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Introduction
Danfoss was the world's first company to manufacture
and supply variable frequency drives 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 electrical power supply.
Production of variable frequency drives started in 1968.
The first variable frequency drive was also the first
decentralized drive as it was placed next to the motor.
The first variable frequency drive 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 variable frequency
drives grew significantly. PLCs gained a footing for
advanced application control and it became common
practice to install all variable frequency drives 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
decentralized installation without the disadvantages
from the first oil-filled variable frequency drives.
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 decentralized installation.
This book is a general introduction to basic features
of decentralized installation philosophies for motor
controls and differences from the centralized
concept. It will help you choose the most suitable
MG.90.F2.22 - VLT is a registered Danfoss trademark
Decentral Solutions
concept and guide you through the process of
selecting the appropriate products.
Finally we have included comprehensive information
about the Danfoss decentralized products.
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