This series brings topics answering basic questions around VFDs such as fundamental components of VFDs, drive system components, working principles, dimensioning considerations etc.
Why do VFDs sometimes trip during grid faults? Grid disturbances and faults appear now and then. And it is desirable that the VFD does not trip every time such event occurs. Thus certain immunity against grid disturbances is desired. In fact, many products claim to have a capability to withstand Read more…
KYDS: Know Your Drive System KYDS -Know Your Drive System – is our new program where you learn more about variable speed drive system and the most important system components (transformer, VFD, electric motor, cooling system, harmonic filter). Scope of KYDS The scope of the Know Your Drive System program Read more…
What is the difference between VFD and VDS? This article aims to answer one relatively simple question: What is the difference between VFD and VSD? As the question was raised again recently, we would like to deliver an understandable explanation. Let’s start with the abbreviations first to ensure that we Read more…
How to measure VFD efficiency Energy efficiency is high on the agenda. VFDs are enablers on higher efficiency in drive systems, especially in flow control. However, how to deal with VFD efficiency? In particular, how to measure VFD efficiency and verify the figures provided by the manufacturer? There is a Read more…
Active filter or AFE drive – What is a better option? When taking care of grid harmonics there are several technical solutions to choose from. You might stand in front of a dilemma: active filter or AFE drive? What is a better choice? Nowadays there are multiple approaches how to Read more…
How does VFD calculate the motor torque? Motor torque along with speed is the most important quantity that the VFD shall control. But how does the VFD measure or calculate the motor torque? What are the necessary inputs? Are there any extra sensors needed? Can every VFD perform the calculation Read more…
VFD switching frequency The heart of every variable frequency drive (VFD) is the power semiconductor. By switching on and off in a proper modulation scheme the frequency conversion functionality is achieved. Let’s look at various aspects of VFD switching frequency. Switching frequency of medium voltage VFDs Having medium voltage VFD Read more…
Enclosure protection – IEC vs NEMA In this short post we look into the subject of ingress protection (IP) of enclosures used in variable frequency drives, switchgears etc. First we explain the classification of ingress protection according to IEC standard (“European practice”). Afterwards we introduce the North American practice defined Read more…
What information belongs on a nameplate? Nameplate or rating plate is an inherent part of each drive system component, such as the transformer, variable frequency drive (VFD), electric motor etc. Therefore, it makes sense to spend few paragraphs on the topic. This post explains the content of information on a Read more…
Which one is your VFD hero? VFDs, together with their rotating partners (motors) perform lot of work behind the scene. As we already know, there are multiple VFD topologies available on the market. While they all fulfill the basic purpose, such as soft starting of the machine and speed or Read more…