In the Process Industries

The first computer control system went on line in an industrial plant in 1959. Since then, there have been remarkable advances in processing and transmitting information electronically. Developments in the technology of digital hardware, software, basic sensors and all forms of communication offer the potential for industrial control systems that are highly automated and provide improved operating performance.

The earliest applications of computer control were in the process industries. The process industries are those which change the composition of materials to produce metals of higher value. Here automation is in some ways easier, and is fully developed. In process industries instruments are available to monitor the continuous flow of a product and to send the data to the computer, which can then direct changes in the process by adjusting¹ valves and switches.

The elements of a control system have the important functions of measurement, control, actuation and communication. Measurement refers to the sensing of variables such as flow rate, temperature, pressure, level, and chemical composition, and the transmission of the measurement to the controller. Control is the decision-making operation. It compares the measured state of the process with the desired conditions and decides how the variables should be manipulated. Actuation is the means by which the operating variables are manipulated. Typical actuators are valves, rheostats, switches and relays. Communication includes the display of information to the plant operators as well as the transmission of important variables to the plant management.

The organization of a plant control system is comprised at different levels. The lowest level is occupied by the control computer that regulates a single process unit² holding it to desired operating conditions and moving the unit to a safe condition in emergencies³. The next step is a supervisory⁴ computer responsible for coordinating several units, for scheduling operations, and for optimizing the plant's performance. At the top level is the manager control computer, which supplies the manager with current information about manufacturing operations.

Improved communications are making it possible to use systems in which elements of the control system are located throughout the plant and communicate with each other through networks. Communication over these networks is by a digital signal.

Notes:

¹ to adjust – манипулировать

² process unit – технологическая установка

³ in emergencies – при чрезвычайных обстоятельствах

⁴ supervisory – управляющий

1. Translate the title of the text.

2. Formulate the main idea of the text.

3. Choose the main information from every paragraph.

4. Make up the plan of the text.

5. Write down the annotation of the text in Russian.

Unit 8 From cad/cam to cim

Vocabulary

1. trend – общее направление, тенденция

2. computer-aided design(CAD) – система автоматизированного проектирования(САПР)

3. computer-aided manufacturing(CAM) – автоматизированная система управления производством, технологическими процессами (АСУП, АСУТП)

4. scope – размах, охват

5. to extend – простирать(ся)

6. comprehensive – обширный; всесторонний

7. computer-integrated manufacturing(CIM) – производство с комплексным управлением от ЭВМ

8. circuit – схема, цепь

9. to draft – делать чертёж; проектировать

drafting board – чертёжная доска

10. to invoke – вызывать; активизировать(процедуру)

11. to draw – чертить; рисовать

drawing – чертёж; рисунок

12. to entail – влечь за собой; вызывать

13. to support – поддерживать; способствовать, содействовать

14. numerical control (NC) – числовое программное управление(ЧПУ)

15. to schedule – назначать, намечать; планировать; составлять график (расписание)

scheduling – оперативное управление; планирование

16. customer – заказчик; клиент

17. order – заказ

18. shipment – погрузка; отправка

19. activity – деятельность