The industry's desire for increased efficiency, improved control characteristics and highly dynamic machines has also reached the agricultural sector. The electrification of agricultural machinery and vehicles can make this possible. As the market differs significantly from the automotive sector - a combine harvester is more of a moving and producing machine than an automobile - the electrification of tractors, other agricultural machinery and auxiliary units opens up completely new perspectives and potential. Tractors that are electrically powered and/or generate electricity can, for example, supply a seed drill, fertilizer spreader or rake with energy. Electrified agricultural machinery increases efficiency and productivity and can also reduce the susceptibility of electric motors to maintenance and faults.

The application of electric drives to fans and metering units, for example, increases the efficiency of a seed drill from 60 to 85% compared to hydraulic motors. In addition, the more targeted use of operating materials such as seed and fertilizer and the optimized controllability of the attachment result in a significant reduction in power and fuel consumption. At the same time, the less complex design reduces the required installation space. Data generation and data management must also be considered a prerequisite for precision farming.

The interface issue

In electrification, the interface between tractor and implement is of crucial importance, as the products offered by various tractor manufacturers must be compatible with those of different implement manufacturers. This means that in addition to a standardized interface for data - the Isobus - an equally standardized interface is required for the transmission of electrical energy.

The 'tractor connector' is the first Harting product developed exclusively for agricultural engineering. It complies with protection class IP69 K in mated and unmated condition and operates in a temperature range from -40 to +85 °C.

© Harting

This standardized interface for direct and/or alternating current was previously lacking. Connectors previously installed in the machines are not suitable for distributing a correspondingly high electrical power within the tractor and on the attachment. This is because the energy requirements of a sprayer (1.2 kW), a seed drill (3 kW) or a mulcher (140 kW) cannot be covered by standard 12 V generators with an output of around 1 kW.

To remedy this shortcoming, a committee was founded in 2008 to standardize various agricultural topics - the Agricultural Industry Electronics Foundation (AEF). The Harting Technology Group joined it in 2011. In cooperation with the members of the AEF and all major agricultural equipment manufacturers, the required standardized interface was developed - the 'AEF High Voltage Connector' for the transmission of 480 V(AC) or 700 V(DC) between tractor and implement.

The AEF high-voltage connection

The AEF high-voltage connections are a special technology designed to meet the future power supply requirements of auxiliary units and implements. This supports the development of fully electric and hybrid drive systems on tractors as well as the increasing demand for electric drives on implements.

The 'AEF High Voltage Connector' was designed for the power supply requirements of auxiliary units and attachments.

© Harting

The 'tractor connector' is the first Harting product developed exclusively for agricultural technology. It complies with protection class IP69 K in mated and unmated condition, operates in a temperature range between -40 and +85 °C and is designed for a maximum output of 150 kW at 480 V(AC) or 700 V(DC). The high-voltage interface is designed so that both AC and DC concepts can be transmitted. With DC, a DC voltage of up to 700 V generated on the tractor is transmitted to the implement, where it can be used and specifically controlled by several actuators (motor including frequency converter). With AC, this FI unit is on the tractor; this means that it is only possible to address or control one actuator unit on the implement. As the 'intelligence' remains on the tractor with the AC solution, components on the implement can be saved.

The DC version, on the other hand, only requires one interface to supply all the electric motors of the implement.

Outside of standardization, the new interface is also used as a 48 V connection with a maximum output of 10 kW.

As a protective measure, the interface has a break-away functionality: In the event of an extreme error on the part of the user, where the plug has not been disconnected after disconnecting the attachment and the tractor drives off, the high-voltage unit must not be destroyed and a life-threatening situation must not arise. Break Away is virtually a predetermined breaking point at which the plug connector disconnects in this case.

Author:
Guido Selhorst is Head of Corporate Market Communication at theHarting Technology Group in Espelkamp.

The AEF

The Agricultural Industry Electronics Foundation - AEF for short - is an international body that deals with the electrification of agricultural machinery. Its members are manufacturers and OEMs in this sector who work together on new solutions. Eight manufacturers and three associations are currently involved as so-called premium members with 200 other members in the AEF's topics: improving the cross-manufacturer compatibility of electronic and electrical components in agricultural machinery and ensuring transparency in compatibility issues.

A central point of the joint work is the introduction of international electronic standards. In addition to the high-voltage connection, the committee is also dedicated to future Isobus communication standards (towards TCP/IP), wireless communication and smart farming.