Renewable energy sources like solar and wind power generate direct current (DC) power, which, when used directly, can reduce energy loss from conversions. WITTMANN is utilising DC networks to enhance overall energy efficiency.
WITTMANN
The development of renewable energy moves power supply via direct current networks into focus. Solar power, wind power and other types of renewable energy are all generated in the form of direct current (DC). However, the normal power supply comes in the form of alternating current (AC). Therefore, transformers are interposed to enable the use of alternative energies. For transport and distribution, DC is transformed into AC – and in some cases converted back into DC at the point of consumption. In both industrial production and normal daily life, DC is constantly being transformed into AC and vice versa, and some of the energy is lost with every conversion. This reduces the energy efficiency of the applications. Here, the creation of DC networks parallel to the existing AC power supply offers the advantage of providing the generated DC power unconverted for direct use. The conversion losses still incurred on the way from an in-house photovoltaic system through direct voltage converters to the processing machine are by comparison absolutely minimal.
All set for series production
At K 2022, WITTMANN presented for the first time a DC-powered all-electric EcoPower injection moulding machine as a conceptual study. A robot from the WX series, also directly supplied with DC current via a joint interim circuit, took care of handling the finished moulded parts.
Together with its partner company innovenergy, WITTMANN has now brought DC injection moulding technology up to series production maturity. innovenergy specialises in installing DC networks in industrial plants and other areas, as well as developing and producing particularly sustainable solar power storage batteries operating with sodium chloride (common salt). The interim storage of solar current in batteries is also more energy-efficient in DC networks than with using AC networks and inverters.
Twofold increase in energy savings
For the Competence Days 2024, WITTMANN has been extending the range of injection moulding components available for use in DC networks by adding temperature controllers. The new Tempro plus DC reaches exactly the same high performance rates as the equivalent conventional Tempro plus AC-powered models. For instance, the Tempro plus D90 DC presented at the Competence Days, suitable for temperatures of up to 90°C, has a heating capacity of 9 kW with 750 V DC. The cooling capacity is 40 kW for a differential temperature of 75 K.
The DC version already comes with a 1.1 kW synchronous motor and an inverter as part of the standard equipment package. The motor drives a seal-less submersible pump with a maximum working pressure of 7.5 bar and a maximum flow quantity of 60 l/min. In cavitation-free operation, practical values of up to 40 l/min and 5 bar are reached. The inverter enables direct connection to the machine’s interim circuit as well as speed control in line with the desired process parameters. In this way, conversion loss is prevented and the pump speed is adapted to the requirements of the process. The result is a two-fold increase in energy efficiency.