VFD control: An introduction In this post we introduce basic thoughts on VFD control. Some of you asked deeper questions about different motor control strategies and their benchmark. Such comparison will be subject of a separate post, resp. a dedicated motor control series. Today’s article provides a base for further 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…
Does a VFD pay off? In turbulent times companies are cautious of making investments. However, exact these periods are times when specific companies set apart from the others by making smart decisions. VFD can reduce the energy consumption, make the production more flexible and improve the quality of the products 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…
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.