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The Quantum Leap in Pump Technology: The Wilo-Stratos

In 2001, the world’s first high-efficiency pump for heating, air-conditioning and cooling applications was presented by Wilo. The “Wilo-Stratos” consumes up to 80% less electricity than uncontrolled circulators. When the European energy label for heating pumps was introduced in 2005, this pump series was the reference for the energy efficiency class A.

Continuously modular bus concept

The operating principle of an electronically commutated direct-current motor is fundamentally different from that of an asynchronous machine. The now-common term EC motor is derived from the English description: electronically commutated motor. While an asynchronous machine can be operated directly on a single-phase or three-phase alternating current network, the operation of a brushless direct-current motor requires control electronics.

The rotor of the brushless direct-current motor consists of a magnet. This magnet can be rotated by generating an external magnetic field that matches the alignment of the magnet and lets it rotate around the rotor. To achieve this, copper coils that can be energised individually are installed in the stator. A copper coil with a current flowing through it also generates a magnetic field. By making sure that the copper coils are energised one after the other in a certain direction of rotation, a magnetic field that rotates around the rotor is generated. This magnetic field pulls the rotor along and causes it to rotate.

The targeted energisation of the copper coils that generate the revolving magnetic field in the stator is promoted by means of an electronic control, which is known as the commutation electronics. The major energy advantage of the EC motor results from the permanent magnet motor. In contrast to other motors, these magnets do not require any energy for magnetisation.

The idea of the Wilo engineers to use EC motors for pumps was driven by the following superior properties of this motor:

  • considerably greater energy efficiency than asynchronous motors due to lower power consumption

  • greater power density, i.e. a more compact design (a motor with the same output is smaller)

From a technological perspective, the idea to use EC motors for pumps involved a number of challenges that had to be solved gradually over the course of multi-year technological development.

Display with “red button technology” that can be adjusted independent of the location

The Wilo-Stratos was an important milestone for the company. Using a high-efficiency direct-current motor allows to achieve pioneering levels of efficiency and offer a huge power saving potential of up to 80 per cent compared to uncontrolled heating pumps. The term “high efficiency” was unknown prior to the market introduction of the Wilo-Stratos in 2001. Thanks to the outstanding technology and a successful marketing campaign, Wilo shaped this now-common generic term for extremely efficient pumps.

The greatest possible performance is achieved by using the smallest amount of energy possible. This conserves resources and protects the environment in the long term. Back in 2005, Wilo voluntarily introduced the energy label of the European Ecodesign Directive (ErP directive). This binding law led to the ultimate breakthrough of the Wilo-Stratos on the market in 2013.