For producing medium-sized companies, energy is a significant cost factor in the value chain. Nevertheless, the responsibility for the topic of energy is usually located in different areas. It is rare to find a central contact person for the topic of energy. If a decision is now made to introduce an energy management system, we often observe the same challenges. This article gives an overview of which problems occur repeatedly in energy management in medium-sized companies and how they can be avoided.
Energy management must be part of the overall corporate strategy so that it can be successfully implemented. Thus, the topic must also be located at the management level and enjoy a high level of attention. In order to be able to successfully realize energy-related goals as part of the corporate strategy, the necessary framework conditions (resources, budget) must be actively created by the management.
Because of a lack of time and resources, the recording of energy data is usually carried out with the help of temporary measurements in medium-sized manufacturing companies. The procedure is pragmatic and certainly provides initial clues. However, the knowledge gained from the data obtained is usually limited. Temporary measurements are – as the name suggests – temporary and therefore only offer a snapshot of energy consumption. No continuous data series are recorded. This makes it difficult, for example, to understand more precisely the seasonal influence of the seasons on energy consumption. It is also difficult to understand the causes of critical plant operating states.
Temporary measurements are usually carried out with the aid of measuring clamps or Rogowski coils. The results of the measurements are usually only conditionally meaningful.
A study by PwC shows that companies that clearly assign the responsibilities and tasks of energy management in the organization achieve an average of 15.6% higher energy cost efficiency. It is to be examined whether for smaller enterprises the creation of a full-time position of an energy manager is worthwhile itself.
In principle, however, it could be stated that companies that equip the energy manager with their own budget achieve an average of 8.3% higher energy cost efficiency.
The energy topology in most companies starts at the billing-relevant meter of the energy supplier or metering point operator at medium-voltage level. This is followed by the transformers, which in turn feed the low-voltage main distribution board. Below the distributions, the individual machines and systems follow.
Here the question arises, where do I start to measure? Since each individual measuring point represents a cost factor in the acquisition, it makes sense to create a measuring concept adapted to the respective company. The measuring concept then determines the number of measuring points. Here it is important not to include too many, but also not too few measuring points.
Our experience shows that a measurement of all consumers is usually not necessary in order to increase the large saving potentials. Nevertheless, the billing-relevant meter „above“ the transformers should always be included in a continuous measurement in order to be able to determine losses during transformation in combination with a measurement „below“ the transformers. When purchasing meters, it is important to make sure that they are not oversized with their capabilities.
For example, the purchase of network analyzers only makes sense selectively on particularly sensitive devices. In addition, the largest consumers within the company should always be equipped with measuring points first. Depending on the size of the unmeasured remainder, an expansion of data acquisition should be considered. If it is not clear which system is responsible for the consumption characteristics, further measuring points should be considered. A large number of meters alone does not guarantee correct and reliable metering.
Exemplary electrotechnical topology of an industrial company. Starting at the feed-in point at medium-voltage level (20kV) and passing the billing-relevant meter to the transformers at low-voltage level (400V).
Often there is the assumption that the billing of the energy supplier is sufficient to operate energy management. However, billing only involves aggregated consumption values for the billing-relevant meter. Here it can certainly be observed whether there have been fluctuations in consumption over the billing periods, but a real gain in knowledge from the values is not possible. If, for example, a new peak load is reached in production shortly before the end of the month, it is hardly possible to make a valid statement about which consumers were essentially involved in the formation of a new peak load with the help of billing or the 15-minute values of the load profile. A high-resolution continuous measurement of the transfer counter as well as of the distributions or machines provides significantly greater insights, which also offer an opportunity for concrete measures. With the data basis of a continuous recording and analysis of the energy data, savings potentials can be reliably identified and specifically leveraged.
A new peak load occurs when the average active power within 15 minutes is above the last value of the peak load memory.
Many companies already have a variety of production measurement points that have grown over time. However, these are only recorded irregularly and mostly analogously using the „sneaker principle“, with an employee running through the individual measuring points to record the data and recording them by hand. The data is then transferred manually into digital form – for example an Excel spreadsheet. The process is time-consuming and error-prone. Various company divisions have the necessity to work with the recorded energy data. Controlling, for example, is interested in a consumption figure per output quantity that is as precise as possible in order to make a better cost calculation, while maintenance is more interested in why a machine requires early maintenance. This results in data silos. Each area creates its own Excel solution or database to further process the manually recorded data. In addition to the low data quality associated with manual meter reading, this procedure is costly and leads to double data storage. This can be remedied by digitally recording the data in a central database and software, which is available to each area according to the individual data requirements. The combination of digital acquisition and centralisation of the data ensures the same high data quality for all areas of the company with reduced effort.