Are you looking for a job change? Are you prepared in attending an interview? Are you worried for job interview preparation? Then do not worry, we’ve a right answer for your job interview preparation. If you are preparing for DCS (distributed Control System) job interview and don’t know how to crack interview and what level or difficulty of questions to be asked in job interviews then go through Wisdomjobs DCS interview questions and answers page to crack your job interview. DCS is a centrally operated control system where large number of control loops where in self run controllers are spread across the system. Below are the frequently asked DCS (distributed Control System) interview questions and answers which can make you feel comfortable to face the interviews:
Question 1. What Is A Distributed Control System ?
Answer :
A distributed control system (DCS) is a computerised control system for a process or plant, in which autonomous controllers are distributed throughout the system, but there is central operator supervisory control.
Answer :
This can be typically achieved by two ways:
By connecting o/p of one I/P converter to two positioners adjusted suitably for split range operation of control valves.
Taking two AO from DCS. Split range to be defined in DCS. Both I/P converters and positioners to be calibrated with input as 4to20 ma dc and 3to15 psi respectively.
Question 3. What If Thermocouple Wire Is Opened In The Field? What Signal Goes To Dcs?
Answer :In most modern instruments the signal may be programmed to go to either maximum or minimum depending upon end user’s requirement.
Answer :Usually there is a blocking diode to protect the transmitter against supply reversal and almost zero current signal should be transmitted.
Question 5. What Is The Difference Between A Hart Patch Card And A Field Terminal Assembly?
Answer :A field terminal assembly is a DCS component where field signals are terminated. In a DCS using analog transmitter signals but smart remotely configured transmitters field signals from barriers are first brought to a HART patch panel. From here the analog signals are wired to the DCS field termination assembly or I/O card. The digital signals are wired to the HART multiplexes who extract the digital information and provide two way communication path between smart instruments and a computer running suitable software.
Question 6. What Is The Difference Between Dcs And Plc?
Answer :
Distributed control system(DCS) and Programmable logic controller. These are the control systems which handles fields I/Os. Basic difference between DCS & PLC is
Question 7. When Proportional, Integral And Derivative (pid) Controller Is Used?
Answer :
PID controller is used when system requires:
Question 8. When Proportional (p) Controller Is Used ?
Answer :
Proportional (P) Controller is used during the following conditions:
Question 9. When Proportional (p) Controller Is Used ?
Answer :
Proportional (P) Controller is used during the following conditions:
Question 10. When Integral (i) Controller Is Used ?
Answer :
Integral (I) controller is used during:
Question 11. When Derivative (d) Controller Is Used ?
Answer :
Question 12. When Proportional Plus Integral (pi) Controller Is Used
Answer :
Proportional and Integral action is employed when
Question 13. When Proportional And Derivative (pd) Controller Is Used ?
Answer :
PD action is employed when:
Question 14. What Are The Basic Elements Of Distributed Control System?
Answer :
Basic Elements of Distributed Control System :
Distributed Control System continuously interacts with the processes in process control applications ones it gets instruction from the operator. It also facilitates to variable set points and opening and closing of valves for manual control by the operator. Its human machine interface (HMI), face plates and trend display gives the effective monitoring of industrial processes.
Question 15. Explain Open Loop Control System ?
Answer :
Control System in which output quantity has no effect on the input quantity is called Open Loop Control System. Open Loop Control System has no facility to correct automatically the error generated in the output. From output of the system no feedback is given back to the input for correction. In Open loop control system the output can be varied by varying the input. But due the external disturbance system output may change. Any variation in the output from the desired once again attained by varying the inputs manually.
Question 16. What Are The Advantages And Disadvantages Of Open Loop Control System ?
Answer :
Advantages:
Disadvantages:
Question 17. Explain Closed Loop Control System ?
Answer :
Control system in which the output has an effect on the input quantity in such a manner that the input quantity will adjust itself based on the output generated is called Closed loop Control System. Open loop control system can be modified in to closed loop control system by providing a feedback. This feedback automatically corrects the changes in the output due to external disturbance. Hence closed loop control system is called automatic control system.
Question 18. What Are The Advantages And Disadvantages Of Closed Loop Control System ?
Answer :
Advantages:
Disadvantages:
Answer :
Differential inputs provide better common mode rejection and signal-to-noise ratio.
Question 20. What Is Ground Loop? Preventive Steps To Avoid Ground Loop?
Answer :
When ground wiring is not done properly, grounding of various points is not effective and potential differences exist between them resulting in currents flowing between them. This leads to measurement errors and is not desirable. It can be eliminated by proper ground wiring.
Answer :
Control valves must be installed as per direction marking provided by the manufacturers or instruction manuals. Though people tend to generalize, this is often misleading.
Question 22. How Control Loop Should Be Tuned In Process Loop?
Answer :
You may use Ziegler-Nichol’s method ( open loop / closed loop ) or special tuning software tools.
DCS(distributed control system) Related Tutorials |
---|
DB2 Using SQL Tutorial |
DCS(distributed control system) Related Practice Tests |
|
---|---|
PL/SQL Practice Tests | DB2 Using SQL Practice Tests |
Programmable Logic Controller (PLC) Practice Tests | Variable Frequency Drive(VFD) Practice Tests |
DCS(distributed control system) Practice Tests | PowerShell Practice Tests |
Dcs(distributed Control System) Practice Test
All rights reserved © 2020 Wisdom IT Services India Pvt. Ltd
Wisdomjobs.com is one of the best job search sites in India.