– High system maintenance
– Systems that have undergone change in function
Example symptoms in pumping systems that indicate potential opportunity
Many life cycle elements influence reliability, cost, and productivity of motor-driven systems
– Design– Procurement– Construction/Installation– Testing/Troubleshooting– Operation– Maintenance– Insurance– Regulations– Decommissioning– Down time– etc…..
Most of these elements are interdependent
AffectMaintenance
Design
ProcurementConstruction/InstallationTesting/Troubleshooting
OperationMaintenance
InsuranceRegulations
Decommissioning
Example: other factors do or may affect maintenance
Down time
Just like any stable control system, optimal asset management requires feedback
Maintenancedoes, shouldor may affect
Design
ProcurementConstruction/InstallationTesting/Troubleshooting
OperationMaintenance
InsuranceRegulations
Decommissioning
Unfortunately, feedback is often weak or non-existent
Down time
Life cycle elements are an integrated system, much like the physical systems themselves
• The elements can be treated as components
– For example, procurement can be on lowest first cost basis, without regard to the effect on maintenance or operations
• The elements can be treated as a system
– For example, procurement considers all the elements of cost and is based on lowest total life cycle cost
Ideally, all the life cycle elements could be analyzed with a single common denominator
– Design– Procurement– Construction/Installation– Testing/Troubleshooting– Operation– Maintenance– Insurance– Regulations– Decommissioning– Down time– etc….
Cost
When considering options, some elements can often be disregarded - even at the system level
• Insurance
• Regulations
• Decommissioning
Alternatives & supplements to life cycle cost analysis
• Probabilistic analysis of reliability & risk (commercial software is available)
• Engineering judgment
• Weighted/graded evaluation
• Sole-source contracting (initial selection would involve overall cost/reliability considerations)
• Outsourcing - shed some of the decision-making responsibility
Contingency planning - making the change when a failure occurs
• The alternatives evaluation picture changes dramatically when failures occur
• Changes that couldn't be justified when the system was functional may very well be after failure
• The alternative may actually be less costly than simple repair/replace of the existing component