VFD versus gas turbine In this post we are going to compare two variable speed drive solutions: an electric drive consisting of a VFD and a motor and a gas turbine. Gas turbine is an internal combustion engine, i.e. an energy conversion device that converts energy stored in the fuel Read more…
To Gear or not to Gear? “To Gear or not to Gear: That is the question!” Dear readers, it is April 1, the Fool Day. However, we are not going to fool you. Instead, we have just allowed ourselves to paraphrase the famous quote by Shakespeare from Hamlet, Act 3 Read more…
It Is Webinar Time! Update: Dear visitors, Thank you for your interest. Please note that the webinars are not available anymore. We will consider making a new webinar series in the future. Feel free to contact us in case of any questions. Thank you for your understanding. With the spring Read more…
Part 2: Overview of motor starting methods Electric motors as work horses of the industry are extensively used since decades. The topic of motor starting is therefore well known and various starting methods had been developed. This article presents an overview of most common motor starting methods. Which solution to Read more…
Selection of a variable frequency drive In this post we walk through some aspects regarding selection of a variable frequency drive. Variable frequency drives, often abbreviated as VFD, VSD or ASD, are means to achieve energy savings [1] and to enable position, speed or torque control of electric motors. Meanwhile, Read more…
Advantages of liquid cooled drives This article deals with liquid cooling for high power variable frequency drives (VFD). What is the principle of liquid cooling? What kind of liquid can be used for cooling? What are the advantages of liquid cooled drives? Continue reading this post on advantages of liquid Read more…
VFD testing: Introduction Abstract This new series on VFD testing will guide you through various aspects of testing of variable frequency drives (VFD) and drive systems. We will discuss tests required by standards (particularly IEC), factory acceptance tests, site acceptance tests and system tests, such as full load combined test 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…
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…