Integrated safety for water treatment plant

WHILE the safe, productive interaction between man and machine is becoming increasingly important, the growing 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, adapted to suit operating personnel rather than the machine’s functionality. The objective is to keep the operator fully informed and provide targeted diagnostic support when an error occurs. 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.

The wastewater 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, the process 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, and provide advice on how to rectify the fault.


One safety system, many 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.

Good diagnostics for high productivity

On complex plants in particular, the integrated diagnostic function is an essential part of the overall concept. Here Glastechnik Holger Kramp uses PMImicro diag operator terminals from Pilz. It has three operator keys, four cursor keys and is simple and intuitive to operate. The transflective display increases the contrast in accordance with the ambient brightness. There’s quality inside the operator terminals too, for the integrated diagnostic concept PVIS offers users a range of benefits.

With PVIS, the PMImicro diag is all ready to just plug-and-play. All system messages from the PNOZmulti are displayed without any prior configuration.

The PMImicro diag and/or the safety system’s software tool (the PNOZmulti Configurator) provides pre-defined messages for all types of safety devices for plant or machine-specific diagnostics. That saves a lot of time during configuration. The user can customise every message within his application, from problem description through to proposed solution.

Intelligent error management on the PMImicro diag means that during operation it can display the most relevant event. In this case a conscious decision is made to move away from a chronological display, so operators receive the most important information at first glance.

That way the user is always up-to-date: if the machine stops, the display indicates the source and cause of the fault using easy-to-understand plain text messages. The diagnostic unit advises the operator on how to get the machine operating again as quickly as possible.

Regardless of the production process in which the water treatment systems are involved, the integrated Pilz diagnostic and safety concept ensures the highest level of safety and guarantees solutions that are user-friendly, with simple diagnostics, reliability and flexibility.

The PNOZmulti safety system is multifunctional, freely configurable and tailor-made for use in many areas of mechanical engineering. The system monitors safety functions such as E-STOP, safety gates, light beam devices, two-hand controls or pressure mats, and can also undertake standard control functions.

Various expansion modules are available to extend the modular system; these can be used in any combination: I/O modules for safety and standard control functions, modules for connection to all common fieldbus systems, plus safe speed and standstill monitors.

The safety system can be combined with Pilz sensor technology to form a co-ordinated, complete solution for secure safety gate monitoring. Mechanical, non-contact magnetic and coded safety switches are available for safety gate and position monitoring.

In conjunction with the operator terminal PMImicro diag and the Pilz diagnostic concept PVIS, the PNOZmulti offers fast, intelligent, user-friendly diagnostics. Machine manufacturers and system integrators can configure the operator terminal with just a few clicks of the mouse in the PNOZmulti Configurator. Ready-made, pre-installed texts, which can be adapted and expanded at any time, make the task even easier. In the case of a machine standstill, the cause of the fault is indicated on the display in easy-to-understand plain text messages. PMImicro diag also displays advice on how to get the machine operating again quickly. No need for time-consuming troubleshooting; advice regarding the right solution is there on the machine. That saves around 50 percent of the time needed to rectify an error.

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