What is SSTI and why it shall be studied? In this short post we provide a little introduction into what is SSTI and how it can be linked to variable frequency drives (VFD). The post also explains the motivation for Read more
What is the definition of low voltage and medium voltage VFD? We all probably know that variable frequency drives (VFD) can be classified into two groups based on their voltage: low voltage VFD and medium voltage VFD. But what voltage Read more
What type of asynchronous motor suits the best for VFD duty? Asynchronous motor is sometimes called the work horse of the industry. And this nickname is well earned. It is because millions of such motors are utilized in different applications Read more
Short circuit current contribution of a VFD Electric motors and generators contribute to the total fault level at the connection point. Their short circuit current is typically in the range 4…6-times the nominal current of the machine. How is the Read more
How conservative is Oil & Gas industry? Oil & Gas industry is known for its conservative attitude. Such statement is principally correct. However, it depends what you understand under being conservative. Moreover, are there any exceptions? While being generally conservative, Read more
How much energy is stored in a pumped storage power plant? Reduction of carbon footprint is a key objective of almost all developed countries. To make the transition to a more renewable power generation successful, sufficient energy storage capacity is Read more
Fuseless is not useless This post addresses the VFD protection concept and particularly the concept eliminating medium voltage fuses – so called fuseless design. We explain the advantages of such approach and why it is definitely not a useless feature. Read more
When is transformer tap changer needed? The input isolation transformer in a drive system may be equipped with a tap changer. Such device provides some flexibility but adds cost and potentially also complexity to the transformer design. Thus, the question Read more
High-speed drives: VFD perspective In the introduction to high-speed drives [1] we have briefly described the design variants of semi high-speed and high-speed motors. The impact on construction of the motor is significant. High-speed motors can be quite different compared Read more
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