How to maximize the availability of your drive system Availability is one of the key criteria for the end users according to numerous surveys and direct feedback. Unplanned downtime is simply too expensive and shall be avoided. At the same time multiple redundancies may not be economically viable (high investment Read more…
VFD catalog rating You have surely noticed that most manufacturers have catalogs and brochures with tables listing their VFD types along with basic information such as rated output current, motor shaft power, cooling requirements, enclosure type, dimensions, weight etc. What is behind this VFD catalog rating and how to understand Read more…
Current source and voltage source inverter Current source and voltage source inverter are the two basic types of indirect frequency converters. Therefore, it might be very interesting to describe and compare both types. This article can also be seen as an amendment to the LCI vs VSI series [1] that Read more…
Dream VFD You may think that the title of this article – dream VFD – does not sound very serious. However, let us elaborate on the topic a bit. It actually is a serious question: How does your dream VFD look like? What are the features of your dream VFD? 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…
Case study on energy savings in variable flow fan systems.
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…
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…
#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…