Showing posts from September, 2021

Automotive Driverless train driving

  Automotive Driverless train driving The automotive Automotive Driverless train driving system is one of the recent technologies used in train travel systems. Basically, this system means that the train will run without drivers. It is guided by LIDAR (Light Detection and Ranging) technology. It is a remote sensing method that uses light in the form of pulsed radar to measure ranges. It has various optical sensors and other types of laser-guided instruments which makes the vehicle to move automatically over a designated path. They run on a virtual or marked track and are monitored by a central control system like SCADA or DCS. Advanced levels of programming are done which ensures that the train follows its path without the need of a driver. This also automatically reduces the number of errors. This ensures that the safety and reliability of the system are maintained in a proper way. Just like an automated guided vehicle used in factories that run without drivers and on marked trains, a

Dead time Multiple Choice Questions

  Dead time Multiple Choice Questions 1. Dead time of the instrument is a) The time required by an instrument for initial warming up b) The time required by an instrument to begin to respond to a change in the measured value c) The largest change of input quantity for which there is no output of the instrument d) None of the above Answer: The time required by an instrument to begin to respond to a change in the measured value 2. The dead time of an instrument refers to _____ a) Large change of input quantity for which there is no output. b) The time encountered when the instrument has to wait for some reactions to take place. c) The time before the instrument begins to response after the quantity has altered. d) Retardation or delay in the response of an instrument to a change in the input signal. Answer: The time before the instrument begins to response after the quantity has altered.

Electric actuators

  Electric actuators Electric actuators are motor driven devices that utilize an electrical input signal to generate a motor shaft rotation. This rotation is, in turn, translated by the unit’s linkage into a linear motion,which drives the valve stem and plug assembly for flow modulation. In case of electric signal failure, these actuators can be specified to fail in the stem-out, stem-in, or last position. Commonly used motors for electric actuators include steppers and servos.  steppers A step motor uses gears with increments in the range of 5,000 to 10,000 at 90 degree rotation for accurate positioning at lower speeds. The disadvantage is that steppers may lose synchronization with the controller when employed in an open loop without an encoder or if they are undersized for an application.  servos Servos, by definition, are closed loop and provide superior performance at high speeds, but at a higher cost. High precision screws and anti-backlash mechanics provide accuracies to ten-tho

Process Control Multiple Choice Questions

  Process Control Multiple Choice Questions 1. When we adjust integral time in a controller a) We determine an RC time constant in the controller’s internal feedback path b) We adjust the time it will take for integral to equal derivative c) We set the process time constant so that it will always equal 1 d) What happens specifically depends on the type of controller, pneumatic Answer: We determine an RC time constant in the controller’s internal feedback path 2. For proper feedback in a process control element, it is required to ________ a) measure P b) measure set point c) measure error d) measure comparator Answer: measure P 3. If in a proportional-plus-integral controller measurements away from the set point for a long period, the controller’s output will be a) 0 b) Unknown c) 0 d) 100 percent Answer: 0 4. In the modem controller, derivative action is applied only to the a) Error b) Measurement c) Setpoint d) Integral circuit Answer: Measurement 5. What is the main objective of proc

Pneumatic actuators

  Pneumatic actuators Pneumatic actuators utilize an air signal from an external control device to create a control action via a solenoid. These are commonly available in two main forms Piston actuators Diaphragm actuators Piston actuators Piston actuators are generally used where the stroke of a diaphragm actuator would be too short or the thrust is too small. The compressed air is applied to a solid piston contained within a solid cylinder. Piston actuators can be single acting or double acting, can withstand higher input pressures, and can offer smaller cylinder volumes which can act at high speed. Diaphragm actuators Diaphragm actuators have compressed air applied to a flexible membrane called the diaphragm. These types of actuators are single acting, in that air is only supplied to one side of the diaphragm, and they can be either direct acting (spring-to-retract) or reverse acting (spring-to-extend).  Advantages of Pneumatic Actuators The biggest advantage of the pneumatic actuat


  Actuators   A valve actuator is a device that produces force to open or close the valve utilizing a power source. This source of power can be manual (hand, gear, chain-wheel, lever, etc.) or can be electric, hydraulic or pneumatic. Basic actuators turn valves to either fully opened or fully closed positions. But modern actuators have much more advanced capabilities. They not only act as devices for opening  and closing valves, but also provide intermediate position with high degree of accuracy. The valve actuator can be packaged together with logic control and digital communication ability to allow remote operation as well as allowing predictive maintenance data. Type of Actuators   Pneumatic actuator Electric actuator Pneumatic actuator Pneumatic actuators utilize an air signal from an external control device to create a control action via a solenoid. These are commonly available in two main forms Piston actuators Diaphragm actuators. Electric actuator Electric actuators are motor d

Gate Valves

  Gate Valves Gate valves use linear type of stem motion for opening and closing of a valve. These valves use parallel or wedge shaped discs as closure members that provide tight sealing. Gate valves are a common valve type used for basic on/off service. Manual Gate Valves are operated with a simple hand wheel that causes the stem and gate to rise. When closed, the gate seats against a seat ring, both of which have a special treatment to provide reliable shut-off. Advantages High capacity  Tight shutoff  Low cost  Little resistance to flow  Ability to cut through slurries, scale and surface build-ups Provide unobstructed flow paths that not only provide high flow capacity (Cv), but  even allows slurry, large objects, rocks and items routinely found in mining processes to safely pass through the valve.  Disadvantages Poor control  Cavitate at low pressure drops  Cannot be used for throttling Relatively low pressure limitation - general pressure limitations are 150 psi at maximum.  Uses

Globe Valves

 Globe Valves Globe valves consist of a movable disk-type element and a stationary ring seat in a generally spherical body. The valve stem moves a globe plug relative to the valve seat. The globe plug can be at any position between fully opened and fully closed to control flow through the valve. The globe and seat construction gives the valve good flow regulation characteristics. Turbulent flow past the seat and plug, when the valve is open, results in a relatively high pressure drop, limited flow capacity, and low recovery. Advantages Efficient and precise throttling  Accurate flow control  Disadvantages Low recovery and relatively low coefficient of flow (Cv).  High pressure drop, higher pump capacity and system wear  More expensive than other valves The sealing device is a plug that offers limited shut-off capabilities, not always meeting bubble tight requirements. Applications requiring Precise flow regulation Frequent and wide throttling operation  Suited to very high pressure dro

Control Of Air To Fuel Ratio

  Control Of Air To Fuel Ratio The fuel/air ratio is the lowest if excess air level (measure in percent of oxygen 02) is present in the flue gas at a set firing rate without the carbon monoxide (CO) being produced. At low firing rates; the burner design requires more excess air to ensure the mixing of air with the fuel in proper ratio. At higher firing rates there is enough differential pressure drop (burner wind box to combustion chamber area) for the air to mix with the fuel. All boilers have a fuel/air ratio curve and it is extremely important that the plant has this documented information. In other words ratio control is adopted to maintain the air fuel ratio. The air to fuel ratio is the proportion of air to fuel supplied during combustion process. The optimal ratio (the stoichiometric ratio) occurs when all the fuel and oxygen in the reaction chamber balance each other perfectly. Rich burning occurs when there is more fuel than air in the combustion chamber while lean burning occ

Five-layer IoT Architecture

  Five-layer IoT Architecture Another architecture which is five-layers IoT architecture is proposed by the researchers who were worked on IoT. In this five-layer IoT architecture, the three-layers which are the application, network, and perception layers are having same architecture like three-layer IoT architecture. Additionally, the Business layer, Transport layer, and processing layer are the new one. Business Layer Application Layer Processing Layer Transport Layer Perception Layer Business Layer: This layer is the head of the IoT architecture. It manages the complete IoT system even applications, user’s privacy, profit models, etc. Application Layer: This layer is to deliver the specific application to the end-user. The specific applications can be done with this application layer. Example of this layer like a smartphone, smartwatch,  smart TV, etc. which is used for a specific application. Processing Layer: It is in the middle of the IoT architecture. It’s having an important ro

IoT Protocol Architecture

  IoT Protocol Architecture The most interesting point here is, IoT has don’t have any particular architecture. The researchers proposed different IoT architectures. But in that most proposed architectures three-layer architectures & five-layer architecture. Three-layer IoT Architecture This architecture introduced in the early days of research of IoT technology. The three-layers are in IoT architecture is for Application Layer Network Layer Perception Layer Application Layer: This layer is to deliver the specific application to the end-user. The specific applications can be done with this application layer. Example of this layer like a smartphone, smartwatch,  smart TV, etc. which is used for a specific application. Network Layer: Network layer have an important role in IoT architecture. It connects to the other smart electronic devices (smartwatches, servers, etc). The network layer is for transmitting and processing the sensor data. Perception Layer: It is the physical layer and

What is wireless charging?

  What is wireless charging? Wireless charging is a technology that charges devices without using connectors or metal contacts. This is also referred to as non-contact charging, non-contact power transmission, and wireless power supply. Wireless charging technology is attracting increased attention by eliminating the need for power cords when charging. This is expected to increase connector safety and resistance to dust and water while enabling multiple devices to be charged using a single charger.

Simple Low cost DC Motor Project

  Simple Low cost DC Motor Project 

Butterfly Valves Applications advantages and disadvantages

  Butterfly Valves Butterfly valves consist of a disc attached to a shaft with bearings used to facilitate rotation. These are considered high recovery valves, since only the disc obstructs the valve flow path. The flow capacity is relatively high and the pressure drop across the valve is relatively low. The butterfly valves are used for limited throttling where a tight shut off is not required. When fully open, the butterfly creates little turbulence or resistance to flow. Best Suited Control Linear Equal percentage  Recommended Uses Fully open/closed or throttling services Frequent operation Minimal fluid trapping in line Applications where small pressure drop is desired  Applicable Standards AWWA C504 for rubber-seated butterfly valves API 609 for lug and wafer type butterfly valves MSS SP-69 for general butterfly valves UL 1091 for safety butterfly valves for fire protection services  Advantages Low cost and maintenance High capacity  Good flow control Low pressure drop  Disadvanta

What Is A Circuit?

  What Is A Circuit? An electronic circuit is a circular path of conductors by which electric current can flow.  A closed circuit is like a circle because it starts and ends at the same point forming a complete loop. Furthermore, a closed circuit allows electricity to flow from the (+) power to the (-) ground uninterrupted. In contrast, if there is any break in the flow of electricity, this is known as an open circuit.

Ball Valves Applications

  Ball Valves Ball valves are a quick opening valves that give a tight shutoff. When fully open, a ball valve creates little turbulence or resistance to flow. The valve stem rotates a ball which contains an opening. The ball opening can be positioned in the fully open or fully closed position but must not be used to throttle flow as any abrasive wear to the ball will cause leakage when the valve is closed. Ball valves are considered high recovery valves, having a low pressure drop and relatively high flow capacity. Best Suited Control Quick opening Linear Recommended Uses Fully open/closed, limited-throttling Higher temperature fluids  Advantages Low cost  High flow capacity  High pressure/temperature capabilities Low leakage and maintenance  Tight sealing with low torque Easy quarter turn operation- desirable to most operators Fairly easy to automate.  Disadvantages Limited throttling characteristics  Prone to cavitation  Not suitable for slurry applications due to cavities around the

Low cost LDR sensor project without using Arduino

  Low cost LDR sensor project without using Arduino  

Top 40 Digital Signal Processing Objective Questions and Answers

  Top 40 Digital Signal Processing Objective Questions and Answers 1. DTFT is the representation of a) Periodic Discrete time signals b) Aperiodic Discrete time signals c) Aperiodic continuous signals d) Periodic continuous signals Answer: Aperiodic Discrete time signals 2. The interface between an analog signal and a digital processor is a) D/A converter b) A/D converter c) Modulator d) Demodulator Answer: A/D converter 3. The speech signal is obtained after a) Analog to digital conversion b) Digital to analog conversion c) Modulation d) Quantization Answer: Digital to analog conversion 4. x(n)=x(n-1)/4 with initial condition x(0)-1, gives the sequence a) x(n)= (1/4)^n b) x(n)= -(1/4)^n c) x(n)= (1/4)^-n d) x(n)= (-1/4)^-n Answer: x(n)= -(1/4)^n 5. For a system function H(s) to be stable a) The zeros lie in left half of the s plane b) The zeros lie in right half of the s plane c) The poles lie in left half of the s plane d) The poles lie in right half of the s plane Answer: The poles

Direct and Pilot Actuated

  Direct and Pilot Actuated In the direct-actuated type, the power unit (bellows, diaphragm, and so on) of the thermal actuator is directly connected to the valve plug and develops the force and travel necessary to fully open and close the valve. Direct-actuated regulators are generally simpler, lower in cost, and more truly proportional in action (with somewhat better stability). In the pilot-actuated design, the thermal actuator moves a pilot valve, internal or external. This pilot controls the amount of pressure energy from the control agent (fluid through valve) to a piston or diaphragm, which in turn develops power and thrust to position the main valve plug. The pilot may be internal or external. When external, independently acting multiple pilots are also available. Compared to direct-actuated TCVs, pilot-actuated regulators have smaller bulbs, faster response, and narrower proportional band, and they can handle higher pressures through the valve. Pilot-actuated regulators can al

Process Gain

  Process Gain The system function is the symbolic representation of how a process component changes its output in response to a change in its input. For example, if the system function is only a gain, only a constant (Kc, G, or some other symbol) would appear inside the block. The process gain is the ratio between the change in the output (dc) and the change in the input that caused it (dm). If the input (m) to the block is a sinusoidal, the output (c) will also be a sinusoidal.  The process gain can be the product of a steady-state gain (Kp) and a dynamic gain (gp) component. If the gain varies with the period of the input (exciting) sinusoidal, it iscalled dynamic gain (gp), while if it is unaffected by this period it is called steady-state gain (Kp). Therefore, if the process gain can be separated into steady-state and dynamic components, the system function can be given inside the block as (Kp)(gp).  The dynamic gain (gp) appears as a vector having a scalar component Gp and a phas

Control System Simulation

 Control System Simulation The simulation of instrumentation control systems includes measuring or detecting devices, the controllers, and the actuating or manipulating output elements. Most measuring devices may be simulated by one or more simple lags for dynamic representation, with added nonlinearities for device characteristics, sensitivity, or operating point modeling. For special functions, such as logarithmic input–output relationships (such as pH measurements), the general-purpose function-generating units may be used or the functions generated by implicit techniques.  the measuring device puts out a discontinuous (pulse-type) signal, signal-generating circuits may be used, as discussed later in this section.

Hybrid Computers

  Hybrid Computers A hybrid computer is a combination in hardware and software of one or more analog and digital computers. It aims at providing faster, more efficient, and more economical computational power than is available with computers of either type alone. The results depend to a large extent on the exchange of information between the analog and the digital computers and on the compatibility in operations and mutual interactions between the two parts. A hybrid computer provides for the rapid exchange of information between the parallel and simultaneous computations and simulations within the analog computer and the serial and sequential operations of the digital computer. This information exchange links the two computational domains and offers the combined advantages of the fast and flexible analog computer with the precise and logic-controllable digital computer. The extent of the information exchange between the two parts and the sophistication of the control structures and in

Analog Computer

  Analog Computer Analog computers work on continuous signals and consist of operational amplifiers, capacitors, resistors, potentiometers, diodes, switches, squarer cards, and patch cards. All the fundamental functions of computation, such as addition, subtraction, multiplication, integration, differentiation, and generation of different functions, can be carried out with an analog computer. The heart of an analog computer is the operational amplifier. The operational amplifier is a single-ended, high-gain DC coupled wide bandwidth unit, which has a very high open-loop gain, on the order of 105  to 108.  All the computer signals are referenced to a common ground. Offsets, drifts due to temperature variation, aging, and electronic noise are the main problems in the operational amplifier circuits. Hence special precautions are taken to reduce or eliminate them. Special care should be taken to minimize the electromagnetic and static coupling between different computing units and signal s

Supervisory Control Computer Functions and Tasks

  Supervisory Control Computer   Functions Supervisory control has three fundamental functions Calculation of the present state of the process in terms of key process parameters such as yield, severity, and efficiency. Calculation of critical process constraints, such as compressor capacity, column flooding limits, explosion limits, vacuum condenser capacity, and raw material. Calculation of new process conditions, in terms of set points, which will meet the requirements of the objective function. The objective function can be one of a number of goals such as maximizing throughput, yield, and profit or minimizing deviation. Tasks The supervisory control computer requires A process model Cost functions Optimization algorithms Constraints and limits The supervisory computer typically performs the following types of tasks Determines the process operating constraints, such as a column flooding condition in distillation or a surge condition of a compressor. Basic material balance, energy ba

Generic Features of DCS

  Generic Features of DCS Currently, most large-scale process plants such as oil refineries, petrochemical complexes, and various other processing plants are controlled by microcomputer-based DCS (distributed control systems). these systems generally include the following features Cathode ray tube (CRT)-based operator consoles and keyboards, which are used by plant operators or engineers to monitor and control the process Controllers, multifunction control modules, and programmable logic controllers (PLCs), which provide the basic control computation or operation  A communication network, which is used to transfer the information between control modules and operator consoles across the node on the network  I/O (Input/Output) modules, which are used to convert the field instrumentation signals from analog to digital and digital to analog form for controller modules and console displays Fieldbus communication links, which are used for communication between remote I/O devices and control

Core type and Shell type transformer

  Core type and   Shell type transformer Core type transformer In this transformer, the windings surround a considerable part of the core. Both the windings are bound on two opposite limbs of the core. This transformer is also called single window type transformer. Shell type transformer In this transformer, the core surrounds a major part of the windings. Both the windings are wound on the central limb of the core. This transformer is also called double window type transformer.