The Turning Point: The Wilo-Star-E
The first step towards the electronic age was the development of the electronic multi-speed switch and the introduction of the AS control system at the beginning of the 1980s. However, one disadvantage of this electronic switchgear was the external switchbox that housed the control electronics. This led to additional expense during assembly and commissioning because the switchgear and any sensors had to be wired with the pump. In addition, there was a risk of making mistakes with the wiring. A solution was therefore sought in which the control electronics are integrated in the pump and no additional wiring is required.
Multiple technological challenges had to be resolved in the course of development:
The electronics had to be small enough to fit into a housing on the pump. A frequency converter for a motor with roughly 4 kilowatts required as much space as a linen chest and also had to be cooled using oil. Since it was impossible to attach these electronics to a pump, Wilo initially concentrated on pumps with a much lower output. The miniaturisation of electronics had progressed far enough in the mid-1980s that the control and power electronics could be integrated in a housing on the pump.
The electronics mustn’t cause any additional noise. The insight gained from the AS08 electronic switchgear was that the phase angle control used for it was not entirely noise-free. In some systems, the humming noises could be transmitted throughout the entire building. The developers needed a solution that operated as quietly as possible.
In order to control the pump in a sensible way, the hydraulic variables of the pump, differential pressure and/or volume flow had to be known. In order to control the differential pressure of a pump to a desired value, you need to know the differential pressure. It’s similar to a car. If you want to drive 50 km/h in the city, you have to know the current speed of the vehicle in order to assess whether you are driving too fast or too slow. With the AS08 switchgear, this task was solved by means of an external differential pressure sensor. However, it was expensive and also had to be wired on-site.
After conducting extensive research and overcoming the last difficulties, Wilo succeeded in developing a continuous pump with fully electronic control in 1987. Wilo-Star-E*, the world’s first electronically controlled heating circulator, was introduced on the market in 1988. Thanks to the electronic control, this innovation in pump technology offers not only greater convenience, but also energy savings of up to 50 per cent.
* At this time, the series name was given before the company name, e.g. Star-Wilo.