Energy monitoring for conveyance technology and logistics
How is it possible to save energy, if it is very difficult to intervene in the major processes? Answer: By taking a precise look at the details. Hermes, a logistic company, is presently establishing an energy monitoring and energy management system in its dispatch centres, with the hardware and software package from Janitza. The engineering unit is also benefiting from this in other areas, such as preventative maintenance or fire protection.
Hermes is a company of the Otto Group and delivers comprehensive services for distance selling. Thanks to its commercial experience, the company manages the entire process chain and offers a service spectrum that encompasses the establishment and management of webshops, accounts receivable management, financial services and customer care, as well as warehousing, order picking, distribution and returns management. The largest of the four Hermes logistics centres (one of the largest in Europe) is located in Haldensleben near Magdeburg. Around 3,000 employees ensure that an average of 250,000 shipments leave the dispatch centre every day. It is possible to process up to 200 million articles there in a year.
Climate protection as a company objective
The board of the company owner, Otto Group, has agreed on a climate protection strategy that obligates all of the significant subsidiaries of the group to reduce their transport, mobility and site-related CO2 emissions by 50 percent by 2020 (in comparison to FY 2006/2007).
A separate project team is investigating the requisite measures within each company subsidiary, because the various structures of the companies cannot be mapped according to a standardised template. A project team of energy officers has been in existence for the four Hermes sites since 2009, the management of which works within the engineering unit. Team member at the Haldensleben site is Clemens Klein. He describes his position as follows: „The advantage of the engineering unit is that we are very closely involved. Within the framework of maintenance, we are able to utilise energy-saving parts right away where replacements are anyway due. However, we do require precise consumption data.“ He refers here to an aspect that affects all energy saving measures: Classic consumption data monitoring at a central point, as was standard for a long time, is insufficient for detailed power monitoring. In order to demonstrate the effectiveness of saving measures, it must be possible to individually assign the power consumption to the respective consumer groups (image 1).
The first step: Know what takes place
The shipping centre in Haldensleben went into operation in 1994 and has already been expanded three times. The buildings and systems are correspondingly diverse and widely spread. A building control system (BCS) is naturally integrated, which also facilitates consumer data logging. However, this does not deliver any detailed load profiles; instead only relatively roughly registered meter values. Furthermore, interfaces with other applications are rarely available. It is only possible to generate reports in csv format with additional, cost-intensive software.
The first step therefore had to be comprehensive determination of the „actual“ situation. Hermes is utilising the Janitza product palette for this. The UMG 96RM in particular is in use in large unit quantities. It is predominantly designed as a compact universal measuring device for use in low voltage and medium voltage distribution systems. It is capable of capturing numerous load profiles and energy data, as required for energy management systems (ISO 50001), for fault analysis or for monitoring the power quality.
Furthermore, a number of power analysers UMG 508 and universal measuring devices UMG 103 are also installed at certain locations. The first highly promising tests with the UMG 96RM-E for residual current monitoring (RCM) have also been running for a considerable time.
Clemens Klein explains the decision in favour of Janitza: „We have tested devices from various manufacturers, all of whom promised high accuracy of measurement and overall quality. However, the interfaces were a challenge. Some manufacturers only offer virtual serial interfaces. As long as one uses only a few devices that is no problem, but this was no solution given the anticipated number in this case. Thanks to their network interface, Janitza devices can be easily integrated in the existing data networks.“ As such, it was only necessary to replace selected analogue and digital devices for models with a network interface (image 2).
On a safe course in external networks
Hermes records the device data via the GridVis® software from Janitza. GridVis® sends the data to an SQL database, for which Hermes utilises an OPC server from Janitza. External applications − such as energy management − are available here, which Hermes utilises for further processing. In Haldensleben the power consumption data for all four sites is evaluated in this way. Alongside current, these also include water, gas and compressed air. Even steam, which is required in Hamburg for cleaning purposes, can be captured directly in this way. For this purpose, a system pulse counter is connected with an UMG 96RM, which in turn passes the data on via Modbus.
Detect hidden saving potentials
With the finely detailed record it is now possible for individual divisions such as goods acceptance or order picking to receive an energy report, divided up into the various, significant load groups. This not only enables very precise isolation of particularly power-intensive system parts. One also has an instrument at hand, with which to measure whether an action is actually having the desired saving effect.
In this way it was intended that the lighting of the rack aisles in Ohrdruf be retrofitted with control through movement sensors. The corresponding measuring devices were installed beforehand, and it was therefore possible to precisely document the saving – a valuable decision-making aid for other sites that are considering similar measures.
Conveyance systems consume a lot of power (image 3 and 4): Work takes place in the distribution centres up to six days a week. And even when switched off, the power consumption stands at roughly 20 % of operational consumption. The reason lies in the availability, which must be unconditionally intact. It must not be possible for the system to be at a standstill, because a controller no longer recognises „its“ participants in the network after being switched on and must therefore be reinitialised. Such faults can arise with a restart. Important load groups therefore remain switched on. It is also not permissible to simply switch off certain compressed air applications.
Unexpected additional benefits
Originally, the intention at Hermes Fulfilment was essentially to determine the consumption statuses and load cycles. However, the engineering unit is now utilising an increasing number of options, such as power quality reports updated on a weekly basis, which the division and maintenance managers can call up online. Possible frequency converter faults, high voltage of around 240 V or voltage dips of a good 10 V caused by a large sorter during start-up − such intermittent and irregularly occurring events can now be well isolated and documented. In this way it is also possible to locate the causes of problems retrospectively.
Reports are also expedient with replacements and expansions. Some system suppliers demand a power quality analysis, if they are to provide guarantees. The engineering unit is no longer required to utilise the services (subject to a charge) of the energy supplier.
A further application is operating hours optimisation. A sorter may exist, that is only required to start up half an hour after the shift begins (figure 5). It is also possible to illustrate where it is worthwhile switching off a device or the lighting during the lunch hour. A general instruction to save energy is not easy to implement, even with the best of intentions. However, energy monitoring transparently shows how much CO2 a specific sorter generates, which runs empty for half an hour. If this value is subsequently converted into a handy form, for example the equivalent kilometres travelled, then this can provide the little extra motivation that makes the difference between understanding and acting. In the future, it is even intended that monitors in the halls provide power consumption information at all times.
Further advantages with RCM (fault or differential current monitoring)
For practical reasons, the energy monitoring is also accompanied by residual current monitoring RCM, as provided for example by the UMG 96RM-E from Janitza. The additional cost is not high, although the additional benefits certainly are. For example, RCM monitoring makes complex insulation testing according to BGV A3 (German regulations of the trade associations; implementation instructions for accident prevention with electrical systems and equipment) superfluous under certain circumstances. With the high runtimes of the systems it is almost impossible to realise a shutdown.
The RCM also meets with the extensive fire safety demands. The risk of a smoldering fire due to an undetected insulation fault can be determined and prevented in a timely manner with the monitoring.
Less dramatic faults, such as a near-failure of a frequency converter for example, can also be detected in good time with RCM. This preventative maintenance provides effective protection against unplanned system downtimes.
At the end of the year Hermes will have a comprehensive energy management system, and in doing so will come a big step closer to the objective of climate protection.
Hermes Fulfilment GmbH
Janitza® electronics GmbH
Janitza electronics GmbH is a German company and has been active for 50 years in the manufacturing of systems for efficient power application, energy measurement and cost savings. As a globally renowned manufacturer of network monitoring and energy management systems, digital integrated measurement devices, power factor controllers and compensation systems, the company stands for the highest quality standards and innovations.
Products are manufactured according to leading-edge expertise with state-of-the-art production technology. At Janitza, quality management is an ongoing managerial task (e.g. ISO 9001). Comprehensive know-how, competent consultancy and concept generation, right through to the commissioning of tailored solutions, ensure fulfilment of customer wishes and requirements.