Power Consumption at a Glance

Some good news from the Federal Environment Agency in March 2023: Absolute energy consumption in Germany has fallen slightly over the past 30 years from 2631 terawatt hours in 1990 to 2407 terawatt hours most recently. Less encouraging for manufacturing companies: Industry continues to consume the most energy, namely 699 terawatts compared with the other sectors of households (670), transport (635) and trade, commerce and services (385). By far the most important energy sources in industry are gas and electricity.

Machine tools play a key role in the manufacturing industry sector, also in terms of total energy consumption. Turning, milling, EDM and other manufacturing-related machines worth around 71 billion euros were produced worldwide in 2021. They are durable capital goods and are sometimes used for more than 20 years and in multi-shift operation. The energy costs that occur from running these machines account for around 20 percent of a company’s total operating costs – so it is not hard to imagine that they add up to considerable values over the entire period of use. Since the accumulation of dramatic climate catastrophes and the current energy shortage, the topic of energy consumption by machine tools in production has moved into the focus of the manufacturing industry.

Energy Consumption has many Causes

Whether a machine tool is energy efficient depends on a number of factors. Are aggregates such as cooling lubrication switched on and off sensibly? Are pumps with controlled motors in use? Is the machine well maintained? Are there standby strategies when the machine is not in use? Even today, machine tools in many companies are often not switched off even when not in use for a longer period of time – whether out of fear that temperature-related effects could have a negative impact on accuracy, that problems could arise during startup, or simply out of convenience. In addition, you cannot tell from just looking at the machine which unit is consuming how much energy. If you want to make production more energy-efficient, there are many potential levers you can use. The path to this goal is always the same: perception, understanding, prediction, control, and regulation. Fraunhofer IPK has developed an integrated solution for perception and understanding. On this basis, mechanisms for prediction, control and regulation can be developed. But first: What do »perceiving« and »understanding « mean?

Perceiving the Energy Consumption

Fitness trackers have become an indispensable part of everyday life for many people. The aim of these little helpers is to document how fit we actually are. They use sensors to record data which is then aggregated to provide key figures, such as the number of steps we take every day. This allows us to perceive the extent of our physical activity. Energy monitoring works in a similar way: A monitoring system for machine tools records currents and voltages in order to calculate energy parameters and trace energy consumption patterns.

Understanding Interdependencies

If we did not know that there is a connection between exercise and fitness, then documenting the number of steps would be a pretty pointless endeavor. However, if we relate the recorded step values to the development of our fitness, we recognize the connection. We can then deduce from our experience how our fitness will develop, if we walk more or fewer steps. If we transfer this logic to the topic of energy efficiency, documenting the energy consumption of certain production processes helps to understand whether these processes are energy efficient or not. Once these relationships are understood, measures can be derived to increase energy efficiency.

Setting up an Energy Monitoring System

In order to document where and in what context how much energy is consumed, Fraunhofer IPK has developed an energy monitoring solution that can be retrofitted to machines without much effort. The essential components are a power analyzer, three current transformers and a singleboard computer. Built into a box, the system is connected between the machine and the mains supply. If required, however, the components can also be installed directly in the control cabinet. From the phase current and voltage curves, the power analyzer generates all the energy characteristics required by energy management systems according to ISO 50001. These are transmitted to the single-board computer via Modbus. An MQTT client installed on the single-board computer then sends the data as a so-called publisher to an MQTT broker, from where it is forwarded to any subscribers of the data, for further processing, for example by an IoT platform in the cloud. Implementing this step creates the basis for optimizing the energy efficiency of production plants.