VLT Drives Applications (VIDEOS)

Some of the interesting applications done with Danfoss VLT drives:

  1. VLT drives in large desalination plant
  2. VLT drives control cooling tower fans
  3. VLT control optimizes spindle speed in Indian textile factory
  4. VLT frequency converters drive bagage handling system
  5. VLT Drives Save 78% Energy in Chester Zoo

1. Details of the machine to be controlled

  1. Required plant/machine characteristics
  2. Torque characteristics, stalling torque, acceleration torque
  3. Speed control range, cooling
  4. Power consumption of the converter and the motor
  5. Operating quadrants
  6. Slip compensation (dynamic)
  7. Required ramp-up and ramp-down times
  8. Required braking times, brake operating time
  9. Direct drives, gears, transmission components, moment of mass inertia
  10. Synchronisation with other drives
  11. Operating time, controls
  12. Computer linkage, interfaces, visualisation
  13. Design and protection type
  14. Possibility of integrating decentral intelligence in the frequency converter

2. Environmental details

  1. Installation height, ambient temperature
  2. Cooling requirements, cooling options
  3. Climatic conditions, such as humidity, water, dirt, dust, gas-es
  4. Special regulations, e.g. for mining, the chemical industry, the ship building industry,food technology
  5. Acoustic noise

3. Mains

  1. Mains voltage, voltage fluctuations
  2. Mains performance
  3. Mains frequency fluctuations
  4. Mains interference
  5. Short-circuit and overvoltage protection
  6. Mains drop-out

4. Maintenance, operation, personnel

  1. Training and instruction of operators
  2. Maintenance
  3. Spare parts/spare units

5. Financial criteria

  1. Purchase costs (components)
  2. Space requirement, integrated installation, design
  3. Installation costs
  4. Commissioning of the system
  5. Set-up costs
  6. Operating costs
  7. Efficiency of the system (frequency converter and machine)
  8. Reactive power requirement and compensation for harmonic loads
  9. Product lifetime

6. Protective measures for operators/converter/motor

  1. Galvanic isolation in accordance with PELV
  2. Phase drop-out
  3. Switching at the converter output
  4. Earth and short-circuit protection
  5. Motor coils to reduce voltage rise times
  6. Electronic thermal monitoring and connection of thermistors

7. Standards/regulations

  1. National DIN, BS, UL, CSA, VDE, European EN
  2.  International IEC, CE, etc.

8. Environmental considerations

  1. Ability to recycle the product
  2. Manufacturing practice
  3. Energy saving factors

Also important…

Using this checklist a frequency converter can be selected which covers most of the items as standard, but you should also double check whether:

  • The converter has mains or intermediate circuit chokes in order to greatly reduce mains interference
  • A RFI filter for class A or B is standard or has to be purchased separately
  • Motor derating is required if a frequency converter is used
  • The converter itself is protected against earth and short-circuit
  • The converter reacts adequately in a fault situation.