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 is whether a tap changer is needed or not. The Read more…
Part 2: Overview of motor starting methods Electric motors as work horses of the industry are extensively used since decades. The topic of motor starting is therefore well known and various starting methods had been developed. This article presents an overview of most common motor starting methods. Which solution to Read more…
Part 1: Direct on-line start This series talks about solutions to start larger medium voltage motors. Aspects such as effectiveness, cost, impact on the supplying grid and driven load or effects on the motor design are taken into account. Article at hand describes the simplest solution: motor direct on-line start. Read more…
Transformer short circuit impedance Short-circuit impedance of a transformer, impedance voltage or just impedance are terms often used as synonyms. They describe one of the most important transformer parameter: short-circuit impedance. This article, as part of our VFD transformers series [1], presents the short-circuit impedance from VFD design perspective. After Read more…