Harmonic filters The continuation of our “Network harmonics” series [1] presents an article about AC harmonic filters. We explain the purpose of harmonic filter. Different types of harmonic filters are shown. Several design considerations are discussed. Main items are illustrated with figures and pictures. Grid side filters are covered in Read more
VFD harmonic spectrum Introduction After the theoretical introduction [1] we jump to variable frequency drives as sources of harmonics. This post is about VFD harmonic spectrum. As already mentioned, VFDs belong to non-linear devices with non-sinusoidal currents and/or voltages that they draw from the grid or inject into the grid. 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
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
Topics you would like to read about in 2020 Happy and prosperous new year from MB Drive Services! We would like to thank all our readers for your interest, support, comments etc. The year 2019 was a true success. Our blog reached over 11’000 views from more than 2’800 readers. Read more
Blast furnace plant Dolni Vitkovice In this series we look into industrial and utility plants that benefit or could benefit from the usage of medium voltage variable frequency drives. Today our excursion leads us to a former blast furnace plant Dolni Vitkovice in Ostrava, Czech Republic [1]. Previous Next The Read more
Experience with IGCT based VFD Introduction This is a continuation of our Reliability and availability series. To access all posts in this series please click here. In today’s post we will share an industrial experience with medium voltage IGCT based VFD. IGCT as heart of high-power frequency converter is used Read more
#LCI versus VSI:Part 4: Comparison (continue) Our series LCI versus VSI belongs to some of the most popular in this blog. We talk about the main medium voltage high power VFD technologies, Load-commutated Inverter (LCI) and Voltage Source Inverter (VSI), and compare them in various aspects. This post is a Read more
VFD transformers and harmonics Introduction The next post in our series discusses VFD transformers and harmonics. We have already learned what harmonics are and how they impact the supply grid (Network harmonics – intro). In this series we look more specifically into harmonics and their impact on VFD transformer. Motivation Read more