Xcel Energy Webinar
October 24, 2013
11:30 am to 1:00 pm CT
VFDs Drive Efficiency:
Learn how Variable Frequency Drives
can benefit your facility.
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Cost of doing business
Electricity costs typically account for approximately
95% of the cost to own and operate electric motors
over a ten-year operating period. The purchase price
plus installation, maintenance and other costs
account for 5% over the same ten year operating
period.*
* (Source: Center for Energy Efficiency / Motors Decisions Matter)
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Fundamentals of VFDs
Motors in the United States operate at a fixed
frequency of 60 Hz (1 cycle every 1/60 seconds).
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Fundamentals of VFDs
► A VFD changes the frequency of the current going
to the motor
► A reduction in frequency results in the shaft of
the motor spinning at speeds lower than the
standard 1200, 1800, and 3600 RPMs (depending
on the motor)
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Benefits of VFDs
► Added Control – smoother acceleration &
deceleration, automated response to system
conditions (e.g. pressure, flow, etc…)
► Power Factor Correction
► Soft Start – reduction of high starting torque and
current surges that can be up to eight times the
full-load current
► Energy Savings – especially on variable-torque
centrifugal fan and pump applications
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Energy savings potential
►Fans & Pumps offer the highest potential for
savings
►Example:
►Flow Increase 10%
►Power increase 33%
Small decrease in flow =
Bigger decrease in power
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Energy savings potential
► Savings vary by application
► Applications such as extruders and conveyors may
experience savings, but not to the same degree as
fans and pumps.
► Right tool for the right job
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Market segments
► Industrial Processes – such as glass
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manufacturing, mining, refining
Food processing
Grocery Stores
Commercial Space (retail & real estate)
Schools & Universities
Cold Storage
Hospitals
City waste water treatment plants, etc
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Common applications
► HVAC fans & pumps
► Refrigeration Compressors
► Air Compressors
► Conveyors
► Extruders
…. Just about anything that utilizes an AC motor.
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Quick review
► VFDs offer operational and power consumption
benefits
► Can be applied to a wide variety of end-uses
► Savings vary by end-use
► Pumps & fans greatest opportunities
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Example - The cost of a VFD
For K-12 school purchasing a 15 HP VFD on Fan.
15 HP VFD on a fan operating a 15 HP motor:
►Cost for VFD - $2,443
►Total labor costs - $1,910
These costs include also include:
 Engineering - $300
 VAC Tech - $255
 Electrician - $255
►Total projects costs for VFD - $4,353
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The cost of a VFD
For this K-12 school
► 15 HP VFD rebate - $1,250
► 60% of project cost - $2,612
► Energy Saved - 9,920 kWh and estimated
$575.00/year savings
► Project payback – 3.4 years
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Case study:
Greater Twin Cities United Way
VFD Upgrades yield Big return on a small investment
The situation
► A resourceful non-profit with a 68,000 sq ft facility in the
heart of downtown Minneapolis was looking for ways to
maximize their operating budget
► In need of energy efficiency upgrades so they started
with the low-hanging fruit type projects such as lighting.
But did not stop there as they wanted to maximize the
energy savings potential
► Much of the HVAC equipment had been installed in the
1960’s and air handling units did not have VFDs
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Case study:
Greater Twin Cities United Way
The Impact of installing two 15 hp VFDs
► 32,665 kWh in total energy savings
► $2,500 in rebates from Xcel Energy
► Less than 17 month payback
► Projected savings from the VFDs is $3,200 annually
► More control over their system
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Case study: City of Richfield
VFD project—turning Water Into Savings
The situation
► The water treatment plant relies heavily on constant speed
motors and VFDs to maintain a steady pump “flow” as the
water is transported out of the wells and to approximately
34,000 residents.
► Seven wells and multiple pumps
► 25 to 30-year-old motors and VFDs
► High energy costs
► The City didn’t want a hodge-podge system with dissimilar
equipment. They wanted the pumps to run and operate as
seamlessly as possible.
► Running similar equipment helped synchronize operations
and improve efficiency.
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Case study: City of Richfield
VFD project—turning Water Into Savings
Results of the City’s Efforts
► 375,570 kWh in total energy savings
► $20,865 in rebates from Xcel Energy
Additional Impacts
► Lower energy costs on each statement
► Increased reliability in motors & VFDs
► Ease of use with automated system
► Improved energy efficiency
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Quick review
► VFDs have energy savings benefits
► To see more customer case studies visit
Responsible By Nature.com
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When VFDs are not beneficial
►Constant speed or power (hp): when a motor is set
to run at full speed
►High static pressure installations: Drives on
submersible pumps or any above ground pumps
that operate systems with a high static dominated
pressure level
►Poor Sequencing: The best sequencing for VFD
systems depends on the end use application
(Source: Esource.com)
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What’s most important to
Facility Managers & Engineers
► Keep plant running – increase uptime
► Reduce plant operating costs
► Often heard –
“Keep the facility running but don’t spend a nickel
more than you need to…..”
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Motor Decisions Matter (MDM)
Change the Purchasing Pattern
► Commitment
► Set goals
► Make action plan
► Implement plan
► Verification
► Recognize achievements
► Repeat cycle
ENERGY STAR ®. 10-10-2013. US Environmental Protection Agency and US
Department of Energy. http://www.energystar.gov
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More resources
Motor Decisions Matter (MDM)
► Facility managers are increasingly under pressure
to reduce energy costs, increase productivity and
reduce greenhouse gas emissions. Sound VFD
management is a key strategy to achieve these
goals.
► Start today. Because managing a plan is easier
than managing a crisis.
► Web address: motorsmatter.org
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More resources
The Energy-At-Risk Financial Analysis Tool
can help you…
► Determine the payback and cost of your VFD &
other energy efficiency upgrades.
►Simple payback periods
►ROI
►Break-even analysis
►The cost of doing nothing
► Visit XcelEnergy.com to access this free tool
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Rebates
►To offset the costs of VFDs Xcel Energy offers
rebates ranging from $400 to $8,000
►On either a fan or a pump
►From 1 to 200 hp
►Custom rebates are also available for VFDs
►Chillers, air compressors, refrigeration
compressors, etc
►Over 200 hp
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Quick review
► Xcel Energy offers rebates to off-set equipment
costs
► We have tools to help you determine the cost of a
VFD
► VFDs are beneficial in many market segments and
many types of applications
► But are especially beneficial on fans and pumps
► Sometimes VFDs are not beneficial
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Contact us
► Let us help you determine if VFDs can benefit your
facility.
► Contact your account manager or the Energy
Efficiency Specialists at 1-800-481-4700
► Or email us at energyefficiency@xcelenergy.com
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Thank you.
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