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
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.
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
VFD transformers: Multi-winding design Today we look at the design of multi-winding VFD transformer feeding variable frequency drives. These VFD transformers are often classified in the category of ‘special transformers’. What does it mean? Why are they special? If you want to get these answers and a little insight into 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