Manganese Metal Company (MMC) is the world’s largest producer of pure electrolytic manganese metal. It produces only selenium-free electrolytic manganese – the purest form – to meet the specialised needs of its customers around the world. The production facility is located in Nelspruit, in the Mpumalanga province of South Africa. Manganese Metal is manufactured using the process of electroplating and MMC has been using the Adroit SCADA since upgrading its legacy control system in 2000.
Operations at MMC is currently controlled via 12 SCADA machines each connected to a Programmable Logic Controller (PLC) varying from old Modicon 984’s to the latest Telemecanique Premium PLCs. The PLCs are all stand alone but the 12 SCADA machines are connected via an office network.
All machines and PLCs are powered using UPS power and can run independent from any network connection. The SCADA machines are used as a the Human Machine Interface (HMI) in a supervisory role with all critical process control being carried out on the PLCs. The system is designed that the plant can run without the SCADA for short periods. Licensing ranges from a small 75-scan point application up to 1,500 scan points . Adroit supplied an all-inclusive package, which includes free licensing and package upgrades. Aftersales-support is done telephonically or by using email which is sufficient in 99 per cent of cases. In extreme instances Adroit has sent down a support technician for on site assistance.
The biggest application at MMC is on a 1,500 scan point Hasp with a total of 1,136 scan points used. These scan points include all digital and analog points and some of these points are manipulated in different ways such as expressions and marshalling. This specific machine is connected to a Modicon 984 and a Spectrum Teleranger with two remote stations. Updates per day are recorded in the archive once a day at 4pm. This scheduled backup is run on a server machine maintained by the IT department for all 12 SCADA machines. This updates all changes made during the day on any machine.
In terms of the intranet, all the SCADA mimics are available on the intranet for remote viewing on all office machines if remote view was installed on the specific PC, this is done by a controlled application form only. Full remote control is selectable as an option but for plant safety reasons it is not used at MMC.
The wide range of graphic images (wizards) saved a lot of development time for the developers and can even be changed according to site requirements. During the design process of each new SCADA application, consideration was given to re-usable objects and standards were implemented throughout the project. All mimics were developed as true replicas of the plant, this made the adoption by and training of operations staff very easy.
At MMC control parameters are very important and precision control is done by using and MS SQL database and Excel to write and read from and into tags. Control parameters derived from analysers can be read into Adroit and then into the PLC. This option can be used or the operator can select to normal PLC set point control.
Trending and historical data is a very nice feature of Adroit and historical data for up to 35 days is set as standard at MMC. Any trend point can be selected and exported onto an Excel spreadsheet or can be viewed in the historical mode, the trend lines are static, reflecting the values obtained from the current data log file. Different views of an historical trend line may be selected by resetting the time period, or by zooming in. Alarming is a feature that can easily fail in its usefulness if not managed properly and only alarmed tags of real importance to the operations are used. Alarms have further been rated on their importance and are displayed in different colours to highlight their importance to the operator. A modem from Adroit was installed on a trial basis on one of the critical SCADA machines, this modem assists in managing alarms. Critical alarms send SMSs to pre-programmed cell numbers.
Henk van der Westhuizen of MMC, comments: “Adroit is a very complete system, it complies with all the requirements needed on our specific plant and specifically the VCR feature is very handy in supplying needed data to all stakeholders. Adroit is a South African company and their willingness in assisting in special applications made them a sure choice for our company. Another feature from Adroit is their new versions that we get on our agreement with them. These versions contain new features that we did not think of previously and with this development of the product we are sure of a long term relationship with Adroit.”