The Control Techniques Drives and Controls Handbook
This handbook contains technical information for practicing drive and electrical engineers, covering the technology underlying drives, motors, and control units and modern practical applications.
TABLE OF CONTENTS The Control Techniques Drives and Controls Handbook
3: APPLICATION PRINCIPLES/EXAMPLES
3 APPLICATION PRINCIPLES/EXAMPLES
The applications in which variable-speed drives are applied are many and extremely varied. The reasons for using variable-speed drives are almost as diverse. This section brings together a broad cross section of applications. In some cases technical details behind the application of the drives are given; in others emphasis is given to the benefits that variable-speed drives offer from the user's perspective. In many cases it can be seen that not only is the core performance of the drive critical, but also the auxiliary features. The capability and flexibility of the soft logic programmable applications module features heavily in many of the application examples.
CRANES AND HOISTS
General
The use of variable-speed drives on cranes and hoists is very widespread. Historically the characteristics of slip-ring induction motors with resistance and later phase control in the rotor circuit were very popular. Today the use of A.C. cage induction motors predominates, with closed-loop flux-vector control used for precise control, and where performance is not important open-loop control is applied.
There is a substantial market for retrofitting of the drives systems on cranes since the electrical systems invariably have a shorter life span than the very substantial mechanical parts. There comes a point where drives maintenance on cranes becomes uneconomic and downtime is seriously affecting the operation of the factory or dockyard.
Planning an Installation
In most retrofit applications with state-of-the-art inverter control systems, there are several issues:
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the need to install the equipment in the existing environment
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the need...
Copyright The Institution of Electrical Engineers 2001 under license agreement with Books24x7
