Recent questions tagged control-systems

Description : Frequency Domain Analysis in Control System

Last Answer : Frequency Response: The Frequency Response of the system is the steady state response of the system obtained as the output when a sinusoidal input signal is given to the system. For determining the ... of the system, adjust the gain of the control system and helps in designing the control system.

Description : Advantages of Frequency Domain Analysis

Last Answer : Advantages of Frequency Domain Analysis Frequency Response Analysis: In frequency response analysis the input to the control system is fed with a sinusoidal signal with different frequencies. The output ... system Frequency domain analysis can also be carried out for the non linear control systems.

Description : PI Controllers in Process System

Last Answer : PI controllers are used in many industrial control applications. The main purpose of using Proportional and Integral (PI) in process system is to improve the steady state accuracy of the ... requires higher values of the proportional and integral gains compared to gains required in PI controllers

Description : What is Zero of the system?

Last Answer : Zero of a function F(s) is a value at which the function F(s) becomes zero, where F(s) is a function of complex variable s.

Description : What is Pole of the system?

Last Answer : Pole of a function F(s) is the value at which the function F(s) becomes infinite, where F(s) is a function of the complex variable s.

Description : What are Test signals and their significance?

Last Answer : The knowledge of the input signal is required to predict the response of the system. In most of the systems input signals are not known ahead of the time and it is also difficult to ... the control system. The commonly used test signals are impulse, ramp, step signals and sinusoidal signals.

Description : How Time response of the system is divided?

Last Answer : Time response of the system consists of two parts: 1.Transient state response 2. Steady state response. Transient response of the system explains about the response of the system when the input ... other. Steady state response of the system shows the response as the time t, approaches infinity

Description : What is Time response of the control system?

Last Answer : Time response of the control system is defined as the output of the closed loop system as a function of time. Time response of the system can be obtained by solving the differential equations governing the system or time response of the system can also be obtained by transfer function of the system.

Description : What is Order of the system?

Last Answer : Order of the system is defined as the order of the differential equation governing the system. Order of the system can be determined from the transfer function of the system. Also the order of ... function. For nth order system for a particular transfer function contains 'n' number of poles.

Description : Explain Mechanical Translational System?

Last Answer : Model of mechanical translational system can be obtained by using three basic elements Mass, Spring and Dash-pot. Weight the mechanical system is represented by mass and is assumed to be ... represented by the spring Friction existing in a mechanical system can be represented by dash-pot.

Description : What is mathematical model of a control system?

Last Answer : Control system is a collection of physical elements connected together to serve an objective. The output and input relations of various physical system are governed by differential equations. ... the system can be studied by solving the differential equations for various input conditions.

Description : What are the basic properties of Signal Flow Graph?

Last Answer : The basic properties of the signal flow graph are: Signal Flow Graphs are applicable to linear systems It consists of nodes and branches. A node is a point representing a variable or signal. A ... the gain of the branch The algebraic equations must be in the form of cause and effect relationship

Description : What is S-domain and its significance?

Last Answer : By taking Laplace transform for differential equation in the time domain equations in S-domain can be obtained. L{F(t)}=F(s) S domain is used for solving the time domain differential equations easily by applying the Laplace for the differential equations.

Description : What is Signal Flow Graph?

Last Answer : A Signal Flow Graph is a diagram that represents a set of simultaneous linear algebraic equations. By taking Laplace transform the time domain differential equations governing a control system can be ... s-domain. The signal Flow graph of the system can be constructed using these equations.

Description : Where Servomechanism is used?

Last Answer : Servomechanism is used in control system where the output is pertained to vary the mechanical position of a device. Servo Mechanism is widely used in Governor value position control mechanism ... controls using power Thyristors. Servomechanism is also widely used in the robotic hand movements.

Description : What is the basic rule for Block Diagram Reduction Technique?

Last Answer : The rules of the Block Diagram reduction Techniques are designed in such a manner that any modifications made in the diagram will not alter the input and output relation of the system

Description : What is Time Invariant system?

Last Answer : Time Invariant System is one in which the input and output characteristics of the system does not change with time.

Description : Define Transfer Function?

Last Answer : Transfer Function of a control system is defined as: i) Ratio of Laplace transform of Output to the Laplace transform of the Input with zero initial conditions ii) Transfer function is defined as the Laplace transform of Impulse response of the system with zero initial conditions

Description : What are the basic components of the feedback control system?

Last Answer : Basic components of the feedback control system are process system (open loop system), feedback path element, error detector, and controller.

Description : What are the Characteristics of Negative Feedback?

Last Answer : Negative Feedback in a Control System has following Characteristics Reduction in the gain at the expense of better stability of the system Rejection of disturbance signals in the system Low Sensitivity to parameter variations Accuracy in tracking the steady state value

Description : What is the effect of positive feedback on stability of the system?

Last Answer : Positive feedback is not used generally in the control system because it increases the error signal and drives the system to instability. But positive feedbacks are used in minor loop control systems to amplify certain internal signals and parameters

Description : Why Negative Feedback is preferred in the Control System?

Last Answer : The role of Feedback in control system is to take the sampled output back to the input and compare output signal with input signal for error ( deviation from the desired result). ... and is less sensitive to the parameter variations. Hence in control systems negative feedback is considered.

Description : What is a feedback in Control System?

Last Answer : The Feedback in Control System in one in which the output is sampled and proportional signal is fed back to the input for automatic correction of the error ( any change in desired output) for futher processing to get back the desired output.

Description : What are different types of Control Systems?

Last Answer : Two major types of Control Systems are 1) Open loop Control System 2) Closed Loop Control Systems Open loop Control Systems: The Open loop Control System is one in which the Output Quantity has ... quantity to the input quantity for the correction so as to maintain the desired output of the system.

Description : What is Control System?

Last Answer : In a System the output and inputs are interrelated in such a manner that the output quantity or variable is controlled by input quantity, then such a system is called Control System. The ... is called controlled variable or response and the input quantity is called command signal or excitation.

Description : What is a System?

Last Answer : When a number of elements or components are connected in a sequence to perform a specific function, the group of elements that all constitute a System

Description : Closed loop and Open loop Control System Advantages and Disadvantages

Last Answer : Open Loop Control System: 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 ... in the closed loop system and more care is needed to design a stable closed loop system

Description : Phase Margin?

Last Answer : Answer: The phase margin is the amount of additional phase lag at the gain cross over frequency required to bring the system to the verge of instability.

Description : What is Gain Margin?

Last Answer : Answer: The Gain Margin is defined as the reciprocal of the magnitude of open loop transfer function at phase cross over frequency. The gain margin indicates the amount by which the gain of the system can be increased without affecting the stability of the system

Description : What is Phase cross over frequency?

Last Answer : Answer: The frequency at which the phase of the open loop transfer function is 180o is called the phase cross over frequency.

Description : What is Cut-off rate?

Last Answer : Answer: The slope of the log-magnitude curve near the cut-off frequency is called the cut-off rate. The cut-off rate indicates the ability of the system to distinguish between the signal and the noise

Description : What is Resonant Frequency?

Last Answer : Answer: The frequency at which resonant peak occurs is called the resonant frequency. Resonance frequency explains about the speed of the transient response.

Description : What is Resonant peak?

Last Answer : Answer: Resonant peak is defined as the maximum value of the closed loop transfer function.A large resonant peak corresponds to large overshoot in the transient respose

Description : Distributed Control System (DCS) in Power Plant

Last Answer : Usage of Single Computer for control of all the process variables of plant would result in the loss of control action in the plant if failure occurs to the master single computer. Also, ... control loop This type of distribution results in increase in speed and reliability of the control system.

Description : Why are two plugs provided on a D.P transmitter? 

Last Answer : 1.The top plug is a vent plug for venting the air entrapped inside the cell. 2.The bottom plug is a drain plug for draining the liquid accumulated inside the cell.  

Description : What is positive Displacement meters ? 

Last Answer : principle: The principle of measurement is that as the liquid flows through the meter it moves a measuring element which seals off the measuring chamber into a series of measuring compartments each holding a definite ... type. 5. Sliding vane type. 6. Rotating vane type. 7. Oval Gear type.  

Description : How would you choose differential range ?

Last Answer : The most common diff. range for liquid measurement is 0-100" H2O. This range is high enough to minimize the errors caused by unequal heads in the seal chambers, differences in temps. of load lines etc. ... up to 400" and a decrease down up to 20" by merely changing range tubes or range adjustments. 

Description : What is Reynolds number ?

Last Answer : Dynamic similarity implies a correspondence of fluid forces in two systems. In general situation there are many classes of forces that influence the behavior of fluids. Some of these are ... , many of the deviation from the theoretical equations are called Reynaldo number effects.   

Description : Where is a quadrant orifice used ? 

Last Answer : If the fluid is viscous and the operating Reynolds number is low quadrant orifice is preferred  

Description : Explain the working of a target meter.

Last Answer : The target meter combines in a single unit both a primary element and a force balance flow rate transmitter. A circular disc (or target) supported concentrically in the pipe carrying ... require elevated temperatures to avoid solidification, this elimination of liquid connection is useful.   

Description : Where is the integral orifice used ?

Last Answer : Integral orifice is used to measure small flow rates. It is mounted directly on the secondary device. The integral orifice diameter varies between 0.020 inch and 0.250 inch diameter. The integral orifice finds considerable use in laboratory and pitot plants. Calculation of flow rate :

Description : Explain the working of a Pitot tube. 

Last Answer : The pitot tube measures the velocity at point in the conduct. If quantity rate measurement is desired, it must be calculated from the ratio of average velocity to the velocity at the point of measurement. ... will be a measure of the impact pressure and therefore of the velocity of the stream oil.  

Description : Explain the working of a turbine meter. 

Last Answer : Turbine meters consist of a straight flow tube within which a turbine or fan is free to rotate, about its axis which is fixed along the center line of the tube. Straightening vanes ... to flow rate. Turbine meter are primarily applied to measurement of clean and non-corrosive hydrocarbons.  

Description : Explain the working of a magnetic meter.

Last Answer : An electric potential is developed when a conductor is moved across the magnetic field. In most electrical machinery the conductor is a "wire"; the principle is equally applicable to a moving, electrically ... , since there are no location for solids to collect except the walls of the tube itself.

Description : What are De-saturators ?

Last Answer : When, in some processes, e.g. batch process, long transient responses are expected during which a sustained deviation is present the controller integral action continuously drives the output to a minimum ... . This phenomenon is called "integral saturation of the control unit". When this condition. 

Description : What is an anti reset wind up ? 

Last Answer : If the limit acts in the feed back section of the control amplifiers integral circuit, the controller output will immediately begin to drive in the opposite direction as soon as the process signal crosses the set point. This approach is referred to as antireset wind up. 

Description : Explain the working of an electronic P.I.D. controller. 

Last Answer : Input from the measurement transmitter is compared with the set point voltage to produce a deviation signal. The deviation signal is combined with a characterized feed back signal to ... controlled by value of derivative resister. This resister is variable and constitutes derivative adjustment. 

Description : Explain tuning of controllers. 

Last Answer : Tuning basically involves adjustment of proportional. Integral and derivative parameters to achieve good control. The gain, time constants, and dead times around the loop will dictate the settings of ... the controller output to its previous value and return the controller to auto operation.   

Description : What is reset-wind up?

Last Answer : When reset action is applied in controllers Where the measurement is away from the set point for long periods the rest may drive the output to its maximum resulting in rest wind up. When the ... can be avoid by including anti-reset wind up circuit which eliminates the problem of output saturation. 

Description : Where is on off control used ?

Last Answer : On off control is used when ١. Precise control is not needed. ٢. Processes that have sufficient capacity to allow the final operator to keep up with the measurement cycle. ٣. It is mainly used in refrigeration and are conditioning systems.