Electricity and Control May 2022

DRIVES, MOTORS + SWITCHGEAR

Resource-efficient irrigation Agriculture is an important growth sector and a key contributor to the South African economy, as it is for many other African countries. As a result of climate change, however, various regions are experiencing increasingly irregular rainfall and at decreasing levels.The owner of a dairy farm in South Africa was looking to establish a pump system to access ground water from wells and ensure a reliable and cost-effective water supply.The farm’s owner commissioned the implementation of a suitable system from a family firm of electrical installation planners, Pienaar Elektries.

P ienaar Elektries specialises in agricultural opera tions, in areas such as irrigation, refrigeration, feed processing and solar power generation, among oth ers. The planned irrigation system was to comprise two reservoirs at different heights. These were to be filled with water overnight, when energy costs are comparatively low, by a total of six underground well pumps. A transport pump is used to transfer water from the lower reservoir to the high er one. The height difference allows the sprinkler system to be operated using gravity alone during the day, making it particularly efficient. The same water supply system also provides drinking water for the farm animals and serves the dairy. Key requirements of the project were cost efficiency and low energy consumption, and it needed to be reliable and easy to maintain. Following a thorough planning and consultation pro cess, Pienaar Elektries opted for a number of automation products from Delta, working with the diverse portfolio of powerful yet economic solutions. User-friendly automation Five low-energy Delta CP2000 frequency drives drive the six underground well pumps and ensure the water brought to the surface is transferred on to the higher tank. The CP models feature a PID controller (a proportional-integral derivative controller) with feedback, which allows the water level in the tanks and boreholes to be monitored and corrected. This is done by alternating between the different pumps and continually monitoring the flow: if the borehole level falls below a minimum predetermined by the user, the PLC switches to the next borehole and prevents the pumps from being damaged. The system makes use of various Delta DVP series pro grammable logic controllers (PLCs): three DVP04AD PLCs monitor the sensors in the boreholes and keep the water lev el above the predetermined minimum value. Five DVP16SP PLCs regulate the motors. One DVP12SE PLC monitors the water level in the top reservoir and the animal watering sta tions, and a further DVP controller manages the sprinkler installation. Two human-machine interfaces (HMIs) from the DOP-100 series are used to display all the processes in the system and show system information and warning indicators on a 7- or 15-inch touch screen. In-house soft ware allows the time configuration and energy costs to be

The control system provides for an efficient water pumping and irrigation system.

monitored remotely. Users can also monitor the entire process via the DOP-100 virtual network computing (VNC) server. Efficient energy and water usage The team from Pienaar Elektries values Delta as a flexible part ner that offers good service and a range of automation solutions that are easy to integrate. “In this project it was important to tailor

A selection of Delta’s automation solutions – including drives, PLCs and HMIs – were used in this project.

the action of the individual pumps to each other, to manage use of the available water optimally and avoid damaging the pumps,” explained Martien Heesterbeek, Delta Product Manager. “Our DVP series PLCs are ideal for this as they ensure fast communication with the CP motor drives and allow for the irrigation system to be controlled reliably.” The system is working well and supplies livestock and crops with sufficient water, even during periods of low rain fall. Paul Pienaar, owner of Pienaar Elektries said, “We are very happy with the efficient energy consumption of the low-cost pump and water storage solution. The HMI allows us to configure the system to pump water up only at night, keeping the energy costs low. Simple maintenance, moni toring and remote troubleshooting save us a lot of time and effort.” □

For more information visit: www.delta.com

MAY 2022 Electricity + Control

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