Powerstream Screw Inverter

Featuring a combination of inverter-fed and fixed-speed compressors, the range offers high energy efficiency throughout the entire operating range



Full-envelope efficiency

Powerstream Screw Inverter is a solution best matched to meet a growing demand for cooling, as well as for cooling plants with varying load. These water-cooled chillers are built with advanced, carefully selected components, ensuring continuous trouble-free operation.


With inverter-driven and fixed-speed screw compressors piped to a single refrigeration circuit and regulated by the advanced control logic, Powerstream Screw Inverter chiller precisely matches the actual cooling load. Smooth capacity modulation enables substantial energy savings and provides precise thermal control. These chillers are particularly suitable for use in variable-flow applications.

  • Precise capacity control with inverter technology

  • Excellent full and part load efficiency

  • Feature-rich control software

  • High seasonal energy efficiency

  • Lower operating costs

  • Proven reliability

Features and advantages

Design and components


Precise capacity control

Powerstream's compact semi-hermetic screw compressors are distinguished by a further improvement in energy efficiency at full and part load conditions. Accordingly, these compressors exceed the international efficiency standard of compact screws with respect to the seasonally weighted energy requirements to an even higher degree than before.

Each unit in the range equipped with a pair of compressors on a single circuit and starts with the one driven by the inverter-fed motor. As the cooling demand exceeds its capacity, the control system of the chiller starts up a fixed-speed compressor and adjusts the speed of an inverter-driven compressor accordingly to the actual load. When the cooling demand decreases, the control system stops a fixed-speed compressor and regulates the speed of an inverter compressor as required. Additionally, the chillers feature low in-rush current, hence lowering the installation costs.


Centralized chilled water plant control


The control hub of Powerstream chillers is a sophisticated controller with advanced software developed for efficient operation of water-cooled chillers. It manages and optimizes the chiller’s performance, giving the complete control over the system for plant operator.


Control software can be directly linked to the existing building management system. Integration with a BMS allows collecting and analyzing operating data of chilled water plant and helps to maintain optimal equipment settings, saves energy, identifies trouble-prone areas, provides maintenance schedules and generate safety and security alarms.


For the efficient operation of multiple units on a single chilled water plant, the sequencing software permits interlinked operation of the complete system, thus providing optimal temperature control and minimal energy consumption.


Chillers can be configured for constant or variable flow depending on a configuration of a chilled water system. For the systems with a primary-only circuit, constant pressure differential or constant temperature differential flow control can be selected, while constant temperature differential control is available for primary/secondary systems. Flow control logic dynamically adjusts the pump speed based on the actual load, thus optimizing pump energy consumption and ensuring the stable operation of the chilled water plant. The control system is able to operate with a single chiller or multiple chillers.


Adopted for part load conditions

Allows high evaporation temperatures

The shell and tube evaporator used in Powerstream design offers extremely high evaporating temperatures for a given supply water temperature and optimized for R134a refrigerant. The heat transfer rate of the evaporator enhanced with internal refrigerant side tube grooving and optimally positioned baffles.


The tube bundle composed of a series of pre-modeled U-shaped tubes enabling the free expansion of the whole unit independently from the shell. Internal baffles in the water circuit optimize the flow while keeping pressure drop to a minimum. Reduced baffle spacing ensures high heat transfer at low flow rates, as well as for brine operation.


Optimized for R134a refrigerant

Easy of maintenance


Powerstream chillers feature newly developed shell-and-tube water-cooled condensers optimized for R134a refrigerant to provide the best possible efficiency. With high-grade finned tubes, the new design of the internal baffles and shell, these condensers provide lower condensing temperatures and maximum efficiency with a low cost per kW, as well as the shorter length and reduced weight.


Optimized water flow also reduces the risks of fouling and erosion of the heat exchanger, while reduced pressure drop enables savings on pump energy. New heat exchangers allow the extended range of condensation temperatures, making the chiller suitable for almost any kind of applications.

We recommend using Bora or Mistral series dry coolers with Powerstream chillers. These dry coolers are optimized for use with water-cooled chillers, offer high performance and enable low water temperature difference.

Dry cooler selection

Bora series

Bora series is well-suited for urban locations due to their low sound emission, as well as for high-polluted areas and coastal installation due to the high corrosion resistance of microchannel heat exchangers used in the unit design. For the installations in hot climate zones, we recommend Bora dry coolers with evaporative pads. Evaporative dry coolers lower temperature of the air entering cooling coils, thus enabling lower condenser water temperatures and providing energy savings on compressors of up to 35%.

Mistral series

Mistral series dry coolers equipped with finned tube heat exchangers with internally grooved copper tubes and are ideal for any kind of industrial and commercial applications. These dry coolers are extremely robust, simple by design and perfect in the specification.


Cooling capacity



Up to 5.80


Up to 8.63









ErP compliance


Related products



Reliable and sustainable water-cooled chillers equipped with compact screw compressors and dual refrigerant circuits. Available with the cooling capacities from 600 to 1200kW

  • facebook-aaaaaa
  • linkedin-aaaaaa
  • twitter-aaaaaa
  • googleplus-aaaaaa

Kaltra Innovativtechnik GmbH

Max-Reger-Str. 44
90571 Schwaig

Email: info@kaltra.de
+49(0)911 715 32021

VAT: DE300943964

Kaltra is a customer-focused developer and supplier of reliable, energy efficient thermal management equipment and solutions.


From the professionalism of our research and development engineers to the wide experience of our service team, we are dedicated to delivering you the best service possible.

Read more

© 2014-2019 Kaltra. All rights reserved.