Enkeldebosch unearths productivity with new super line

Schneider Electric along with an alliance partner Vennic has rooted a complete integrated solution at Enkeldebosch Boerdery’s potato grading, sorting and bagging (PGSB) plant.The Mpumalanga based farm owner, Christo Kruger, approached Vennic to enhance his PGSB plant from 28 electric motors to 122. The plant is divided into five different segments:
Bulk hopper – where the potatoes are dumped into the machine.
Seed line – where the seed for the next season is sorted and packed.
Wash line – where the potatoes are washed.
Sorting line – where the potatoes are sorted, the good from the bad and the large from the small.
Packing line – where the potatoes are stored, conveyed, weighed and packed.
Says Pierre Venter, head of the electrical department at Vennic: “Due to the sheer size of Enkeldebosch’s PGSB plant, Vennic chose a SCADA system with a user-friendly interface and a touchscreen HMI that is straightforward to use. Of note is that before we could get to the testing and commissioning phase, we had to complete the entire installation, resulting in us installing cable to all motors. That’s almost eight kilometres of cable onto 150 metres of cable trays using over 10,000 cable ties.”
Venter furthermore explains that each line now has its own start/stop command and will not start if its upstream line is not started. Also, if an upstream line is stopped, all downstream lines will stop. If a line is started, the motors on that line will start in one-second intervals to prevent both a very high startup current and a maximum demand peak, ensuring that
the startup load on the generator is less in the case of an Eskom supply failure. Also, if a motor in the middle of a line has not started, the starting sequence will not continue. Venter explains: “The downstream trip fallout was of cardinal importance as a failure could cause a potato pile up and eventually machine damage.”
At the bulk hopper, Vennic deployed a Schneider Electric high frequency ultra-sonic sensor to measure the inflow of potatoes. If there are no potatoes at the inflow point, the variable speed drive (VSD) on the bulk hopper motor will speed up to the maximum set speed, bringing the potatoes to the inflow point faster than it ever did before, thereby saving the farm a lot of time. Once at the inflow point, the ultra-sonic will measure the height of the pile of potatoes and the motor speed will, accordingly, slow down to prevent a potato overflow.
In the drying tunnel at the beginning of the sorting line, a gas burner is used to heat the tunnel to an adjustable set point to dry the potatoes. Real time temperature value is also displayed.
On the other end of the PGSB plant, the packing segment, there are nine large storage hoppers in which the different sizes and grades of potatoes are stored. Each of these hoppers can be selected individually to pull the desired size and grade of potatoes out of the hopper onto the main distribution conveyor in the packing segment. Each hopper now has its own VSD and the speed can be adjusted from one percent to 100 percent. Here, the potatoes are also weighed, bagged and packed on two lines, either with a Sennah semi-automatic bagging machines or with a fully automatic Propack bagging machine.
“Owing to the fact that the Propack is upstream to the hoppers, Vennic had to interlock the VSDs with the Propack to once again prevent a pile up of potatoes – should the Propack stop bagging the potatoes being fed to it from the storage hoppers. The plant now has the capability to bag and pack 1,800 bags of potatoes in a single hour,” says Venter.
The upgrade is made possible with two M340 PLC racks linked to a total of 320 digital inputs, 160 digital outputs, eight analogue inputs and 32 analogue outputs. There is spare I/O that is reserved for future use. In addition, a Modbus network is utilised to acquire data from all 10 VSDs and a power meter – all displayed on the SCADA.
Venter elaborates: “Interfacing was done by a 5.7inch touchscreen HMI mounted on the MCC, which reflects, via a
Wi-Fi network, onto the client’s iPad using Vijeo Design Air, allowing the user to use and change all the states and parameters of the PGSB plant. By logging into the maintenance function all the conveyors and fans can be started individually, out of sequence, independently from one another while doing maintenance.”
Also displayed on the SCADA is a complete layout of the MCC, with all its 122 starters, making fault finding quick and easy, as well as locating a tripped motor.
Vennic employees accomplished this entire project – from building the panel and the fitting and wiring of all components, to the installation of the panel with all cables reaching the motors and process points, as well as commissioning.
“At the beginning of this entire project, I was skeptical on whether I had made the right decision. But after seeing
the 32 inch SCADA screen, and Vennic introducing me to the wireless iPad control, I knew it was the right decision:
both doing the upgrade and choosing Vennic for their innovative electrical solutions,” concludes Kruger.
Schneider Electric: Tel +27 11 254 6400; ntombi.mhangwani@schneider-electric.com; www.schneider-electric.com
Vennic: Tel +27 15 293 0547; pj@vennic.co.za; www.vennic.co.za