Agriculture is the largest branch of the economy and an important source of income in many parts of Africa. As a result of climate change, however, many regions are experiencing more irregular and ever decreasing rainfall. One dairy farm in South Africa needed 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, which specialises in agricultural operations, for example in areas such as irrigation, refrigeration, feed processing and solar power generation.

Low-resource irrigation system using gravity
The planned irrigation system was to comprise two reservoirs at different heights, which would be filled with water by a total of six underground well pumps overnight, when the energy costs were low. A transport pump is used to transfer water from the lower reservoir to the higher one. The height difference allows the sprinkler system to be operated using gravity alone during the day, making it particularly efficient. The farm animals and the dairy can also take their water supply from this irrigation system. The key requirements of the project were cost efficiency and low energy consumption, and it also needed to be very reliable and easy to maintain.
Following an in-depth planning and consultation process, Pienaar Elektries opted for a number of automation products from Delta, attracted by the diverse portfolio of powerful yet economic solutions.

User-friendly thanks to automation
Five low-energy Delta CP2000 frequency drives drive the six underground well pumps and ensure that the water brought to the surface is transferred on to the higher tank. The CP models feature a PID controller with feedback that 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 control switches to the next the borehole and prevents the pumps from being damaged. The system has various Delta DVP series programmable logic controllers (PLCs): three DVP04AD PLCs monitor the sensors in boreholes and keep the water level above the predetermined value. Five DVP16SP PLCs regulate the motors. One DVP12SE PLC monitors the water level in the top reservoir and the animal watering stations, while a further DVP controller manages the sprinkler installation. Two human-machine interfaces (HMI) from the DOP-100 series are used to display all of the processes in the system and show system information and warning indicators on a 7 or 15-inch touch screen.   A multilingual input function means that Delta’s HMIs are the best solution for any location. In-house software also allows the time configuration and energy costs to be monitored remotely. Users can also monitor the entire process via the DOP-100 VNC server.

Precisely tailored pump action for efficient energy and water usage
The team from Pienaar Elektries values Delta as a flexible partner that offers good service and a range of powerful automation solutions that are easy to integrate. “In this project it was important to tailor the action of the individual pumps to each other, to optimise the available water, and avoid damaging the pumps,” explained Martien Heesterbeek, Delta Product Manager. “Our DVP series PLCs are ideal for this since they ensure very fast communication with the CP motor drives and allow the irrigation system to be controlled reliably.”
The system is working without any issues and supplies both livestock and crops with sufficient water, even during periods of low rainfall. “We are very happy with the efficient energy consumption of the low-cost pump and water storage solution,” said Paul Pienaar, owner of Pienaar Elektries. “The HMI allows us to configure the system to only pump water up at night, keeping the energy costs low. Simple maintenance, monitoring and remote troubleshooting save us lots of time and effort.”