DC component in VFD transformers Certain VFD topologies may generate direct current (DC) component on the grid side. There is a general concern about how such DC component affects the performance of the VFD transformer. In this post we discuss Read more…
Hydro power plant Slapy (CZ) In this article we invite you to discover hydro power plant Slapy in Czech Republic – the first large construction of Vltava cascade after world war II. Slapy is situated in Central Bohemia, approx. 25 Read more…
Skoda 9Tr: Impressions from a ride In this post we would like to share some expressions from the ride with historical trolleybus Skoda 9Tr (spelled ŠKODA 9Tr in Czech with a special character above “S” pronounced “sh”). It took place Read more…
How strong is a strong grid? When evaluating the impact of a VFD on the electric grid, particularly the harmonic distortion, we often talk about “strong grid” or “weak grid”. These terms may be a bit vague or at least Read more…
What is the right strategy to retrofit fix-speed motor into VFD operation? As addressed in our previous post, a retrofit of a direct on-line (DOL) machine into VFD duty may be a very attractive choice [1]. This post focuses a Read more…
Purpose of electrostatic shield What is the electrostatic shield and why is it actually used? This article briefly explains the purpose of electrostatic shield in VFD input transformers [1]. First note that there are several terms being used for what Read more…
Benefits of transformer rental service Transformer rental aims to maximize the availability of drive system and reduce the cost impact as much as possible. In this post we will briefly describe the benefits of transformer rental service. Reliability of transformers Read more…
Torque meter in variable speed drive systems Unlike electrical quantities the measurement of torque is not an easy task. Hence in most cases the torque is not measured directly but calculated (estimated) from electrical signals. But what if you need Read more…
Traction converters Traction power electronic converters play a key role in modern transportation. Unlike industrial converters they face slightly different and specific challenges with regards to design, operation mode or safety.In this post we provide a brief look into the Read more…
4 common defects of liquid immersed transformers In this post we present some of the common defects appearing in liquid immersed transformers. As stated at the end of this article always adhere to all applicable safety rules and regulations. Leaks Read more…