General:
Q: What industry (eg mining, food and beverage, automotive, etc) is the scada being applied in?
A: Petrochemical.
Q: Describe the application briefly giving a description of any existing control systems, any previous scada system that was in place, etc. If relevant, describe the switchover from the previous system.
A: The pipelines utilised by Sasol, running from Richards Bay to Secunda and from Sasolburg to Krugersdorp, Pretoria and Witwatersrand are monitored by means of a Moscad PLC and Adroit scada system. The system currently monitors 65 pressure-reducing stations along the network, approximately 800 km in length. The values of temperature pressure and flow are transferred via an X.25 backbone communications network to the Adroit scada system and distributed to 7 Adroit-based sub-centrals, connected via the Sasol WAN.
The network also has a standalone Adroit system in Durban, at Petronet. All of the values from the KwaZulu-Natal stations received at the Rosebank server are re-transmitted to the Petronet system across the X.25 backbone. The system also monitors the flow from Secunda to Sasol where it is connected to a sophisticated leak detection system. Any deviation from the normal is reported and the location of the leak is reported.
Due to the extensive network and large distances between the stations, remote diagnostic and remote software download facilities are necessary. This is achieved via the Motorola MDLC protocol. This is a proven 7-layer protocol and all functions are available over the X.25 network. The Motorola Moscad CPU300 is the core of the remote terminal strength. A back-up server will also be added to the Secunda plant as a hot standby system.
Q: Who did the system integration?
A: Alcom Systems.
Q: Approximately how many man-hours did the integration take?
A:It was a continuous upgrade over 5 years.
Q: How is the after-sales support handled (eg remote-dial-up, e-mail, Internet access etc)?
A: Via remote dial-up.
Q: What sort of licensing agreement is used on this particular system? Does one licence cover all modules, or can the user only buy those modules that he wishes to use?
A: One licence covers all modules.
System architecture
Q: How many tag points / I/O does the installation have? Analog? Digital? Maximum possible?
A: There are 350 analog and 200 digital tag points, but the system can be expanded to take an unlimited number.
Q: What operating system is the scada running on (eg Windows NT, Unix etc)?
A: NT, to be upgraded to Windows 2000 in a month or two.
Q: What impressed you most about the architecture? Open standards, wide range of drivers, the ability to upgrade, etc? Please elaborate.
A: The system is easily upgradeable, expandable and versatile. It has a network capability with peer-to-peer communication. There is a built-in store and forward capability; TCP-IP connectivity; it is IP addressable and has multi protocol capability. Other advantages include:
* Multitransport media (radio/fibre-optic/modem/satellite).
* From small to large I/O capability.
* Dual redundancy CPU option.
* Remote monitoring and programming capability, which saves on engineering and maintenance costs.
* Surge detection of the highest degree.
* Large memory capacity.
* Time tagging facility, 1 ms resolution.
Q: Is the system integrated onto an intranet or the Internet? If so, does the configuration allow simple remote monitoring, or is it configured to allow full remote control? If not, what level of intranet/Internet control does the scada allow for future use?
A: Currently one station, Durban Verulam, is viewable on the Internet. The system is fully expandable.
Q: What sort of redundancy is built into the system?
A: Dual CPU redundancy.
Graphics
Q: Describe the graphics development process - eg did you use standard library images, or did you have to draw images from scratch?
A: This was done from a mix of standard library images and images created from scratch.
Q: Did you use any 'special' images (eg embedded video clips, photographs, 3D images etc)?
A: No.
Compatibility
Q: Did you run the scada in conjunction with any third-party application software? Describe.
A: Included but not used.
Q: Does the scada allow for the user to create scripts to perform specific tasks? Describe any specific scripts that were written for this project.
A: Included but not used.
Management reporting
Q: Is a trending and historical data reporting system included? Please elaborate.
A: Yes, on all analog tags. There is a 30 days archive and a cyclic buffer.
Q: Management reporting system?
A: Included but not used.
Q: MES integration?
A: No - the system is used to monitor trends and the requirements of gas.
Q: Is a management reporting system included in the package?
A: Not yet implemented - possible future requirement.
Q: Was any additional software development needed? Please elaborate.
A: All standard.
Conclusion
Q: What impressed you the most about the system?
A: The remote diagnostic and upgrade facilities impressed the most. The total reliability of the system was its most predominant feature.
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