Over 5000 process tags are archived. In order to view the data, over 950 graphical trends of the quantities displayed in curves, that can be viewed by up to 85 COMES users within the plant IT network, are configured.
Processing the process quantities
Trends
Each process quantity is specified by:
- Tag name (process quantity), based on which the curve is established
- Source (database) of the signal
- Curve description and color, scaling of time and quantity axes
- Sampling time
The course of the process quantity is shown as a curve in the trend screen. Any number of curves may be assigned to the trend. Trends may be viewed as historical or real-time ones. Quantities are sampled with a time stamp with the accuracy of milliseconds and, besides the value itself, they contain also the quality of a sample. Time stamps of tags and alarms are stored in UTC (Universal Time Coordinated) time on the server. The users are shown the values in their local time. It is possible to change the value range of axes or shift axes of the displayed chart. The user is allowed to change the scale of the trend by zooming it using the mouse wheel, switch on/off the “on-line” view of the trend. Using the target cross, it is possible to read out values of the curve within the area selected, their time stamps and differences. The user can shade the course of the curve, when the technological quantity exceeds limit values, or on changes in daylight saving time.
Technologists can make use of a function for comparing curves within various time periods, e.g. courses of technological quantities of two batches. COMES Historian offers the technologist an easy-to-use tool for optimizing the technological process.
An interesting example of use is a development of medicinal API substances with validation production batches, the optimization of which is worked on by a team of experts residing in the USA and those in CZ. Thanks to the COMES Historian both teams may analyze progress of batches through the process quantities without having to be present on the site.
Reports on alarms of control systems
Alarms, or reports, are important part of the administration of controlled processes, because they advise the keeper of the state of the process. Alarms are usually classified according to various criteria, nevertheless the most important criterion is the level of urgency which tells the operator how quickly he is to respond to the situation. As for the urgency, the alarms are divided into several levels from informative alarms of lowest priority of urgency via warnings up to the highly urgent alarms which should be dealt with as quickly possible because they may end up in an accident. Typical examples of the urgent alarms are alarms on exceeding permissible tolerances of process quantities, such as pressure, temperature, level, position and others, the urgency of which is, apart from textual information, usually highlighted with color, flashing of objects on the screens of the control rooms pulpits or by site beacons e.g. acoustically – hooters and buzzers, or by sending the message to appointed workers onto their mobile devices. The alarms are generated by the control systems and bear usually, along with the message, another criteria for the user to sort them out. This is typically the date and time of the alarm coming in and out, location, text information for the user, design marking of the quantity and others. In case of specific processes the alarms may carry special information, e.g. production or batch step number.
Use of alarms by the operators to control quality and maintenance of the technology
Alarms may be used by various groups of users, first of all, the operators in process control rooms, that have to ensure that the process stays under control and is optimally controlled free of emergencies and accidents. Another users of production processes are technologists and production people whom the alarms show deviations from a standard progress. Some of the alarms may need to be analyzed and used to correct process or explain the deviation by making comment on it in production documentation. Alarms are made use of by quality assurance (QA) which checks on every limit being exceeded or occurrences of nonconformities during batch production.
Among special groups of those who use and analyze alarms are maintenance staff, who use alarms in case of both an immediate repair of the device and a long-term evaluation of the state of the technological equipment. A system offering both the processing of critical alarms (delivered also onto the mobile devices) and the analysis of historical information stored in database systems for evaluation of a wear, quality of different kinds of instruments, etc., may be suitable for the service actions.
Effective work with alarms
In order to make working with the alarms effective, it is necessary to provide the groups of users with a powerful system for alarm processing. Operators may be happy with the functions built in the individual control systems, but the others may find these functions inconvenient for various reasons (the location in the control room away from the user’s workplace, additional terminals may be very costly, control systems functions may not include sorting, searching, statistics, copying to documents etc.). Another problem is a typical situation with larger processes controlled by more than one control system, very often supplied by different suppliers. In this case, other users, who need central processing of alarms, may be unable to work at all. Because of the above reasons, COMES Historian is used as the alarm processor providing various groups of users with associated functions needed for their productive work.