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Making modern living possible
Variable Speed Drive Compressors
NLV-F and BD150F How to start?
General:
The Danfoss variable speed compressors NLV-F and BD150F serve the possibility to adjust the refrigeration capacity according to the load by controlling the motor speed.
The compressors are highly optimized with very high motor as well as mechanical efficiency. Tests have shown improvements in energy consumption up to 30 %, depending on the system design.
Application:
The NLV-F compressors are designed for nominal voltage 100-127 V at frequency 50-60 Hz and refrigerant R 134a at medium to low evaporating temperatures (MPB/LBP) for commercial appliances.
The BD150F compressor is designed for nominal voltage 220-240 Volt at frequency 50-60 Hz and 300 V DC with refrigerant R 134a and low evaporating temperatures (LBP) for e.g. mobile cooling.
Selection:
Controlling the compressor speed means that the compressor selection is different to standard compressors. The model is chosen according to the capacity at max. speed. This capacity will cover the load at max. ambient temperature or at pulldown. This max. capacity will be chosen similar to the rated capacity of a standard single speed compressor for the same appliance. During normal cycling operation the compressor typically runs at minimum speed, giving the highest COP, and during peak load operation at maximum speed. The advantages by doing this are:
•a smaller compressor in terms of displacement is needed
•longer running periods at load conditions with higher evaporation temperature and lower condensing temperature, giving higher compressor COP. Overall system efficiency increases
•lower rpm - lower noise level
Variable speed programme:
The compressor programme is under constant consideration and extension of the capacity range is under development.
The performance data will be updated in the individual datasheets, to be found on the homepage compressors.danfoss.com
Evaluation samples for special purposes, and refrigerants other than
R 600a and R 134a, are possible to establish in development cooperation projects.
February 2010 |
DEHC.EI.300.B3.02 / 520N1002 |
2 |
Design:
Electrical:
The compressors are equipped with permanent magnet rotors (PM motor) and 3 identical stator windings. The electronic unit is mounted directly on the compressor and controls the PM motor.
Mechanical:
All other components are based on our normal compressor programme.
All R 134a compressors are charged with ester oil and are only approved for use with this oil and refrigerant. A blue stripe and the text 'R134a' on the compressor label identify the compressors for this application.
Design limits:
In order to secure the lifetime of the compressors, the appliances have to meet some design criteria.
The compressor has to start and work properly through pressure peaks obtained in the highest ambient temperature and lowest obliging voltage. At this peak load the condensing temperature must not exceed 70°C.
At stable operation conditions the condensing temperature must not exceed 60°C.
These limits are the same for our fixed speed compressor ranges and secure a protection of valves, gaskets, oil and motor insulation
Electronic unit:
The variable speed compressor motors are electronically controlled. No attemp must be made to start the compressor without a complete electronic unit, as specified in the data sheet for the compressor type in question.
The electronic unit has a built-in overload protection as well as thermal protection. In case of activation of this protection the electronic unit will protect the compressor motor as well as itself.
When the protection has been activated, the electronic unit automatically will restart the compressor after a certain time.
The electronic unit provides the compressor with high starting torque (HST) which means that a pressure-equalizeation of the system before start is not necessary.
Power supply connections :
Mains is connected to terminals L and N. To facilitate connection with other units the control unit is provided with parallel connector pins to L and N. Protective earth is connected to the compressor shell.
February 2010 |
DEHC.EI.300.B3.02 / 520N1002 |
3 |
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