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- Cooling Tower Drives
- January, 2010
- Motorreductores y Controles SA de CV
- www.mcweb.com.mx
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- Matched Performance VS1CTD drive and RPM-AC Motor
- Baldor VS1CTD drive designed for variable speed operation
- High Torque Direct Drive Motor:
- Laminated Frame IPM (Permanent Magnet)
- Motor is designed as a drop in replacement for existing gearbox
packages; matching bolt holt patterns (may require a mounting plate)
- Water tight motor uses fan air stream for optimal cooling
- Improved efficiency over standard gearbox and motor
- Fan couples directly to the motor shaft
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- Industry requires improved motor power density and increased efficiency
- Permanent Magnet Motors meet these needs
- Due to dramatic improvements in PM materials, these types of motors are
now viable alternatives to standard induction motors
- Laminated RPM-AC frame allows more room for active material creating a
power dense package
- Frame construction improves thermal transfer and heat dissipation
capability of the motor
- Efficiency of PM motors is a band level higher than induction cast iron
frame motors
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- Laminated Frame Interior Permanent Magnet rotor technology
- Motor is compact enough to direct drive cooling tower fans
- Finned Laminated frame in fan air stream is optimum construction for
application
- VPI electrical insulation system for extreme environmental conditions
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- Sealed insulation system:
- Same insulation system used in off shore oil drilling motor
applications
- Provides ultra reliable motor life in hostile north sea environment
- Drive end sealing utilizes a slinger and an Inpro seal for superior
bearing protection.
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- Designed for the cooling tower industry
- Focus is on ease of startup, minimal maintenance and efficiency of
operation
- Matched Performance drive and motor
- RPM-AC motor models are stored
in the VS1CTD drive software
- Precise control capability
- Simplified Cooling Tower Startups
- Eliminates the need for users to input data
- Basic software parameter set designed exclusively for the cooling tower
industry
- Designed around proven H2-Technology
- Unique Sensorless Vector Software
- Smooth, low speed operation
- Optimized motor control increases efficiency
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- Optimized motor speed
- Traditional cooling towers are designed for the “Worst Case” (highest
air flow) scenario
- Running the fan at reduced speed saves energy and cost of operating the
tower
- Allows for optimized cooling of return water; increasing the efficiency
of compressor operation and this components life
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- Cooling Tower Loading
- Typical cooling fans run the majority of
their time lightly loaded
- Traditional AC motor power factor is negatively impacted by light
loading
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- Trickle Current Heating is used to keep the
temperature of the motor above the dew
point during times when not in use.
- Set by a single parameter (units of amps)
- Limited to 50% FLA of motor (0 amps disables)
- Wattage calculation based upon amperage
and motor stator resistance
- Enabled automatically once motor stops and
after a 300 second delay
- Digital input provided for customers that want
control via hardware input for CTD operating modes
- Modbus coil provided for building automation
control systems
- Additional benefit of providing anti-windmilling torque
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- Communication Networks:
- System automation and control can be a requirement for cooling tower
operations
- The VS1CTD communicates with multiple networks:
- Dynamic Braking
- Input / Output Reactors
- Keypad Extension Cables
- High Resolution Analog I/O Expansion Board
- Ethernet Browser Board
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- On the campus of Clemson University in Clemson, SC
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- Cooling Tower Information
- Built in 1986
- Ceramic Cooling Tower Job # CT-1206
- 2 Fan Units
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- Existing Motor Nameplate Information
- Both Units were Reliance Motors
- Motor 1 S/O: 1MOF26353-G1-WM
- Motor 2 S/O: 1MOF26353-G2-WM
- Frame Size: 326T
- Rating: 50HP @ 1765 RPM / 12.5 HP @ 885 RPM
- 480 V / 3 Phase / 60 Hz
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- Amarillo Gear Box Information
- 2 Units
- Model: 155 (single reduction)
- Gear Ratio: 8.5 to 1
- Pinion: 8 Teeth
- Ring Gear: 68 Teeth
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- Fan Information (Both Units)
- Manufacturer: Hudson Fans
- (80% of all towers use these fans)
- Model: APT-18B-5
- Diameter: 18’ - 0”
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- New motor is 93.6% efficient (existing motor is 22 years old)
- Gearbox manufacturer states gearbox efficiency at 96%
- Test data indicates mechanical system (gearbox, couplings, driveshaft)
is 90.2%
- Data verified by Clear Air Engineering on site at Clemson University
- * Published Data
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- Laminated Frame Interior PM motor technology enables direct drive
gearless system
- Gearbox low speed lubrication
issues are eliminated
- No drive shaft
- No couplings
- No guards
- No alignment
- Minimizes blade load fluctuation
- Motor can be configured to be drop in
replacement for gearbox
- Clemson University Beta site was a drop in
- Conversion at Clemson took under six hours
- Improved Reliability and Maintainability
- Simplified System
- Increased overall system efficiency
- Elimination of gearbox provides biggest improvement in overall fan
drive system efficiency
- Direct motor reduces noise level of cooling tower
- Although a Baldor V*S drive is required, the majority of cooling towers
are being retrofitted with VFDs for overall cooling tower system
efficiency improvement
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- Simplified installation and reduced maintenance are the major selling
points
- No gear, line shaft, couplings guards, etc
- Biggest gains in energy savings when system takes advantage of airflow
- Reduces the overall Motor HP requirements for the fan
- 50-60% energy savings are typical
- Applying drives on NEMA induction motors saves a similar amount of
energy as with the Baldor PM direct drive motor solution
- Old retrofits can show significant energy savings
- Both PM or Induction motor upgrades if the original gear and motors are
lower efficiency
- 10-15% energy savings are possible
- Minimal energy savings if variable speed is not required
- Efficiency difference between Baldor IPM motor and newer efficient
installation is minimal
- 2% Plus or minus energy savings is the expectation
- The primary reason is that the efficiency of the PM motors at the very
low speeds of the fan is not very high, drive losses also have to be
considered
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- Calc Motor Model Requirements
- Enter motor design number for existing motor
- If non-existent, prompted to use custom motor block
- For new motor, enter data from motor electrical design into custom
motor parameter block
- Execute Calc Motor Model
- Drive will not run until successful
(fault occurs indicating this problem)
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- Please have data sheets filled out when sending in Quote requests
- Fan Shaft Hp required
- Presently assuming a required min air flow over motor of 500 fpm for 250
frame & 750 fpm for larger frames. This is one of the inputs
required.
- We will run an evaluation of the application.
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