VFD transformers: Differential protection Differential protection of VFD transformers might be a controversial topic. The more a reason for us to bring it up, explain the principle, describe the advantages and drawbacks and provide our view and recommendation for the users. We hope that this article will be useful source Read more
Transformer short circuit impedance Short-circuit impedance of a transformer, impedance voltage or just impedance are terms often used as synonyms. They describe one of the most important transformer parameter: short-circuit impedance. This article, as part of our VFD transformers series [1], presents the short-circuit impedance from VFD design perspective. After Read more
Transformer winding connection, clock number and vector group This article explains the winding connections, clock number and vector group of phase-shifting transformers used to supply variable frequency drives (VFD). Motivation Some of the most common keywords that bring the readers to our webpage are associated with multi-winding transformers, their connection Read more
VFD transformers: Your questions The articles from VFD transformers [1] series belong to the most frequently read posts in our blog. It seems that many visitors find us through internet search using keywords such as “converter duty transformer”, “24 pulse drive phase shift”, “extended delta transformer”, “12-pulse phase-shifting transformer”, “three Read more
Overvoltage protection of transformers This is the continuation of [1] that made an introduction into protection of VFD transformers. The focus of this article is on overvoltage protection. Particular attention is paid to very fast transient overvoltages caused by switching of vacuum circuit breakers. Keep reading to learn about the Read more
Protection of VFD transformers In the introduction to this series we have explained the differences between a distribution/power transformer and a VFD transformer [1]. Due to different design, construction and operation of VFD transformers the protection requirements shall be adapted as well. While many end users, system integrators, EPCs and Read more
Integrated versus external transformer Modern variable frequency drives offer two options: integrated transformer or external transformer. How do these options compare? Which one is a better choice? INTEGRATED TRANSFORMER EXTERNAL TRANSFORMER There is no general answer. Instead, it depends on several aspects and project specific conditions. This post will walk Read more
VFD transformer rental This post provides a brief description of our service “VFD transformer rental”. You will learn what the service is about, how it works, what is the target application etc. The contact form is located in our section Services (click here). Introduction Transformers are mainly used in power Read more
VFD transformers and harmonics Introduction The next post in our series discusses VFD transformers and harmonics. We have already learned what harmonics are and how they impact the supply grid (Network harmonics – intro). In this series we look more specifically into harmonics and their impact on VFD transformer. Motivation Read more
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