Building section 12 is one of a number
of production sections that work around
the clock. Over the course of time, the
plants have been expanded and modernized
several times, in some cases with different
automation and visualization systems.
Thomas Dahl, project manager in the process
control department at Zott in Mertingen,
explained, “It's a true, evolved system
environment.” In the meantime, he too can
look back on a wealth of experience at Zott,
“We started around 20 years ago, at that
time still working with a plant constructor.
For the last three years, I have been directly
responsible for various automation projects
here at Zott.” Among other things, Thomas
Dahl has implemented several projects with
the Sistar control system from Siemens.
Sistar handles process operations in a wide
range of different areas at Zott in Mertingen
– including the whole operation from the
cold milk section through to handover of
the product to the filling machine in building
section 12. Dahl explained, “The jobs
are in our ERP system along with our entire
material and data management. We report
the corresponding jobs to the automation
level and return the data relating to stock
postings, material transports and completed
process actions to the ERP system. We
therefore need a control system that offers
all the functions required to control and
track the processes, so that it is also easy to
use for our colleagues in the control room.”
Coordinated functionality
According to Dahl, this is where Sistar offers
the right balance. “What we mainly like
about Sistar is that, in comparison to many
other systems, it does not offer excessive
functionality, but exactly what we need.” This
includes, above all, Route Control. He added,
“Route control is a core task of the instrumentation
and control used in our process.
We can also realize widely varying dosages
and recipes, and control and monitor tanks
and pipes. Our clean-in-place (CIP) systems
are also automated with Sistar and Route
Control in building section 12. In comparison
to other solutions, the system has a number
of advantages for our requirements.”
For example, Sistar offers the option
of easily tracking the progress of the job
through step sequencers. This is an important
feature not only for Dahl but also for
Linder and his colleagues in the control
room. In this way, at every point in time it
can be exactly determined which dosages,
mixing and heating processes have been successfully
completed, and which is the next
Technology/IT ¦ IDM
step. Linder stated, “It's a great help to us,
especially when a fault occurs, because we
can immediately see which conditions were
polled, which have to run next, and where
the process ground to a halt. In many cases,
we can then help ourselves in the event
of faults without having to call on our colleagues
in process control.”
Thomas Dahl and his colleagues also
use the step sequencer analysis for troubleshooting
and optimizations. Thomas
Bissinger, head of process control at Zott
added, “We also have the current version
7 of Sistar, with replay mode – another tool
which enormously lightens our workload.”
Replay mode enables all relevant process
data and parameters, including the corresponding
process images and dynamics, to
be played back later. Bissinger explained,
“This enables an error to be understood in
detail. For example, whether a valve was actuated
at the time in question. And the entire
error situation can be fully understood,
without having to subsequently reproduce
the sequence – which makes troubleshooting
much more efficient.” Previously, Zott
could also analyze error situations on the
basis of step sequencers and archive values.
Thomas Dahl added, “But now we can, so
to say, just look at a video of the relevant
process state, which certainly saves us 50%
of the time otherwise required for troubleshooting.”
Efficient teamwork across
several locations
The control system at Zott in Mertingen currently
comprises 25 Simatic controls, two
redundant pairs of servers, and 28 clients.
These clients and servers are implemented
High season at the Gourmet Dairy:
Depending on the season, up to 2.5
million liters of milk are delivered
daily to the Mertingen plant.
The core task of the control system
is route control with large numbers
of valve terminals, tanks and
pipes
“The step sequencer analysis is a great
help to us, especially when a fault occurs.
In many cases, we can then help ourselves
in the event of faults without having to
call on our colleagues in process control.”
Patrick Linder, control room technician,
Zott SE & Co. KG, Mertingen
Using the Sistar clients, employees
can also access all the relevant process
information on the production
line itself.
January/February 2021 ¦ international-dairy.com · 25
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