Variable Speed Drive Centrifugal Chillers

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Variable Speed Drive Centrifugal Chillers
Chiller System Optimization and Energy
Efficiency Workshop September 16,17,18, 2003
York International Corporation 320 Norwood Park
South Norwood, MA 02062
David Klee, Senior Sales Engineer
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Todays Topics

• Theory of Operation
• Harmonics
• Secondary Benefits
• Questions

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Car Analogy
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Prerotation vanes
Electric motor
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Constant Speed

• Accelerator pegged to the floor

• Brake to slow down

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Variable Speed

• Full control of accelerator
• Brake only if necessary

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How it Works
Chilled Water Temp. Temp. Setpoint Evap / Cond
Pressure PRV Position Actual Motor Speed
Optimum Motor Speed
Optimum PRV Position
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Weather Data
98.3
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Head Pressure
Lowering condenser water temperature Lowers
head pressure Reduces compressor work Reduce
s energy consumption
Pressure
Condenser
Head Pressure
Compressor
Evaporator
Enthalpy
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Variable Speed Centrifugal Chillers
30 Energy Savings
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Harmonics

• What do they do?
• Cause distortion of the voltage and current sine
  wave
• Increase the current used by a product
• Increase the heating of utility wires and
  transformers
• Disrupt the operation of other equipment

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Harmonics

• Many utilities are pushing for lower harmonics
• The current standard is IEEE 519-1992
• It developed acceptable levels of voltage and
  current distortion produced by a product
• This is a guideline not a required law

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Harmonics Filtration

• Specially designed filter to keep a building in
  compliance with IEEE-519
• Filter is unit mounted in the same cabinet as the
  VSD
• Still has the UL label
• Filter parameters displayed on the chiller panel

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Current Generation VSDs

• Unit Mounted
• UL Approved
• Cooling Circuit
• Any Refrigerant
• 3rd party or 1st party

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Standard Features

• Circuit breaker with 65kA withstand
• UL listed ground fault protection
• All drive displays on chiller panel
• Single point wiring
• No additional floor space required
• Harmonics Attenuation Packages

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Operating Benefits

• Slower minimum speed of 30 hz
• 0.95 or better total power factor at all loads
• 0.98 or better total power factor with filter
• Takes the place of the starter
• Reduces inrush to less than 100 FLA
• Anti-recycle timer - 0 min
• Reduced driveline wear

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Sound

• Generated by refrigerant discharge at high
  velocities

• Slowing compressor reduces sound

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Inrush Current
500
400
300
Motor FLA ()
Star Delta Starter
200
100
Millennium VSD
0
5
10
20
40
Time (sec)
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Soft Start

• Never exceed 100 FLA
• Increase motor life
• Excellent for limited inrush capabilities
  (generator starts)

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Local Installations

• Mass General Hospital
• Harvard University
• Boston City Hall
• Northeastern University
• BAE Systems
• Prudential Center
• 111 Huntington
• Gillette Company
• Raytheon Company
• Museum of Science
• Royal Sonesta Hotel

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Questions?
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YORK OptiSpeedTM Variable Speed Drive
Designed for Optimum Real-World Energy
Performance