Automation & Control
Mark Freeman looks at implementing active energy management in automated plants.
Mark Freeman untersucht die Realisierung eines aktiven Energiemanagements in automatisierten Anlagen.
Mark Freeman envisage la mise en oeuvre de gestion active de l’énergie au sein des usines automatisées.
Energy management key during plant downtime
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Diagram 1. Energy demand during breaks with and without PROFIenergy; the operating curve shows that even during non-productive operation a great deal of energy is required and high costs are incurred. PROFIenergy makes it possible to reduce these considerably or eliminate them altogether.
y selectively switching off any energy consumers that are not currently in use, the demand for energy and the associated costs can be drastically reduced. This is particularly relevant
to downtime in production. During breaks in production, many energy consumers continue running even though they are not required. This is where PROFIenergy can be applied, switching off these units during breaks in production in order to save energy and money.
Current situation Diagram 1. shows, on the left, a typical operating curve of a welding robot that was tracked over a period of several weeks. It can clearly be seen that even during the non-production time at the weekend, the energy consumption of the plant is still approximately 60 per cent of the level during production. Until now, such loads have not normally been
switched off. The reasons are complex: in particular, additional hardware would have to be installed externally on the machines. Many users balk at the engineering work
required for this. If, however, an ‘energy-wasting’ component could be directly switched off by the higher-level controller, additional hardware would be unnecessary. The user would only have to send a command
from the user program to switch off the unit and subsequently another to switch it on again (Diagram 2). At present, external cabling (for example, a
distributed station equipped with relay modules) is necessary in order to switch off the energy consumer. However, in future this will not be necessary as PROFIenergy commands can be used instead. The energy consumers themselves “speak
and understand” PROFIenergy, as they have corresponding energy-saving measures already integrated into them. By relocating this switching to the device,
manufacturers can decide how to optimise their devices in order to save the maximum amount of energy. Hard, external switching means that some loads must continue running during short breaks, as they would otherwise not be ready to resume operation promptly at the start of production However, with PROFIenergy, the manufacturer
has the flexibility to switch off certain parts of the machine rather than the whole unit. This means that during short breaks only the
parts which are quick to reinstate can be switched off, where as the entire unit can be switched off during longer periods of downtime. This means that the manufacturer can maximise the energy savings. PROFIenergy is extremely easy to use. Using
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