Variable Frequency Drives for conveyor starting
By K Moss, Zest WEG Group
Electricity+Control, May 2014 (pages 26-29)
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Increasingly, the advantages of using variable frequency drives (VFDs) are expanding their use for conveyor starting, not only in applications that require speed control but also in applications that require torque control and mechanical ‘soft starting’. Conveyor belt application for conveyor starting is one such example.
Ultimately the conveyor belt starting system required for a given conveyor application needs to be defined by the conveyor designer taking many variables into consideration, such as variable speed versus fixed speed, conveyor geometry, whether regenerative braking is required or not, load sharing requirements, and many other factors. The decision can then be based on the system that provides the best balance of performance under all belt conditions, cost optimisation (including capital cost and energy cost) and reliability.
The main challenge for the designer, is that the conveyor starting system must produce enough torque to get the belt load away, while at the same time applying this torque in a smooth and controlled manner to limit the negative mechanical effects of high impact acceleration. Protection against a belt jam is also important so this torque needs to be limited in case of a failure.
- The advantages of using Variable Frequency Drives are expanding their use as the starter of choice.
- The conveyor starting system required for a given conveyor application needs to be defined by the conveyor designer – taking many variables into consideration.
- Variable Frequency Drives offer a complete conveyor starting system protection means against overload, over-voltage, under-voltage, short circuit and have the ability to ride through voltage dips.