Input power factor and reactive power consumption The focus in all energy efficiency initiatives is to minimize the losses, improve the system efficiency and reduce overall power consumption. With “power” people usually refer to active power and this is basically correct. Main purpose of VFD is to reduce active power. Read more
Derating and uprating factors What is the power rating of the specific VFD? An indicative value is provided in the technical catalog or brochure. This value shall refer to certain operation conditions, among others the temperature of cooling medium (air or liquid), content of anti-freeze additive (usually some type of Read more
How to choose a medium voltage VFD:Life cycle cost What is life cycle cost (LCC)? The definition from business dictionary (www.businessdictionary.com) says: Sum of all recurring and one-time (non-recurring) costs over the full life span or a specified period of a good, service, structure, or system. In includes purchase price, Read more
How to choose a medium voltage VFD:Engineering support Engineering support from VFD manufacturer significantly influences how smooth the execution of your project goes and how successful it will be in the end. It also directly impacts the quality of the system solution. Some manufacturers focus on selling their standard ‘catalog Read more
How to choose a medium voltage VFD:Protection concept A variable speed drive system with gaps in protection philosophy is a ticking bomb. It might have a huge impact on plant availability and potentially also on personal safety. Therefore, no compromises shall be accepted. Other topics in this series are definitely Read more
How to choose a medium voltage VFD:Design robustness Every end user probably wishes that his VFD has a robust design and works as intended during the entire lifetime of at least 20 years. Unplanned shutdowns and outages are unwanted. But what is robust design and how can it be achieved? Read more
How to choose a medium voltage VFD:Motor compatibility VFD – motor compatibility is an essential precondition for successful operation of power drive system. There is a large amount of publications underlying this topic. This article aims to explain the matter without requiring the reader to have expert knowledge in this Read more
How to choose a medium voltage VFD: Application requirements The requirements of your application are key when selecting suitable VFD. If you check the websites of leading medium voltage VFD manufacturers you will find several products with different performance data. Why? Several topologies are available on the market and each Read more
How to choose a medium voltage VFD (Part 1: Introduction) We start a new series dedicated to the selection of medium voltage variable frequency drive. Some points might also be valid for low voltage VFDs. However, many topics require different considerations in medium voltage range compared to low voltage. Purchasing Read more
Reliability and availability (Part 4: IGCT based converters) IGCT is a power semiconductor used in medium voltage converter applications. The abbreviation stands for Integrated gate-commutated thyristor. Unlike classical thyristor that can only be switched on, IGCT can be switched on and off through its adjacent gate unit. Therefore, it is Read more