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Safe, reliable, productive (Part One)

Supplier: Pilz Safe Automation
05 March, 2008

Automated water control Integrated safety concept for water treatment plant complexity of that plant and machinery is making their operation and management more and more difficult.

Help is at hand from innovative operator terminals and concepts, which are adapted to suit operating personnel rather than the machine’s functionality. The objective must be to keep the operator fully informed and to provide targeted diagnostic support when an error occurs, in order to keep downtimes to a minimum. The best recipe for this is: a universal diagnostic solution which fits perfectly into the relevant application and evaluates the information on every system.

The linking of various plant components as well as different types of production and procedural processes requires careful analysis of the possible error sources and potential hazards. A holistic diagnostic and safety concept plays a key role in minimising the risks to man and machine, identifying error sources quickly and thereby increasing the plant’s availability and reliability.

Treating water safely
Water is an increasingly valuable resource. Even within the industrial production process, the demand today is for creative solutions that deal sparingly with this valuable raw material. Glastechnik Holger Kramp GmbH in Germany ensures that wastewater from grinding, drilling and similar machining functions is cleaned and made available again to the production process in as short a time as possible. The water treatment systems clean wastewater containing a variety of pollutants via several filtration, decantation and release procedures, thereby making an active contribution to environmental protection. They are predominantly used in the glass, ceramics and chemical industry.

Systematic risk analysis
The plants consist of one or more tanks and container systems and operate in close contact with the production facility via incoming and outgoing water pipes and pumps. As water is known to conduct current, TÜV (a ? of certification authority) places high demands on safety. In conjunction with experts at Pilz, the company carried out a systematic risk analysis to minimise the risks to man and the environment and prevent damage to the plant. However, it was also important to develop a user-friendly, service-friendly diagnostic concept, which, in the case of a fault, would supply quick, specific information on the location and cause, provide advice on how to rectify the fault and thereby reduce downtimes to a minimum. “We set a high environmental standard and we wanted an equivalent solution for safety and diagnostics to go alongside it”, stresses Michael Kramp, the firm’s company secretary.


One safety system for a wide range of tasks
Pilz emergency stop devices (E-STOP buttons) and coded PSENcode safety switches guarantee safety in conjunction with the PNOZmulti and safety PLC. At the customer’s request, the multifunctional safety system also undertakes standard control functions. In specific terms the PNOZmulti monitors emergency stop devices operating locally and across the range of machines, as well as the link between the machines and the water treatment system: A fault around one individual machine does not immediately mean that the whole plant has to be brought to a standstill. However, if the central water treatment system should fail, this must result in a controlled overall shutdown of the plant. The safety system also detects potential shorts between contacts, monitors the speed of the pump motors and guarantees that they shut down in the case of a fault.

(cont. Part Two)