development of an energy conservation profile that uses SERCOS III real-time
Ethernet communications is targeting energy reduction for controls, drives and
Target areas include reducing the
permanent load at motor/machine standstill, and dynamically adjusting energy
consumption depending on the process by considering the target completion
times/dates (partial load operation). A third target is saving energy by
switching off components during processing that are not required at a
particular time or point in the process (partial machine operation).
in discrete manufacturing, there is a lot of dead time where energy isn't
consumed by machines doing useful work," says Scott Hibbard, vice president of technology
for Bosch Rexroth Corp.
The problem is that there is no easy way to
get usage information from the peripherals in a system that might be running on
a continuous basis, even though many drives already have enough intelligence
inside to know what energy they are consuming.
"But until now, there hasn't been a standardized
way to provide that information back to the control so it can be factored into its
decisions. That's the purpose of SERCOS energy profile: to provide a standardized
way of passing energy-savings-related information from peripherals up to the
control to make more intelligent decisions," Hibbard says.
The SERCOS Energy Profile allows the
machine controls to switch connected components (drives, I/O and sensors) into
energy-saving conditions, up to complete shut-down, in a targeted form. It
makes each component's energy consumption transparent and allows for an
intelligent control of loads.
The profile also considers energy-saving
conditions for predictable breaks such as lunch breaks and plant holidays. At
pre-defined times, components are brought into a standstill condition in order
to save energy and, shortly before the end of the interruption, provides for
re-initialization of the components in stand-by to make them available again in
a precise way.
"It sounds simple at first, but it gets
complex when you say now let's all speak the same language," says Hibbard. "Let's
all pass the information up to the control in the same way, and let's all react
to information coming down to us in the same way. That's been the work of this
He says Bosch Rexroth has begun implementing energy-saving
functionality in some of its controls, but without a standard, there is a
problem doing it across the board with all peripherals. Bosch Rexroth's MTX CNC
line already has screens available where a customer can say, "If a device is
not used for a period of time, go to low-energy mode."
"In the beginning it can be used just like in
Windows, where you have a screen under the control panel for power settings,"
Hibbard says. "The system can be instructed after two minutes to shut the
screen off; after three minutes shut the hard drive off; and after seven
minutes put the whole machine to sleep. This is exactly the same thing."
The University of California at Berkeley has
a group called LMAS (Laboratory for Manufacturing and Sustainability) which is
doing research in this area. The question is where do we consume and where
could we save, and how much idle energy is wasted on manufacturing equipment? Hibbard says he has seen some studies that estimate
that as much as 50 to 60 percent of the energy consumed by a machine is
actually not used to produce product, but is rather wasted or idle energy.
"But users can start simple and work their
way up," he says. "Just having a tool to be able to easily command a peripheral
to idle down or sleep will help. Or users can set it up with a button on the
screen that says "lunchtime" because right now, many machines are running all
of the time. There can be very big impact with this technology but it is also
Click here for more information and an 8-page
white paper on the SERCOS Energy Profile.