Jussi Tamminen

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While the cause-and-effect chains of inverter-induced bearing currents have been well understood today, not much is known about the damage mechanism inside the bearings. Research has suggested that the bearing degradation is approximately proportional to the frequency of occurrence of the bearing currents. For bearing currents that occur statistically(More)
Modern frequency converters allow energy efficient operation of induction-motor-driven systems such as pumps and fans. In addition, they can be used as a sensorless monitoring unit for the pump and fan systems, as shown by previous studies. Sensorless diagnostics of induction-motor-driven systems relies on the accurate estimation of the rotational speed,(More)
Energy harvesting or scavenging from environment is being researched intensively. The main motivation of the research is to develop a maintenance free energy source for ubiquitous electronics, such as wireless sensors or sensor networks. The on-line condition monitoring of electric motors requires also sensors that are installed at the motor. In this case,(More)
Pumps are widely used in industrial applications, and they account for nearly a quarter of the electric energy consumption in the European industry. Pumps are often overdimensioned or they may be driven inefficiently, which causes unnecessary energy costs. If the pump drive is not equipped with appropriate measurements, inefficient pump operation may remain(More)
A wrong rotational direction of a centrifugal device is detrimental for the service life and energy efficiency of the device. However, in some cases, visual inspection of the correct rotational direction is difficult or even impossible. This paper presents a sensorless method that can detect the correct rotational direction of a centrifugal device. The(More)
Often, the components of a pumping system are not selected from the perspective of the total system, as the individual components are selected using different programs. In this paper, a selection tool that optimizes the energy conversion efficiency of a pumping system according to actual process requirements is introduced. The tool requires only the catalog(More)
Pump, compressor and fan systems often have a notable energy savings potential, which can be identified by monitoring their operation for instance by a frequency converter and model-based estimation methods. In such cases, sensorless determination of the system operating state relies on the accurate estimation of the motor rotational speed and shaft torque,(More)
Operational state of a centrifugal pump directly affects the resulting energy consumption of the pump. Frequency converters (VSDs) allow the sensorless estimation of the operational state of a centrifugal pump, offering new possibilities for the diagnostics and control of pumping systems. However, estimation of the pump operational state by the(More)