What is the definition of short-circuit impedance? Short-circuit impedance, also called impedance voltage, is an important design parameter of a transformer [1]. Thus, it is crucial to understand this parameter. In this brief post we introduce three ways of definition Read more…
Black Friday Sale MB Drive Services participate in the biggest savings event of the year! The traditional Black Friday sale is combined with a 6 years anniversary of our first blog post that started the whole journey. This Black Friday, Read more…
Considerations about motor noise level This post provides few considerations about motor noise level with respect to inverter supply. Noise might be considered as one performance criteria of the motor. Noise level of electric equipment is regulated by standards and Read more…
Comparison of air core and iron core choke There are various reasons for installation a choke¹ within a variable frequency drive system – see [1] for an overview. The next question is about the design of such choke. This post Read more…
VFD compliance with voltage and current harmonic limits National and international standards provide guidelines and limits for individual harmonics and total harmonic distortion. But how to assess the situation when the VFD meets the limits for voltage harmonics while current Read more…
When to go for an active front end drive? Abstract Grid side of the VFD can be either Diode Front End (DFE) or Active Front End (AFE). The later one is more expensive but brings several additional options such as Read more…
Ratio between grid short-circuit power and VFD installed power Successful integration of a variable frequency drive (VFD) into the electric grid shall follow certain rules. Moreover, the VFD shall comply with standards related to power quality and harmonics. In case Read more…
VFD layout options Introduction Default VFD layout is normally a straight lineup. The individual cabinets are installed side by side on a common base frame. However, specific site restrictions may require adaptations of the mechanical layout in order to fit Read more…
What is the time constant of a dc link? Introduction Most commercially used variable frequency drives (VFD) belong to the category of indirect frequency converters. The AC power of a fix frequency (usually 50 or 60 Hz) is first rectified Read more…
Fault current considerations for integrated transformer of CHB drive Introduction Cascaded H-bridge (CHB) variable frequency drives (VFD) have the input transformer as an integral part of the VFD. This transformer has high number of secondary windings (equal to the number Read more…