The illustration below shows a Stopping Category 0 (EN 60204-1) with safety Category 3 (EN 954-1). The circuit interrupt is caused by an opening door
contact. The illustration also shows how to connect a non-safety related hardware coast.
Illustration 2.3: Illustration of the essential aspects of an installation to achieve a Stopping Category 0 (EN 60204-1) with safety Category
3 (EN 954-1).
2.7 Advantages
2.7.1 Why use a Frequency Converter for Controlling Fans and Pumps?
A frequency converter takes advantage of the fact that centrifugal fans and pumps follow the laws of proportionality for such fans and pumps. For further
information see the text
The Laws of Proportionality, page 19
.
2.7.2 The Clear Advantage - Energy Savings
The very clear advantage of using a frequency converter for controlling the speed of fans or pumps lies in the electricity savings.
When comparing with alternative control systems and technologies, a frequency converter is the optimum energy control system for controlling fan and
pump systems.
Illustration 2.4: The graph is showing fan curves (A, B and
C) for reduced fan volumes.
VLT
®
HVAC Drive Design Guide
2 Introduction to VLT HVAC Drive
MG.11.B9.02 - VLT
®
is a registered Danfoss trademark
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