Electricity and Control January 2021

DRIVES, MOTORS + SWITCHGEAR

At a glance 

References (i) https://www.dbsa.org/EN/About-Us/Publications/Documents/DPD%20 No12.%20Water%20security%20in%20South%20Africa.pdf Bearing Man Group (Pty) Ltd (BMG) supplies engineering products and services to the industrial, manufacturing, mining and agricultural sectors through more than 100 branches in 15 countries across sub-Saharan Africa. BMG’s established support divisions include technical resources, field services, predictive maintenance, technical and commercial training, supply contract management, and project engineering. Danfoss Drives, a member of the Danfoss group, is a world leader in variable speed control of electric motors. Since 1968, the company has been a pioneer in ac drives. Its VACON ® drives form the foundation for optimisation in industrial applications. VLT ® drives play a key role at the sharp end of global resource manage- ment and factory automation. Danfoss ac drives adapt to any mo- tor technology and serve in the power range 0.18 kW to 6.0 MW. throughout Southern Africa with the selection, installation and operation of new electromechanical systems. These projects are designed to improve efficiencies, reduce energy consumption and minimise maintenance require- ments,” Baugh adds. Govender notes, “Maize is South Africa’s most important field crop, being a staple food for many people in the country and making a significant contribution to the economy. It is also an export product, although maize exports tend to be inconsistent as surplus levels vary from one year to the next.” He adds, “This Danfoss-BMG collaboration, and other projects like it, illustrate how we can assist farmers to free up energy supply, which can then be channelled elsewhere to increase productivity. If the farming sector were to follow this example more widely, it would assist individual farmers and enable them to play their own incremental role in improving the macroeconomics of the country, particularly while the electricity supply remains constrained.” □ The maize farmer in BarklyWest was dealing with a limited and inadequate electricity supply and pumping and irrigation were the largest consumers of power on the farm.  The challenge was to free up existing electricity supply by improving usage efficiencies.  The switch to ac variable speed drives on all pump sets provided an energy-saving solution as well as other benefits.

The new electromechanical systems installed improve energy efficiency and reduce energy and maintenance costs, supporting more effective irrigation and higher crop yields. the Danfoss VLT ® AQUA Drive FC 202 VSDs is the inclusion of a soft start/stop facility, which prevents water hammer on starting and stopping the pumps, reducing the possibility of burst pipes. Wear and tear on couplings, pumps and pipes is also reduced. These variable speed drives are available from BMG in IP55 enclosures, which do not require dedicated panels for mounting and this eliminates the need for additional cooling and ventilation measures normally required to extract heat during operation. Furthermore, closed loop controllers mean the only piece of peripheral equipment required is a pressure transducer – no pump controller is needed. “In addition, BMG, as an authorised Danfoss service partner with accredited technical staff and an extensive spares stock holding, can offer farmers support all year round. With regard to DrivePro services, we stock a number of service exchange units and spare parts at the nearest BMG branch in Kimberley.” The results After the installation of the VSDs and programming the set point to 2.8 bar, the Danfoss-BMG team was able to run the same pump set with an absorbed power of 51 kW, a saving of 24 kW or 50 A. At the start of the changeover, the farmer went with a set of three variable speed drives on three pumps and, because of the energy saving achieved, he subsequently installed VSDs on every pump on the farm. “At the last count,” says Baugh, “there were over 20 VSDs on the farm, with a projected annual power saving of 155 491 kW. Following the installation of variable speed drives on all pump sets, the power supply is used more efficiently, providing for improved crop production and allowing for the farmer to extend his crops to include pecan nuts. “The project was conducted under the umbrella of BMG’s Boer Slim/Smart Farming initiative, which has been operating for some six years now, to assist farmers

For more information visit: http://drives.danfoss.com or: www.bmgworld.net

Electricity + Control JANUARY 2021

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