Converter duty transformers / rectifier duty transformers / VFD transformers – these are all synonyms for transformer supplying power electronic based converters. What is so special about these animals? How do they differ from a normal distribution or power transformer? How to protect these transformers and maximize their reliability?
How to consider explosion load of a transformer? Abstract When oil filled transformer is installed indoors, the explosion load becomes relevant for the building design. Introduction In a common setup, dry type transformers are installed indoors while oil-filled transformers stand outdoors. Dry transformer can be located outdoors as well if Read more
309 days in Spain, over 1 year in Sweden No, this is not a post about my sabbatical. It is about two success stories of our rental transformer service. In critical situations, when original drive transformer is unavailable, our solution helps to keep the production up. What is our capital Read more
Temperature rise test of converter transformers Abstract Purpose of a temperature rise test is to verify the thermal design of a transformer. The injected losses shall correspond to the losses in real operation at rated load. Converter transformers are subjected to harmonics. Those harmonics contribute to the overall losses and Read more
How to interpret dual rating transformers? You might have seen transformer data with two different values of apparent power, such as e.g. 20/25 MVA or 75/100 MVA. What does it mean and how to deal with dual rating transformers? Transformer rated power A transformer is characterized by its nominal output Read more
What has a transformer and a gear in common? Transformer and gearbox are two quite different devices. Nevertheless, they have something in common. The analogy described in this article may help to understand how a drive system is dimensioned and configured, what limitations the designer faces and finally how do Read more
Neutral point treatment of a converter transformer A common question of system integrators or end users is about the neutral point treatment of a converter transformer. Can or shall the neutral point be earthed? What are the consequences for the system design and performance of a drive system? How does Read more
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 of short-circuit impedance. Definition 1 Short-circuit impedance (reactance and resistance) 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 of VFD power cells). Such multi-winding transformer represents a challenge Read more
Can 50 Hz rated equipment operate on 60 Hz grid and vice versa? Globalization affects various areas of our lives. Variable speed drive systems are no exception. It happens that components manufactured in a “50 Hz country” will be used in a “60 Hz country” or the other way round. Read more
What is a Phase-Shifting Transformer? VFD multi-winding transformers typically use phase-shifting feature in order to eliminate (cancel) certain harmonic orders in the spectrum of the current drawn from the grid. There are, however, other transformers that also use phase-shifting, but it a completely different power range and application. This blog Read more