Holmer Maschinenbau GmbH is the global market leader in self-propelled sugar beet harvesters and with its various representative offices, the company is represented worldwide in all sugar beet growing regions. Würth Elektronik ICS developed a central electrical unit that sets new standards in terms of function and clarity for the Terra Felis 3, the most modern beet cleaner loader in the world.

More compact and easier to maintain

Holmer’s requirements for the power distribution solution in the Terra Felis 3 were clearly centered around the customer. The solution needed to be pragmatic and long-lasting, offer modern, yet simple options for (error) diagnostics, and be as lightweight and compact as possible. The central electrical unit developed by Würth Elektronik ICS fulfilled these requirements, replacing the two considerably large, hand-wired switch cabinets that had previously been in use. Completely new reserves in terms of the minimal installation space and more flexibility for future adaptation and expansion options also resulted due to the space saved. Würth Elektronik ICS has already successfully implemented several power distribution and control solutions for Holmer vehicles in recent years. Therefore, it was commissioned with developing a central electrical unit for the Terra Felis 3.

The first ideas for the so far fifth joint project were routinely exchanged by phone and, as in previous years, the project started with a kick-off meeting at Holmer in Schierling, Germany. Siegfried Hort, responsible for machine electronics at Holmer, presented the planned machine electronics concept including the circuit diagram, and additionally explained the mechanical details and installation requirements directly at the machine. The concept including technical specifications and quotation was developed for the new central electrical unit based on the machine circuit diagram in only four weeks.

As an experienced development partner in the field of mobile machines and commercial vehicles, Würth Elektronik ICS designed a solution that meets the typical requirements in this area such as shock, vibration, temperature, and current carrying capacity and maps the complex interrelationships of the many consumers on the circuit board.

The following tasks are performed by the central electrical unit:

• Complete signal distribution
• Power/relay circuitry
• Machine function safeguards
• Complete load distribution
• Turn signal control system
• Follow-up control via multifunction time relay
• Acoustic function signaling via a buzzer

In addition, the central electrical unit in the vehicle serves as an interface to control units, supplies power for lighting functions, and provides diagnostic data via D-sub connectors.

Every Gram Counts

The advantages of the new central electrical unit are that it is more compact and clearer, easier to install, quicker to operate, and easier to maintain. “Of utmost importance, however, is that it saves cables and reduces weight - and thus saves raw materials (e.g. copper) and energy -,” explains Siegfried Hort. The ground – and soil – is the basis of all agricultural production and the customer’s capital. This makes it all the more important to maintain the soil structure – and soil protection begins with weight. It is not without reason that lightweight construction is a central aspect of Holmer’s vehicle concepts, and it is systematically implemented in all vehicles. This in turn is impressively demonstrated by the Holmer sugar beet harvesters: they are three tons lighter than other harvesters on the market. With over 35,000 components, every gram that can be saved counts. The significantly lower weight served as strong argument in favor of the new central electrical unit from Würth Elektronik ICS.

Even More Reliability

The special feature of the solutions developed by Würth Elektronik ICS is that the power distribution and fuse protection as well as all possible bus functions are compactly combined on one PCB. The central electrical unit developed for Holmer also stands out with its high reliability and simplified troubleshooting. “You start to worry that you’ll be out of work sometime,” comments an electrician in production at Holmer. And in truth, contact problems at the connectors, like incorrectly plugging relays and fuses, have become a thing of the past. The central electrical unit is subjected to a 100 percent short-circuit and connection test and mounted before delivery, which means that it is directly prepared in Holmer’s production facilities for plug-and-play installation. Fuse failure detection, voltage visualization, and fast diagnostics via measuring sockets – all this has made the electrical system of Holmer machines easier for the technician to handle. The electrical unit of the machines is no longer an issue for the end user.

From Industrial to Automotive Solutions

The Terra Felis series has proven its mettle in worldwide use and set standards for gentle and efficient beet loading for over ten years now. In 2017, the company launched the Terra Felis 3, the most technologically advanced beet cleaner loader in the world. Terra Felis, the self-propelled beet cleaner loader, is a complex machine with hydrostatic drive. The patented VarioPick pickup device for the beets with its variable cleaning path, which can be controlled via the speed of the rollers, and the other cleaning paths require drive units. The transfer arm with sensor for fully automatic, uniform filling of the removal vehicles and the counterweight arm must be controlled and operated, and the driver’s cab is also movable and can be raised for improved visibility. In addition, there are various relieving automatic functions and the ergonomic control system with comprehensive monitoring of all components. Given the multitude and complexity of the control tasks, it comes as no surprise that the electrical systems of previous beet cleaner loaders were housed in two full-grown, hand-wired industrial switch cabinets. In the new model, the change from industrial technology with a switch cabinet to streamlined automotive technology not only brings significant cost advantages, but also improved aftersales service thanks to the worldwide availability of spare parts. Holmer will present the new and improved beet cleaner loader in November 2019, just in time for Agritechnica, the world’s largest trade fair for agricultural machinery in Hanover, Germany. The Terra Felis 3 evo also features a central electrical unit from Würth Elektronik ICS.