The task of the sodistore max storage battery is to ensure a constant voltage, even when different consumers are connected and the supplied power fluctuates. Inesco’s solar power storage batteries come in various s and storage capacities of up to 500 kWh. These salt batteries achieve the same energy density and the same volume as conventional lithiumion batteries, but can be charged and discharged at much higher rates. The sodiumion battery is significantly more environmentally friendly and also safer than conventional lithium batteries. It does not require any hazardous materials and can be fully recycled at the end of its service life. In addition, it does not require any air conditioning and can be operated both in-doors at higher temperatures (up to 55 degrees) and outdoors at very low temperatures (-20 degrees).
For integration into the DConnect Microgrid, Wittmann is initially offering its EcoPower series of injection molding machines and the DC models of its WX linear robots. Further machine models and peripheral devices for integration into DC grids are in ongoing development. At its Competence Days Event in summer 2024, for instance, Wittmann unveiled DC temperature-control devices.
In order to operate these safely, the connection technology also had to be adapted. Specifically for this application, the Harting Technology Group developed a prototype for an electrically lockable connector. During operation, this protects both the system and the employees from unintentional pulling and the associated electric arcs. The integrated signal indicator shows at all times whether voltage is present at the connector or not.
The all-electric EcoPower machines, which are equipped with highly dynamic servomotors for driving the main movements, are ideal for use in a DC grid. They feature a patented kinetic energy recovery system (KERS) that converts kinetic energy into electrical energy during braking. In a conventional AC setup, this recovered energy can only be used inside the machine, e.g. to heat the barrel. When integrated into a DC grid, however, it can also be fed back into the DC grid for use by other consumers or for storage within the battery. The DC model of the Wittmann robot, which is supplied directly via the DC link of the EcoPower machine, also feeds excess energy back into the DC link when braking.
The production cell presented at the latest trade shows comprised an EcoPower B8X 180/750+ injection molding machine with an installed salt storage capacity of 45 kWh. It operated non-stop over the entire eight-hour trade-fair day without the need to switch to the AC grid at any time.
Cutting Energy Consumption by up to 15 Percent
Initial practical tests show that the reduction in conversion losses alone shaves up to 15 % off the power demand of a production cell supplied direct with DC. Any
decision-making about whether or not to create a DC grid should not focus on whether one technology is superior to the other. Instead, DC grids will be set up alongsi-de AC grids in more and more areas. For example, if the battery storage becomes exhausted at some stage on an overcast day with little sunlight, the system developed jointly by Wittmann and inesco will automatically switch to AC. The switch will not be noticeable in production; the machine will be fed with a continuous, steady supply of power.
In the long term, too, it is likely that AC and DC grids will exist in parallel. This will allow decisions to be made on a case-by-case basis as to which power supply offers the greatest overall efficiency.
Technical Challenges Solved
How quickly will DC become established in the injection molding industry? There is no easy answer to this question, as many factors are involved. The first task is to publicize the possibilities and advantages of DC technology more widely, to find reference applications and to share experiences more intensively across industries.
The technical challenges, at any rate, have been solved. Industrial-grade solutions, components and protection mechanisms are available. However, what is needed more than that is a change of awareness. Factory planners, architects, electricians and energy consultants need to be made aware of DC technology, so that it can be considered from the outset when new investments are being made.
Politicians and industry associations also need to play their part. Having recognized the key importance of renewable energies for the energy transition, the German government launched its first joint research project back in 2016. This led to the emergence of the Open DC Alliance (ODCA) working group within the German Electrical and Electronic Manufacturers' Association (ZVEI) in 2022. Many well-known global companies have joined the ODCA, including inesco.
ROI Possible in Just a Few Seconds
Although existing photovoltaic systems can be converted to direct DC power, repla-cing all inverters with DC-DC converters would be a massive undertaking. The fas-test return on investment when setting up and operating a DC microgrid is made at the time a new DC-coupled photovoltaic system is being installed. That way, power and load management can be optimally designed from the outset. It is also advisable for the DC network to integrate not only the injection molding production cells, but also the peripherals and parts of the infrastructure, such as the compressed air supply, lighting and air conditioning.
What most affects the ROI, though, is the stability of the power supply on location. Where power supplies are frequently interrupted or the amount of supplied power is restricted, a DC microgrid with DC-coupled battery storage pays for itself particularly quickly. In the case of very critical components, the payback on a DC power supply can be made in a matter of seconds when a blackout occurs
