VLT Drives Applications (VIDEOS)
Some of the interesting applications done with Danfoss VLT drives:
- VLT drives in large desalination plant
- VLT drives control cooling tower fans
- VLT control optimizes spindle speed in Indian textile factory
- VLT frequency converters drive bagage handling system
- VLT Drives Save 78% Energy in Chester Zoo
1. Details of the machine to be controlled
- Required plant/machine characteristics
- Torque characteristics, stalling torque, acceleration torque
- Speed control range, cooling
- Power consumption of the converter and the motor
- Operating quadrants
- Slip compensation (dynamic)
- Required ramp-up and ramp-down times
- Required braking times, brake operating time
- Direct drives, gears, transmission components, moment of mass inertia
- Synchronisation with other drives
- Operating time, controls
- Computer linkage, interfaces, visualisation
- Design and protection type
- Possibility of integrating decentral intelligence in the frequency converter
2. Environmental details
- Installation height, ambient temperature
- Cooling requirements, cooling options
- Climatic conditions, such as humidity, water, dirt, dust, gas-es
- Special regulations, e.g. for mining, the chemical industry, the ship building industry,food technology
- Acoustic noise
3. Mains
- Mains voltage, voltage fluctuations
- Mains performance
- Mains frequency fluctuations
- Mains interference
- Short-circuit and overvoltage protection
- Mains drop-out
4. Maintenance, operation, personnel
- Training and instruction of operators
- Maintenance
- Spare parts/spare units
5. Financial criteria
- Purchase costs (components)
- Space requirement, integrated installation, design
- Installation costs
- Commissioning of the system
- Set-up costs
- Operating costs
- Efficiency of the system (frequency converter and machine)
- Reactive power requirement and compensation for harmonic loads
- Product lifetime
6. Protective measures for operators/converter/motor
- Galvanic isolation in accordance with PELV
- Phase drop-out
- Switching at the converter output
- Earth and short-circuit protection
- Motor coils to reduce voltage rise times
- Electronic thermal monitoring and connection of thermistors
7. Standards/regulations
- National DIN, BS, UL, CSA, VDE, European EN
- International IEC, CE, etc.
8. Environmental considerations
- Ability to recycle the product
- Manufacturing practice
- 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.
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