With user-friendly interfaces, distributed intelligence and reduced power consumption, Danfoss AC drives optimize the performance of fans.
Optimized comfort and energy consumption
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:
With multiple pump-dedicated control features and intelligent protection capability, Danfoss AC drives optimize production and protect the drive, the motor and the equipment in the system. They also ensure optimized liquid supply in the event of leakage or a broken pipe. Dedicated features include:
Pumps quickly reach minimum speed and fill the system without stressing valves.
Flow resistance is dependent on flow speed. To save energy, the AC drive eases the pressure when low flow is sufficient.
Auto-tuning of PI controllers
The drive learns from monitoring system response to its corrections, and calculates increasingly better P and I values to quickly restore precise and stable operation.
This built-in logic controls alternation between two pumps in duty/standby applications. Motion of the standby pump prevents the pump from sticking. An internal timer assures equal usage of the pumps.
Features, such as Automatic Energy Optimization, assure optimum magnetification in the motor.
Automation means less waste and better process control. Danfoss AC drives handle the most common bus protocols in the industry and integrate seamlessly into the overall control system.
Reduced wear and tear
The embedded Pump Cascade Controller distributes running hours evenly across all pumps. This keeps wear and tear on each individual pump to a minimum, enables optimal predictive maintenance scheduling and increases pump lifetime.
AC drive speed is reduced to ensure supply at a lower flow rate.
Dry pump protection
If a well runs dry or a pipe leaks, the AC drive detects that the pump is running below the desired pressure. The drive starts an alarm or performs another pre-programmed action to protect the pump.
No flow/low flow
If water circulation stops, the pump runs dry or a pipe leaks, the AC drive detects that the pump is running fast but is not fully loaded. The drive compensates the power supplied to the pump accordingly.
Intelligent heat management
Back-channel cooling systems ensure 90% of the heat is kept outside the control room. The creates cost savings as less energy is needed to provide air conditioning for the control room and fewer fans are required in the panel door.
Variable speed control of a chiller allows you to provide constant pressure regulation while matching the capacity to the actual need based on measurements in the system. Speed control is beneficial when an air compressor is running for long periods at partial load. Reduce operational costs by running applications at a lower speed which saves energy consumption. And reduce installation costs by optimizing the system and the compressor itself.
Danfoss AC drives ensure fewer starts and stops which reduces mechanical wear. And dedicated features, such as the ‘skip resonance’ function, allow you to easily identify for the drive the frequencies to prevent noise and damage.
Products for compressors include soft starters, high-power drives, AHF harmonic filters with a built-in cascade controller option, DC coils and PID controllers.
Start-up and peak load strategies
Start-up is the critical phase of compressor operation. The VLT Refrigeration Drive minimizes the number of starts required by varying the compressor speed to tune capacity during operation. The maximum number of start/stop cycles in a given period is configurable using the control panel.
135% starting torque
The VLT Refrigeration Drive delivers 135% of the rated starting torque for a 30-second period. During normal operation, 110% of the rated torque is available for 60 seconds.
To extend the drive lifetime, a pressure relief valve can be opened to allow the compressor to start up quickly with no load.
Smaller compressors with the same peak load
Brief peak loads can be handled by configuring the system with a smaller compressor, which the drive runs at up to 90 Hz. In this way, a larger compressor just to cope with peak loads is not necessarily required.
The VLT Refrigeration Drive continues to control fixed-speed compressors in situations where the variable-speed compressor fails. For a fail situation, the neutral zone is set by a special parameter "Fixed speed neutral zone", which enables fewer starts by expanding the neutral zone.
The VLT Refrigeration Drive supports connection of an ADAP-KOOL® LonWorks controller for P0 optimization.
Day and night control
Vary the compressor setpoint and evaporator fan speed schedules to match day and night loading, and avoid unnecessary energy consumption.
Condensation final temperature monitoring
By monitoring the floating head high pressure level control via temperature sensors, speed is reduced before the high pressure reaches a critical value.
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