Energy Efficient Drives for HVAC Fans

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Optimize comfort and energy consumption in building ventilation

With user-friendly interfaces, distributed intelligence and reduced power consumption, Danfoss AC drives optimize the performance of fans.

The VLT® HVAC Drive and VLT® Refrigeration Drive convert velocity pressure sensor values into flow values, enabling setup based on fixed flow or fixed differential flow. This optimizes both comfort and energy consumption. To improve comfort levels even further, drives connected to fans can be set to avoid the frequency bands which create resonance and damage in the ventilation system.

Extended building management system capacity

When integrated into a building management system network, to extend the capacity of the controller, all HVAC drive I/O points are available as remote I/Os. For example, room temperature sensors (Pt1000/Ni1000) can be directly connected to the system. 

Improved air-handling performance

The VLT HVAC Drive and VLT Refrigeration Drive are fitted with a built-in Smart Logic Controller and four auto-tune PID controllers to control air-handling functions with fans, valves and dampers. The direct digital controllers of the building management system are released and valuable data points are saved lowering air-handling costs.

The VLT HVAC Drive handles logical rules and input from sensors, real-time functionality, and time-related actions. This enables the AC drive to better control a wide range of functions:

  • Weekend and working day schedules
  • Cascaded P-PI for temperature control
  • Flow balancing between fresh and outlet air
  • Belt monitoring – from the relation between current and speed, the AC drive is able to reliably recognize a broken belt. Lack of air flow is detected immediately so that action can be taken to reduce costs and downtime 

Safety in hospital ventilation

Hospital ventilation has strict requirements regarding safety, compliance and efficiency. Danfoss provides AC-drive solutions for fire and smoke safety, heat dissipation, harmonic mitigation, and EMC and seismic compliance.

Fail safe with no trips

In hospitals, failure for any reason can jeopardize lives. Drives powering pumps and chillers must be extremely reliable and virtually immune to mains supply disruptions. To achieve this reliability, Danfoss AC drives are designed to ignore voltage sags and even short outages, maintaining full performance at all times.

Protect applications and operators 

The VLT® HVAC Drive FC 102 provides the STO (Safe Torque Off) function in compliance with ISO 13849-1 PL d and SIL 2, according to IEC 61508 / IEC 62061. In high demand applications, this can be expanded with the VLT® Safe Option MCB 140, an external module that provides functions such as Safe Stop 1 (SS1), Safely Limited Speed (SLS) and Safe Maximum Speed (SMS), control of external contactors and safety door monitoring and unlocking.

Reliable harmonic mitigation

While AC drives increase precision, save energy and extend application lifetime, they also introduce harmonic currents to the hospital grid. If not kept under control, harmonic currents can affect the performance and reliability of generators and other equipment.

To ensure minimal disturbance, read more about our harmonics application know how, software tools and harmonic mitigation solutions.

Tunnel ventilation

Metro and motorway tunnel operators demand strict ventilation performance for safe operation and optimized cost of ownership. The VLT HVAC Drive offerings, from low to high power, fulfill smoke and fire safety requirements and comply with seismic regulations. All our units offer the same HVAC-dedicated functionalities, standards compliance and compatible soft starters, filter and fieldbus communications options.

Airport ventilation

With hundreds of thousands or even millions of passengers annually, ventilation is a top priority for international airports. To improve traveler comfort and safety, and to combat rising electricity prices, drives are increasingly being used to control and optimize the operation of air-handling units and reduce energy consumption.

VLT HVAC Drives extend from low- to high-power solutions. They come equipped with HVAC-dedicated functionalities and compatible soft starters and filters for EMC and harmonics mitigation. And the complete range of fieldbus communications options enables effective integration with the building automation system.

EC+ Concept

When building an HVAC system, to get the highest performance and system efficiency, the individual components – motor, drive and fan – need to be flexible and broadly compatible with each other. For instance, if you specify a high-efficiency motor that is only compatible with lower efficiency fans, the overall system efficiency would suffer and would not reflect the high performance – and investment – in the individual components.

Danfoss Drives’ EC+ concept allows ventilation system designers to combine a VLT® HVAC Drive with the most efficient fan and permanent magnet motor.

Advantages of the EC+ concept

  • Free choice of motor technology: PM, asynchronous or synchronous reluctance with the same AC drive 
  • Device installation and operation remain unchanged
  • Manufacturer independence in the choice of all components
  • Superior system efficiency thanks to a combination of individual components with optimum efficiency
  • Retrofitting of existing systems is possible
  • Wide range of rated powers for standard, PM and synchronous reluctance motors

World’s greenest hotel uses 60% less electricity

Designed for sustainability, Crowne Plaza Copenhagen Towers is truly engineering tomorrow, with 60% lower electricity consumption than comparable hotels operating conventional energy technology, in 2015. Deploying the best environmental and energy technology, the hotel comes close to achieving carbon neutrality.


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