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Questions to Dipl.-Ing. Norbert Gemmeke
DC-Technology DC-INDUSTRIE is a project initiated by the ZVEI to promote the use of direct current in industrial environments. Together with partners, HARTING is also involved in this project. Could you briefly describe the content of the project and explain the importance you attach to it?

N. Gemmeke:

The DC-INDUSTRIE project is based on the German government's Green Paper, which calls for the priority implementation of energy-saving measures and consequently the decarbonisation effect of renewable energies. Initially, the focus was on the adaptation and testing of power electronic devices for the supply as well as the protection of DC grids in production cells. Building on this, DC-INDUSTRIE2 aims at the intelligent coupling of DC grids for production halls or large-scale process engineering plants. The special challenges lie in the interaction between suitable components and equipment.

We are involved in the DC-INDUSTRIE project because we see considerable potential for saving energy and materials and are convinced of the trend-setting effect of this technology for reducing energy consumption. In view of the great importance of this technology for sustainability, management is according these topics the highest attention. In the AC sector, normal plugging and unplugging of connectors is usually possible without damaging processes, but with direct current this will no longer be so easy. Nevertheless, what is it that makes the operators of industrial plants look for alternatives to AC solutions?

N. Gemmeke:

The damage caused "by improper use", i.e. pulling and plugging under load, should not be underestimated for AC and DC. This always refers to three aspects: Personal protection comes first, followed by component and system protection.

Renewable energies are becoming increasingly important in energy supply. These forms of energy are largely DC-influenced. In addition, there is the aforementioned goal of energy saving: when harnessing renewable energies, AC/DC conversion losses are eliminated. In combination with energy recovery measures, they lead to an overall reduction in energy consumption from the AC grid. The company saves energy costs and contributes to meeting CO2 emission targets. In addition, power consumption peaks can be reduced by using energy storage devices, which in turn saves costs. In parts of the world where power failures of more than 3 seconds are more frequent, a DC infrastructure with energy storage devices offers the possibility of bridging outages. What is the state of the art for DC interfaces? Which technical and systemic features have to be considered?

N. Gemmeke:

For the continuous use of direct current, we need a standardised plug face, as this is an infrastructure that will be universally applicable. A decisive factor for the acceptance of DC applications is that they can be plugged and unplugged safely. This can be achieved by means of an autonomous interlock in the connector or by integration into the control system of the plant or system technology. The alternative would be an edge/cloud solution. Four different unlocking phases for this were planned in the DC-INDUSTRIE working groups. We are working very closely with the company Perinet on this task. There are good synergies in terms of electronics, the processing of data in the connector and the intelligent connection in smart factory approaches.

"A decisive factor for the acceptance of DC applications is that they can be plugged and unplugged safely."

Norbert Gemmeke, Managing Director HARTING Electric GmbH & Co. KG The distribution of power inside and outside the control cabinet is a core competence of HARTING. What specific tasks did HARTING take on within the project?

N. Gemmeke:

HARTING is an associated partner of the cooperative project involving 40 industry partners. We operate within the framework of working groups, and this includes our work in the sub-projects overall concept, energy management and protective measures. Here, there are focal points such as interfaces for DC feeders, selectivity, insulation monitoring and ageing behaviour of insulating materials. The latter then results in central requirements for future interfaces. During a press event you announced a connector for DC technology. What technical requirements did you take into account when developing this connector?

N. Gemmeke:

We develop our connectors based on market requirements. HARTING is a specialist for heavy duty connectors. Against this backdrop, we currently see two possible versions of a DC interface. They differ both in the design of the plug faces and in the control system which releases the connector for plugging and unplugging. In the first version, contacts are provided for DC/AC supply and Ethernet communication. In the second version, contacts are provided for DC/AC supply, signals, Ethernet communication and pneumatics as well as for linking the release of sensors/actuators to a control system. Both solutions offer the required level of safety and protection, both personal and material.

DC-Technology What can be said about HARTING’s solutions or approaches? You spoke of prototypes that establish communication with SPS or with the cloud. Would you describe the solutions in detail?

N. Gemmeke:

Several sensors and actuators are used in the add-on housing for locking and operation. In two design studies, sensors and actuators are integrated differently into the communication. In one version, the release for plugging and unplugging the connector is controlled via a PLC and communicated to the higher IT level.

In the second solution, the control of the connector was directly integrated in the form of compact electronics that communicate via a simple Ethernet-based connection. The advantage of the integrated version is the seamless integration into the IT-based higher-level control system ("Factory Cloud") via IP-based communication. The plug and unplug applications are "operations" in the course of converting a machine or machine part. This second solution can significantly reduce the effort involved. In addition, the most important safety function, locking under load, is fully integrated into the connector in this variant.

Both approaches are still in the prototype stage and are available for initial applications in DC systems. In October last year, the research project DC-INDUSTRIE2 was launched. The DC grid is to be expanded into an intelligent DC grid for a production hall. In what time frames could applications be realised?

N. Gemmeke:

DC-INDUSTRY2 runs until 2022 and includes a number of model plants. The focus is on the benefits for the grid, modularity and the spatial extension of the infrastructure across entire factories. In this context, drawing up specifications is an important prerequisite for the implementation of DC applications. The second project phase is dedicated to a possible intelligent supply based on Industry 4.0 and energy efficiency measures. The simple connection of renewable energy sources and the flexible use of energy is crucial. Normalisation and standardisation must go hand in hand.   

Specifications and concepts will be tested in model plants. Applications in the meaning of deployable series components will be available in 2023, depending on the progress of the project.  

N. Gemmeke
Norbert Gemmeke, Managing Director HARTING Electric GmbH & Co. KG
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