VFD transformers: Introduction After reading this blog post you should understand the purpose of a VFD transformer and the differences between distribution/power transformer and a VFD transformer. Let’s start with the definition of a VFD transformer: This term refers to the input isolation transformer that supplies the rectifier section of Read more…
Literature on Variable Frequency Drives, Power Electronics and related subjects The purpose of this blog is to provide useful information about Variable frequency drives (VFD) and power drive systems that you might appreciate when working in this field (specifying, selecting, purchasing, operating, servicing/retrofitting, researching or developing tasks). The blog intentionally Read more…
Network harmonics:Introduction Apart from the numerous advantages of variable frequency drives, such as precise speed or torque control, smooth motor starting or energy savings, this technology also comes with specific challenges. One of them are the network harmonics. The good news is that there is a solution. Actually, there are Read more…
VFD versus fluid coupling Today we open a topic that might polarize our readers: Comparison between variable frequency drive (VFD) and a fluid (hydrodynamic) coupling. Of course, this blog is dedicated to VFDs. Nevertheless, we intend to provide an objective benchmark as far as possible. Please note that there is Read more…
Encoders in motor drive applications What is the purpose of encoder? When is it needed? What types of encoders are being used? This post shall answer some of these questions. VFDs are used to control the motor speed or motor torque. The actual speed is either estimated (speed sensorless control), Read more…
Solutions for variable speed control: Introduction This post introduces the most common solutions for variable speed control in industrial applications. Before starting with the topic we want to refresh the meaning of some commonly used abbreviations. Variable speed drive (VSD) – A general term for anything that varies the speed Read more…
Reliability and availabilityPart 5: Factors impacting availability High availability is a key measure for many companies in today’s world in order to be competitive and to survive. If a supplier cannot deliver in contractually agreed date (delay) or cannot deliver the agreed quantity, he might face hard financial consequences (penalties, Read more…
Input power factor and reactive power consumption The focus in all energy efficiency initiatives is to minimize the losses, improve the system efficiency and reduce overall power consumption. With “power” people usually refer to active power and this is basically correct. Main purpose of VFD is to reduce active power. Read more…
Derating and uprating factors What is the power rating of the specific VFD? An indicative value is provided in the technical catalog or brochure. This value shall refer to certain operation conditions, among others the temperature of cooling medium (air or liquid), content of anti-freeze additive (usually some type of Read more…
How to choose a medium voltage VFD:Life cycle cost What is life cycle cost (LCC)? The definition from business dictionary (www.businessdictionary.com) says: Sum of all recurring and one-time (non-recurring) costs over the full life span or a specified period of a good, service, structure, or system. In includes purchase price, Read more…