When it comes to vegetables, freshness is an essential consideration for consumers. To deliver produce that is as fresh as possible, vegetable processing machines need to stay up and running at all times. For König, a manufacturer of vegetable processing machinery, machine reliability is therefore of utmost importance. The company thus opted for an integrated automation system with protective devices from a single source, including Eaton’s residual-current devices (RCDs), SmartWire-DT, motor starters, soft starters and variable frequency drives.
At the Renner vegetable farm in Fußgönheim, Germany, vegetables such as carrots, spring onions, radishes, turnips and celery are washed, packaged and dispatched to customers already within one hour of being harvested. To clean the fresh produce, Renner relies on six processing machines that wash off soil particles and cut off the roots and any excess leaves. To guarantee the freshness of its vegetables, Renner needs to keep unplanned downtime to an absolute minimum. Any delays could lead to reduced produce quality and lost profit.
König Sondermaschinen, based in Dannstadt-Schauernheim, Germany, manufactures harvesting and vegetable processing equipment that is tailored to the precise needs of agricultural customers like Renner. König’s customers demand processing and packaging equipment that delivers reliable uptime. To meet these needs, König turned to Eaton. In particular, the company was looking for a specialised supplier that would be able to provide high-performance, high-quality machines. Eaton recommended implementing an integrated automation system based on the intelligent SmartWire-DT wiring system, in combination with its motor contactors, soft starters, variable frequency drives and RCDs. Together, these components helped to make König’s machines more intelligent.
“We wanted to design a system in which the blades and brushes could be operated separately, and in which the speed of the brushes could be individually adjustable,” explains Christian Stritzinger, Master Electrician at König. “In addition, we also needed to implement adjustable speed control for the conveyor belt that transports the vegetables through the system.”
The machine that König built for Renner is equipped with four rotating brushes and three blade systems for cutting the roots and leaves to the required lengths. In addition, four pumps control the water pressure, which can be adjusted based on the vegetable type and the amount of soil that needs to be removed.
“As a result, switching the machine on and off requires many components and multiple variable frequency drives”, says Stritzinger. “In order to reduce the amount of wiring in the machine, we decided to use Eaton’s SmartWire-DT system.” Thanks to this intelligent wiring system, the individual switching devices and drives are connected via an eight-pole wiring harness with simple plug-in terminals, rather than implementing the connection to the controller by means of point-to-point wiring. The SmartWire-DT cable supplies the connected devices with electricity and simultaneously communicates all their data. “As a result of implementing SmartWire-DT, we are using approximately 40 % less wiring compared to traditional machines,” says Stritzinger.
Another advantage of this Eaton solution is the data transparency it provides. Information from the connected components can be easily and directly retrieved via SmartWire-DT. For example, König programmed the machine in such a way that it indicates exactly which motor-protective device has tripped in the event of a fault. Operators can then view the associated error message on a multi-function panel, the MFD-Titan from Eaton. In addition to the exact location, SmartWire-DT also transmits the cause of the fault and indicates if a short circuit of overload is present. “The display on the panel eliminates the need for time-consuming troubleshooting. Customers can immediately see which component malfunctioned and why, thereby enabling them to reduce unplanned downtime,” says Stritzinger.
To enable continuous communication, König additionally installed Eaton components to operate the speed-controlled motors of the Renner machine, including five PowerXL DE11 variable frequency drives that are also connected via the SmartWire-DT cable. The drives control the motors of the four brushes as well as the belt drive motor. Variable frequency drives are a new class of device that falls between a frequency inverter and a motor starter. Frequency inverters are often oversized and too complex to operate, while motor starters offer only limited functionality. Variable frequency drives close this gap by combining the advantages of both devices. They enable variable speed control in applications up to 7.5 kW, and thanks to their out-of-the-box functionality they can be installed without any prior configuration, much like a contactor or motor starter.
“Configuring the devices is much simpler than with conventional frequency inverters,” says Stritzinger. “We only had to set the minimum and maximum frequencies as well as the motor run-up and run-down times; all the other parameters were pre-set. What’s more, variable frequency drives are also 10-15 % cheaper.”
And the DE11 offers one more advantage: “It is also possible to manually control the variable frequency drive,” Stritzinger explains. “If the control system should fail, the customer can simply switch on each individual drive manually. This is also important in order to avoid unnecessary downtime.”
In addition to the new variable frequency drives, König also installed motor-protective circuit breakers from Eaton on the drives of the blades and conveyor belts. Eaton components also ensure the reliable operation of the pump system. “We installed soft starters to optimise the process of switching the pumps on and off. This allows us to avoid pressure surges and thereby to extend the service life of the equipment,” says Stritzinger. A total of 56 system components are controlled via two easy800 control relays. According to Stritzinger, “They are considerably easier to program than a PLC with CODESYS, for example.”
Conventional type-A RCDs were installed in the machine to protect operators as well as the system. However, König is already thinking about new ways to further optimise its machines. “Today, we can connect a maximum of three frequency inverters to a standard residual-current circuit breaker,” Stritzinger explains. Anything above that might lead to nuisance tripping.”
As an alternative, Eaton offers G/BFQ-type residual-current circuit breakers, which have been specifically designed for use with frequency inverters. They are considerably less susceptible to system-related leakage currents in the frequency range from 60 Hz to 100 Hz, and thereby deliver enhanced system stability.
König is thus using a variety of methods to reduce unnecessary downtime of its vegetable processing equipment. Eaton’s solutions have made this significantly easier. “With Eaton technology, everything just fits together – the integration of the various components has simplified the development, commissioning and operation of our machines enormously,” Stritzinger emphasises.
The enhanced reliability of the vegetable processing system ensures that customers receive produce that is always fresh and crisp.