How do system parameters impact the grid harmonic distortion? VFD as a non-linear load produces harmonics that are injected into the grid and cause harmonic distortion. The level of harmonic distortion depends on the type of VFD, specifically the rectifier Read more…
What is the difference between dv/dt filter and sine filter? Almost every voltage source inverter (VSI) has some kind of inverter output filter. Design of the output filter has major impact on the drive characteristic and performance. For this post Read more…
How are the motor load points defined? Customer is often interested in defining the performance (e.g. losses and efficiency) of a motor drive for specific operating points. But how are the motor load points defined? Over the years working with Read more…
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…