Author : Michael Babb
29 November 2009
The car manufacturer, Mr. Schott explained, set a goal of reducing the amount of energy input per unit produced by 20% over the five-year period from 2007 to 2012. The steps implemented to achieve this goal included measurements in car body production, which very clearly indicated a high amount of energy is required —even during production breaks when the machinery is idle.
Not doing anything can cost the company a lot of money.
Non-production periods can also be much shorter, as when German autoworkers pause for breakfast in the morning, or take time off to have a bottle of beer during their afternoon rest period.
Studies show the production cell under review went on using approximately 60% of energy over the weekend. That’s 60% of what it normally uses during the actual production process.
“This is exactly the type of potential that needs to be leveraged,” said Mr. Schott. “Today, measures are taken here and there to reduce energy consumption in production but so far nobody has closely considered the issue of production rest periods.”
The case for ProfienergyClearly, the auto industry sensed the need for improvement.
AIDA, the Automation Initiative of German Automobile Manufacturers, called on PNO, the Profibus user organisation (Profibus Nutzerorganisation e. V.), at the end of 2008 to design a non-proprietary profile called Profienergy.
The intention of the profile is to provide a simple way to centrally control the cut off of unused loads during production rest periods. It was to be based on the Profinet industrial Ethernet standard.
Work started on the project early in 2009 and involves thirteen companies working in the automation industry, including Siemens. The paper is currently being reviewed by PNO and is due to be available in an approved version early in 2010.
Initial Profienergy products from Siemens, as well as other companies, are expected to make their appearance in 2010.
Why not just turn it off?
Why do you need complex automation and communication profiles to turn off a machine when it is not being used?
Solutions applied in the past, which involved manual cutoff during production rest periods, are time-consuming and unreliable, said Mr. Schott.
Profienergy allows unused loads to be automatically switched off during rest periods or their power consumption to be automatically reduced.
It helps cut the power consumption by selectively cutting off individual functions and/or devices, not only during major stops but also during short breakfast breaks, he explains.
Profienergy will use a standardised data set which enables simple programming of even complex switching operations.
The new standard will be applicable to all manufacturing industries and industries with typical production rest periods.
Siemens involvementMr. Schott described Siemens’ approach to continuous energy efficiency improvement as a process encompassing three stages: identify, evaluate and then realise.
“By Identify we mean to show very clearly the amount of energy a machine or plant uses,” he said. “Here we apply the Simatic powerrate energy management system, in combination with underlying measurement techniques, and by achieving this first step we create a greater awareness of energy needs.”
The second stage, evaluate, analyses the potential scope for improvement.
Finally, in the third stage, realise, the identified and evaluated measures are implemented with a view to achieving the objective of a more energy-efficient plant.
“It is in this stage that Siemens offers, for instance, more energy-efficient drives for the process level and a load management system in the form of Simatic powerrate,” said Mr. Schott.
Simatic powerrate will temporarily cut off certain loads in auxiliary systems if an overload situation is anticipated.
At this point he gave an advertisement for Siemens energy savings products: “Siemens provides products and solutions to support every phase of the customer's energy management operations, ranging from the visualisation phase with Sentron PAC and power management software through the evaluation phase with Simatic powerrate and EOA, a service package for optimising plant energy usage, to the costing phase with solutions such as Sinasave and finally the implementation phase with products such as motors, inverters and soft starters.”
A case in pointMr. Schott gave a brief description of a project that his company worked on with Mercedes Benz. The goal was to identify the amount of energy used in a section of the production plant whose equipment includes Siemens G120D inverters.
The Simatic powerrate energy management system was applied together with the underlying measurement techniques. The energy required in the plant was analysed and displayed under varying plant conditions such as “system ON” or “system at standstill.”
The research highlighted improvement potential achievable by cutting off unused loads, for instance in the 400V and 24V level.
One result was the discovery that it was only necessary to start up the production line 10 minutes before the beginning of the shift.
Energy costs were also successfully reduced by using FU G120D drive systems which recover energy during braking.
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