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Three more case studies - a theater in Cleveland revamps with PROFIBUS to control its scenery, an Australian water company standardizes on PROFIBUS for its plants, and a Dutch chemicals plant opens up the way to more efficient plant management using PROFIBUS.

NORTH AMERICA / THEATER: In Cleveland, Ohio, PROFIBUS forms the backbone for the new stage and scenery control system that was recently installed at the renovated Hanna Theater in the Playhouse Square region of the city.

In refurbishing the 87-years old theater, the owner envisioned state-of-the-art moving stage platforms and scenery panels. JR Clancy, Inc. of Syracuse, New York, a leader in theatrical stage rigging, was hired to manage the automation. Clancy installed a Siemens PLC for overall supervisory control and servo motor control for the movable scenery. To implement a hydraulic control system for movable stage platforms in the theater, Clancy hired Atlantic Industrial Technologies, Inc. of Islandia, New York, a specialist in fluid power and motion control.

The role of the hydraulic system is to control the height of three movable stage segments that project out into the front seats of the theater (see below). All of the stage sections are independently controlled and can move at two feet per second! Rated at up to 20,000 pounds load (including the stage itself), each section is raised and lowered by two hydraulic cylinders working in parallel. The hydraulic cylinders are buried in the floor of the pit and the hydraulic power unit is located in the basement behind doors in a soundproof room.

One of the obvious benefits of using a multi-axis electronic motion controller in this application is being able to rely on the controller’s ability to synchronize smoothly the motion of multiple axes. If one axis were to get ahead of the other, or lag behind - even by a small amount - the lift mechanism could jam and create problems for the operators.

There are also hidden benefits in using a motion controller for this application that are directly linked to the safety of the actors and the risk of equipment damage. Without a programmed motion controller, a component failure has the potential to cause a stage to bear the full force of a mis-commanded hydraulic cylinder. Even a small hose rupture can result in substantial steel guide damage, as the stage becomes ‘cocked’ if it is not positioned accurately on both sides. If actors (or scenery) are riding the stage during this type of failure, there is potential for serious injury. At the very least, this failure would cause loss of revenue for the owners and embarrassment in the theater community.

To manage the system properly and perform the necessary safety checks, the control system integrator selected the RMC75 two-axis electro-hydraulic motion controller made by Delta Computer Systems, Inc. of Vancouver, Washington (right). Three Delta controllers were used to handle the six axes of the three stage segments, providing a direct interface with PROFIBUS communication to the PLC.

The motion controller is programmed to perform multiple hydraulic system ‘health checks’ before every stage move. In addition, it continually checks and compares the position of both sides of a moving stage (reported by position transducers on each cylinder). If one hydraulic axis reports a fault, then the controller stops motion on all six axes of the three stage platforms. The software was thoroughly tested to detect and protect against various failure modes. The Delta RMC75 also employs digital inputs to monitor other inputs, including the brake sensors, ‘filter-dirty’ sensors, ball valve sensors and e-stop buttons and reports any faults to the PLC over PROFIBUS.

Analog inputs (on the motion controller) provide a means to monitor the hydraulic pressure of the cylinders. With all of its I/O capability, the Delta controller can be viewed as a general-purpose controller that combines fast, precise closed-loop motion control with additional functionality that would otherwise be performed by a PLC. DELTA COMPUTER SYSTEMS.

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AUSTRALIA / WASTE WATER: The key factor driving investment in wastewater treatment all over the world is cost reduction, and the only way to maintain high standards while reducing costs is to utilize highly sophisticated measurement and process control technology.

The introduction of fieldbus has dramatically boosted the monitoring of instrument status, maintenance and diagnostics. “The demand for high-tech automation in the water sector continues to grow rapidly in Australia and throughout Asia Pacific,” says Nick Smith, Manager, Tyco Process Automation Division. The company has been accredited by PI as the first PI Competence Center (PICC) in Australia. “The Tyco Process Automation Competence Center will play a major role in spreading the technology throughout this region,” says Smith, who is also PICC Manager.

To date, one of the country’s most comprehensive applications of PROFIBUS is at the $28 million Water Corporation-owned Kwinana Water Reclamation Plant (KWRP). This is one of Australia’s largest municipal wastewater reuse plants, and has implemented PROFIBUS DP and PA communications which are integral to the facility’s success in improving both water efficiency in the Perth basin, and environmental management in the Kwinana industrial area.

Water Corporation has been implementing PROFIBUS DP and PA networks for over five years in its water and wastewater treatment plants. PROFIBUS DP and PA will become an integral part of its planned networking of all the metropolitan water treatment plants over the next five years.
The Corporation’s Principal Engineer, Electrical, in the Mechanical and Electrical Services Branch, is driving a philosophy to intelligently connect the five largest water treatment plants within a 50km radius of Perth, to enable after-hours operation from the Corporation’s Operations Center in Leederville. For this to be deemed successful, an experienced operator in Leederville must be able to perform detailed diagnostics of any instrumentation or control issue and then decide what action is required. PROFIBUS in the plants makes much of this possible. www.profibuscentre.com.au

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NETHERLANDS/ CHEMICALS : The Dutch chemical corporation Nedmag is the leading supplier of very pure synthetic ‘Dead Burned Magnesium Oxide’ in Europe. The raw material processed at Nedmag Industries Mining and Manufacturing is extracted from deep inside the earth. To achieve this about half a million tons of magnesium chloride salt are extracted by Nedmag every year.

The installations have evolved into an automation mix of assorted controls, process control systems, remote I/Os and field devices. On top of that, various components use different communication protocols and device integration technologies, making vertical integration a real challenge.

“The big idea was to make all devices accessible from one central point,” says Wim Zomer, Head of Technical Automation at Nedmag (pictured left). FDT technology and Yokogawa’s FieldMate were chosen as for device management as communication with all devices of all protocols and integration technologies was requested. Through Trebing & Himstedt’s ETHERNET-PROFIBUS-INTERFACE xEPI, Nedmag staff can access FieldMate via an Ethernet network. “The brilliant thing about the concept is that we can use the infrastructure already existing in each room,” says Zomer. “Via secure internet connection, members of the team can even connect and act at night or during weekends from home if necessary.”

In combination with the TH DTM for the ET 200M Siemens Remote I/O, HART over PROFIBUS is available and accessible independently of the system provider. The integrated and central solution at Nedmag saves money throughout the complete plant life cycle and opens up the way to more efficient Asset Management. TREBING + HIMSTEDT