Electricity and Control January 2021

DRIVES, MOTORS + SWITCHGEAR

Energy-efficient drives for farmers

In this case study Danfoss South Africa and engineering components provider BMG, an authorised DrivePro ® service partner of Danfoss, share how they assisted a commercial maize farmer in BarklyWest, Northern Cape, with the technology required to overcome challenges the farmer was facing with inadequate electricity supply.

Sydney Govender, Country Sales Manager – Drives, Danfoss South Africa.

T he installation of new electro- mechanical systems supports energy savings, more effective irrigation and, in turn, increased pro- duction capacity. This initiative has since been followed by other commer- cial farmers in the wider area. In recent years, South African energy security has been constrained and while macroeconomic steps are in progress to correct this, the continuing unreliability of the country’s

and this makes effective irrigation essential for successful crop yields. Mick Baugh, Electronics Manager, Electromechanical Division at BMG, explains. “Pumping and irrigation were the largest consumers of power on this maize-producing farm and the farmer was limited by a power supply of only 200 kVA +/- 300 A. Additionally, the farmer wanted to expand his crops to include pecan nuts, but was unable to because of the power supply limitations. The project required that we assist in enabling more efficient use of the limited power supply and reducing the cost of irrigation per hectare.” Inefficiencies in the system - At the outset of the project, one of the pump sets sup- plied five centre pivots and some orchards. - The first pump set consisted of 1 x 37 kW, 1 x 22 kW and 2 x 11 kW pumps. - This equated to an installed power of 81 kW, with an ab- sorbed power of 75 kW, which meant the pump set was drawing a current of +/- 150 A. - Additionally, the pumps were started by star/delta start- ers, and the only form of flow control was provided by valves. The solution The use of ac variable speed drives (VSDs) on all pump sets provided the solution. Danfoss VLT ® AQUA Drive FC 202 Variable Speed Drives, which offer additional energy savings compared with most traditional variable speed drive controls, are de- signed for water and wastewater applications, including irrigation. These VSDs were fitted to all pumps in the in- stallation and are controlled by pressure transducers set to match the varying demands of different irrigation require- ments. The only peripheral component required was the pressure transducer. Pump controllers and valves were not needed for flow-control in this system. Baugh adds, “There were a number of reasons why BMG chose these Danfoss VSDs. For example, a key feature of

Mick Baugh, Electronics Manager, Electromechanical Division, BMG.

electricity supply and escalating costs can affect farming in several ways, impacting on operations planning, spoiling of produce and disrupted irrigation schedules.

Furthermore, the Development Bank of Southern Africa recognises South Africa as a water-scarce country, which makes operational and energy efficiencies all the more important in assisting with effective irrigation (i) . The challenge For the maize farmer in Barkly West dealing with an inadequate electricity supply, the challenge was to free up existing electricity supply by improving usage efficiencies. Sydney Govender, Danfoss Country Sales Manager – Drives SSA, says, “Through the Danfoss-BMG collaboration we assisted the farmer in tackling this challenge.” He highlights that the region in which the farm is located receives little rainfall throughout the year

Danfoss VLT ® AQUA Drive FC 202 Variable Speed Drives were fitted to all pumps in the installation.

14 Electricity + Control JANUARY 2021