E-mobility Our blog is generally focusing on medium voltage drive systems. However, we can’t ignore the trend and the huge potential of electromobility (e-mobility). Since the technology is based on electric motors, variable frequency drives and other power electronics we would like to contribute on this topic as well. Moreover, Read more
Protection of VFD transformers In the introduction to this series we have explained the differences between a distribution/power transformer and a VFD transformer [1]. Due to different design, construction and operation of VFD transformers the protection requirements shall be adapted as well. While many end users, system integrators, EPCs and Read more
Motor start with VFD Our experience shows that the VFD motor start is sometimes not fully understood. This post shall explain how motor start with VFD works, what are the main benefits and how does it compare to a direct on-line start. Abbreviations AFE = Active Front End DFE = Read more
Energy savings in pump systems: Case study 1 After introducing the way how energy and cost savings are calculated [1] we will demonstrate the theory on a real example from industrial practice. This article presents a case study of a boiler feedwater pump inside a thermal power plant. Let’s explore Read more
Case study on energy savings in variable flow fan systems.
Modern and historical public transportation in Pilsen Our excursion today leads us to Pilsen, Czech Republic. The city is located in western Bohemia. It was founded in 1295. The distance from Prague is about one hour. It is easily accessible by car (highway Prague – Nuremberg), by train (direct trains Read more
How to calculate energy and cost savings Our series on energy efficiency continues. The need for more energy efficient systems emerges day by day driven by increasing environmental concerns. Today’s post will guide you through calculation of energy and cost savings when utilizing a VFD in flow control. Energy savings Read more
Combined transformer Our recent post [1] walked the reader through the two main VFD transformer options: integrated transformer and external transformer. Today we will introduce a solution that aims to leverage on advantages of both solutions: combined transformer. The name might be a bit misleading. We can also call it Read more
Electro-mechanical interaction:Growing trend of vibration issues We have observed numerous vibration issues associated with rotordynamics in variable frequency drive systems across the industries. The trend is growing and this shall be a warning sign. There are multiple reasons for this trend. Here we name the most important ones from our Read more
Electro-mechanical interaction:Introduction Electric variable frequency drives provide lot of benefits in terms of energy savings, controllability and flexibility. But the VFD is just means to control the speed or torque of electric motors. The useful work is provided by the driven load such as e.g. pump, fan, compressor or mill. Read more