Specialist variable speed drive system used in test rig upgrade

Tasked with designing and supplying the control system for a complex pump test rig, System Control Solutions, a specialist in automation and variable speed drive applications, faced an interesting challenge. The rig had to be suitable for use with pumps having to drive motors ranging from just a few kilowatts up to more than 300kW, and it had to be capable of testing all sizes over a wide range of operating speeds. The company quickly discovered, however, that using a Vacon NXP variable speed drive would allow this challenge to be addressed efficiently and economically.

Amarinth a UK manufacturer of standard and custom-designed centrifugal process pumps for use in demanding applications. In order to ensure that its products always meet the required standards of performance and reliability, Amarinth carries out extensive in-house testing of its products before despatch. Recently, the company decided to upgrade its test facilities with a new test rig capable of providing detailed performance information for electrically driven pumps of all sizes.

To achieve this, it was necessary for the rig to accurately control the speed of the pump under test, and to make provision for this speed to be varied over a wide range. This would, for example, allow acquisition of the data needed for plotting flow/speed curves, and for calculating the pump's energy efficiency under various operating conditions.

To supply the control system for the test rig, Amarinth approached System Control Solutions, a company with experience in the design of used in s for specialised applications. On looking at the requirements for this project, the engineers at System Control Solutions realised that designing a system that would achieve the required performance with a single size of motor, or with a small range of motor sizes, would be straightforward. Designing a system to work with motors anywhere between a few kilowatts and 300kW was a considerably greater challenge.

An application software library of special functions

The engineers knew, however, that a feature of Vacon drives is their versatility. Vacon achieves this by adopting a somewhat different approach from its competitors to adding functionality. Instead of trying to cram every function that might possibly be required into the standard software supplied with every drive, Vacon offers an application software library of special functions that can readily be installed, as required, to supplement the company's standard software. This allows Vacon to offer an almost unlimited range of functions for special applications without making its standard firmware so complex that the drives become difficult to set up and use.

After discussing the specific requirements of the Amarinth application with Vacon, the engineers from System Control Solutions found that a software package was indeed available to meet their needs. Vacon Multi Motor software allows drives to store multiple parameter sets, with the parameter set required in any particular instance selectable via the drive's digital inputs.

For the Amarinth pump test rig, a Vacon NXP series drive rated at 315kW was selected. After installation of the Multi Motor software, this was programmed with eight different parameter sets, enabling this one drive to "impersonate' drives rated at 10kW, 50kW, 100kW and any one of another five ratings up the maximum of 315kW. The operator of the test rig selects the parameter set required to test a particular pump simply by pressing a pushbutton.

Bob Halls, UK Technical Sales Manager at System Control Solutions, says: "With the Vacon Multi Motor software, this arrangement was very easy to implement, and it worked exactly as expected right from the word go. The drive system does precisely what Amarinth wants, it does it reliably and it does it without unnecessary complexity. This was an ideal solution to an interesting problem."

Vacon NXP drives of the type used in the Amarinth test rig provide excellent dynamic performance and speed holding, coupled with wide compatibility with different types of motor, all characteristics that were of particular importance in this application. The drives also have excellent EMC performance, and combine the use of premium grade components with advanced thermal handling to ensure long reliable working lives.

Visit the website at www.vacon.com to find out more about the Vacon NXP variable speed drive and application software library.