Compact motor controllers save energy

Paul Boughton
Digistart, Leroy-Somer's new electronic controller for induction motors, integrates the latest technological changes including an optimised bypass function. It is available in two ranges adapted to market requirements: the D2 range of compact starters is rated from 18-200A; the D3 range of advanced controllers is rated from 23-1600A.
The use of the bypass offers significant savings: a four per cent reduction in consumption at steady state, plus there is no need for forced ventilation, and smaller units can be specified - which enables cabinet space to be saved.
Digistart's operating principle is as follows: the power electronics perform start-up and thus limit the current draw of the induction motor; then it is shunted at the end of the starting phase by the internal bypass. Note also the control electronics protect and control the motor up to the stopping phase.
This arrangement also enables additional savings to be made on the external contact and its implementation. The Digistart's compact dimensions also reduce the overall installation weight and volume. Leroy-Somer says that Digistart units are useful for upgrading existing installations, enabling the linking of delta connection motors - which replaces star/delta starters - and uses the six motor power supply cables. Additionally, this enables a saving of at least one rating size in controller dimensioning.
The intuitive Digistart navigator enables simple adjustment of the current ranges or limitations. Operators have immediate access to preset configurations for common applications such as pumping, ventilation and conveying.
Digistart also facilitates remote monitoring by enabling users to access the log of failsafe actuation operations, events, consumption and operating conditions, as well as providing traceability of parameter changes. It can also simulate operation by forcing the control-command, enables users to view the input/output state, and reports can be provided on operating time, number of start-ups and other aspects of the unit's operation.
Digistart units can operate with 200-440V, 200-575V or 690V three-phase networks. They can also control several induction motors coupled in parallel as well as a collector ring motor. Available on D3 (ratings 360-1600A), the power inputs and outputs may be installed on request above and/or under the starter, according to the layout of cables in the cabinet. The Choice of fieldbus modules is: Modbus RTU, USB, Devicenet and Profibus.
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