1 The Decentral Concept
1.1 Introduction
Danfoss was the world's first company to manufacture and supply frequency converters for infinitely variable speed control of three-phase AC motors.
Until then, AC motors had to operate at the speed determined by the frequency of the main power supply.
Production of frequency converters started in 1968. The first frequency converter was also the first decentralised drive as it was placed next to the motor.
The first frequency converter was totally enclosed and filled with silicone oil for cooling, as semiconductors of that time were very inefficient. The enclosure
design was made for mounting the drive directly in the application next to the motor. Temperature, water, cleaning agents, dust and other environmental
factors were also no problem, even in harsh environments.
Semiconductors improved during the next decades. Air-cooling showed sufficient and oil cooling was abandoned. At the same time use of frequency
converters grew significantly. PLCs gained a footing for advanced application control and it became common practice to install all frequency converters
in one cabinet, rather than several places in the factory.
Continuing improvements in semi-conductors and related technologies - such as fieldbus technology - now again makes it feasible to consider installing
drives close to the motors, achieving the benefits of decentralised installation without the disadvantages from the first oil-filled frequency converters.
Development of automation in industry is based on the ability to send and receive data from the application needed to control the processes. More and
more sensors are installed and more and more data is submitted to the central PLC control. This trend depends on increased use of fieldbus systems.
Industrial sources often claim that up to 30 % of all drive installations will be installed decentrally within the next few years and the trend towards
distributed intelligent control is undisputed as more and more components and applications are developed for decentralised installation.
This book is a general introduction to basic features of decentralised installation philosophies for motor controls and differences from the centralised
concept. It will help you choose the most suitable concept and guide you through the process of selecting the appropriate products.
Finally we have included comprehensive information about the Danfoss decentralised products.
VLT
®
Decentral FCD 300 Design Guide
1 The Decentral Concept
MG.90.S1.02 - VLT
®
is a registered Danfoss trademark
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