EE 27 Instrumentation and Controls Final Exam PDF

EE 27 – INSTRUMENTATION AND CONTROLS FIRST SEMESTER | A.Y. 2024 – 2025 | FINAL EXAM CAMANGON, J.H. Hydraulics and Pneumatics Hydraulics and Pneumatics component systems Hydraulics is a technology and applied scie...

EE 27 – INSTRUMENTATION AND CONTROLS FIRST SEMESTER | A.Y. 2024 – 2025 | FINAL EXAM CAMANGON, J.H. Hydraulics and Pneumatics Hydraulics and Pneumatics component systems Hydraulics is a technology and applied science using engineering, chemistry, and other sciences involving the mechanical properties and use of liquids. “hydraulics” refers to power produced by moving liquids. Modern hydraulics is defined as the use of confined liquid to transmit power, multiply force, or produce motion. Hydraulic refers to the science of using liquids to enable motion. Hydraulic are arrangements of pipes, hoses, pumps and other liquid - containing vessels that the contained liquid to perform work and move to another. 1. Fluid: oil for hydraulic systems, air for pneumatics. Pneumatic systems used in industry are commonly 2. Reservoir: storage tank. powered by compressed or compressed inert gases. A centrally located and electrically-powered compress 3. Hydraulic pump (compressor in pneumatics): powers cylinders, air motors, pneumatic actuators, and converts the mechanical energy into hydraulic energy by other pneumatic devices. forcing fluid from the reservoir into the system The liquid used is often a type of oil, but it can be 4. Fluid lines: transport the fluid to and from the pump another type of liquid as well. Hydraulic systems can be through the hydraulic system. used to perform work, but are susceptible to various type of corrosion. 5.Valves: control pressure, direction and flow rate of the hydraulic fluid. Pneumatics is the science and technology of pressurized air using piped, compressed air (or a similar gas, such as 6.Actuator: converts hydraulic energy into mechanical nitrogen) to transmit force and energy. energy to do work. “Pressure applied on a confined fluid is transmitted in The hydraulic systems are mainly used for precise all directions with equal force on equal areas” - Pascal control of larger forces. Liquids in motion or under pressure did useful work for Main Applications of the Hydraulic System man for many centuries before French scientist 1. Industrial: plastic processing machinery, steel philosopher Blaise Pascal and Swiss physicist Daniel making and primary metal extraction Bernoulli formulated the laws on which modern applications, automated production lines, hydraulic-power technology is based. machine tool industries, paper industries, Pascal's law, formulated in about 1650 loaders, crushes, textile machinery, R & D equipment and robotic systems etc. “pressure in a liquid is transmitted equally in all directions”; i.e, when water is made to fill a closed 2. Mobile hydraulics: tractors, irrigation system, container, the application of pressure at any point will be earthmoving equipment, material handling transmitted to all sides of the container. equipment, commercial vehicles, tunnel boring In the hydraulic press, Pascal's law is used to gain an equipment, rail equipment, building, and construction machinery and drilling rigs, etc. increase in force; a small force applied to a small piston in a small cylinder is transmitted through a tube to a large cylinder, where it presses equally against all sides 3. Automobiles: It is used in the systems like of the cylinder, including the large piston. breaks, shocks absorbers, steering system, wind shield, lift, and cleaning, etc Multiplication of Force 4. Marine applications: It mostly covers ocean- Since liquid transmit the same amount of pressure in all going vessels, fishing boats, and navel directions. The force transmitted to the output piston is equipment multiplied by a factor equal to the area ratio of the output piston to the input piston 5. Aerospace equipment: There are equipment and systems used for rudde control, landing gear, breaks, flight control and transmission etc. which are used in airplanes, rockets, and spaceships P EE 27 – INSTRUMENTATION AND CONTROLS FIRST SEMESTER | A.Y. 2024 – 2025 | FINAL EXAM CAMANGON, J.H. Control Valves Check Valves - are valves used to control conditions such as flow, pressure, and direction of flow. - Pressure control valves. - Flow control valves. - Directional control valves - Check Valves - Directional valves Pressure Control Valves - used to reduce the amount of pressure in a tank or system of pipes. Directional Valves CHECK VALVE Standard Calibrated Piloted Piloted with operated drainage Flow control valve Directional valve 2 ways – 2 3 way – 2 4 way – 2 4 ways –3 position position positions positions Used to control Fluid Flow Control for directional valves Mechanical Pushbutto Lever Pedal n Spring Cam Electric Electro- (solenoid) hydraulic Pneumatic Hydraulic Electric Electro- (prop) hydraulic (prop) EE 27 – INSTRUMENTATION AND CONTROLS FIRST SEMESTER | A.Y. 2024 – 2025 | FINAL EXAM CAMANGON, J.H. Symbols Pneumatic system In hydraulics: a) the pressure port is designated P b) return port R or T (for tank) c) two other ports are designated A and B. d) Boxes to identify normal and operating positions. e) Arrows to identify flow direction In Pneumatics: a) the pressure port is numbered (1) b) exhaust port (3). Air filters: these are used to filter out the contaminants c) other two are numbered (2) and (4). of the air Return stroke by Compressor: compressed air is generated by using air external force compressors Single acting cyl. Return stroke by Air cooler: during compression operation, air external spring temperature increases Single rod Dryer: the water vapor or moisture in the air is separated Double acting Control Valves: control valves are used to regulate, cylinder Double rod control and monitor for control of direction flow, pressure etc. Cushioning on Cyl with one side Air Actuator: air cylinders and motors are used to fixed stroke obtain the required movements of mechanical elements and cushioning Cushioning on of pneumatic systems both sides Electric motor: transforms electrical energy into Cushioning on mechanical energy. It is used to drive the compressor Cyl with one side adjustable Receiver tank: the compressed air coming from the stroke and cushioning Cushioning on compressor is stored in the air receiver both sides Shuttle valve Single-acting - has two air inlets ‘P1,’ and ‘P2’ and one air Telescopic cylinder outlet ‘A’. When compressed air enters through Double acting ‘P1 the sphere will seal and block the other inlet ‘P2’. Air can then flow from ‘P1’ to ‘A’. When the contrary happens, the sphere will block inlet ‘P1’, allowing air to flow from ‘P2’ to ‘A’ only Pneumatics - is an aspect of physics and engineering that is concerned with using energy in compressed gas to make something move or work. With pneumatics, valves control the flow of energy from pressurized gas, which is often simply compressed air. Pneumatic circuits Pneumatic actuator - device that converts energy from the pressurized gas into motion and often powered by - Pneumatic control systems can be designed in electric compressors the form of pneumatic circuits. A pneumatic circuit is formed by various pneumatic Pneumatics systems are similar to hydraulics in function, components, such as cylinders, directional but hydraulic systems use liquid to power movement and control valves, flow control valves, etc. work instead of gas. - Pneumatic circuits have the following functions: Pneumatic systems are simpler to design and simpler to manage than hydraulic systems, but hydraulic systems 1. To control the injection and release of are capable of greater pressures: up to 10,000 psi with compressed air in the cylinders. hydraulics, compared to about 100 psi with pneumatics 2. To use one valve to control another valve EE 27 – INSTRUMENTATION AND CONTROLS FIRST SEMESTER | A.Y. 2024 – 2025 | FINAL EXAM CAMANGON, J.H. Thermocouples exposed to the measurement temperature, the thermal resistance of the hot junction increases - is an electrical device consisting of two dissimilar electrical conductors forming an Grounded Junctions electrical junction. Construction is similar to that of insulated junction thermocouples, with the added feature that the junction - produces a temperature dependent voltage as a is electrically connected to a protected sheath. While result of Seebeck effect, and this voltage can be construction type is mechanically sturdy and protects interpreted to measure temperature. against corrosion, grounded junctions have faster response times than insulated junctions, due to a - widely used as temperature sensors. metallic connection to the protective sheath - widely used in science and industry. Applications include temperature measurement Series resistance along the lines of the thermocouple for kilns, gas turbine exhaust, diesel engines, and other industrial processes. Because thermocouples are conductors, the parasitic resistance in the conductors are attached circuitry may - ideally should be very simple measurement impact the signal. If the leads are too long or too thin, devices, with each type being characterized by a the total series resistance may cause signal degradation precise E(T) curve, independent of any other before the EMF reaches the cold junction details. Low grade materials used to construct the Thermocouples is composed of two dissimilar metal thermocouple and/or semiconductor wires joined together. To use a Some cheaper thermocouples are made of low thermocouple, we place junction in the test environment metallurgical graded materials. The used of such and keep two ends outside test environment at a materials could result in impurities in the construction reference temperature. that affect each batch of metal differently, producing Principle of thermocouples variable See beck coefficients Setup, as TH increases, electrons diffuse away from test Electrical isolation issues along the length of the lead environment along both chromel and alumel wires. This Several problems could emerge if the wrong type of creates a positive potential in the chromel-alumel insulation or poor-quality insulation is used to separate junction and negative potential at the two reference the two leads of the thermocouple. points Thermocouple type It is extremely important to keep the two ends of the thermocouple at the same known temperature. These can Each thermocouple type has a specified temperature be done by submerging the two reference points in a measurement range. A given thermocouple must be able mixture bath of ice and water (273K). to withstand the environmental conditions in which it will be applied. With a wide range of operation and Because thermocouples only give us the delta T value inexpensive construction, K-type thermocouples are between reference temperature and Th, if we do not some of the most common types in use. know the reference temperature we would be unable to determine TH The Thermocouple principle mainly depends on the three effects: Sometimes problem with the thermocouple itself lead to inaccurate readings. These problems my emerge from See beck effect damage that occurs as thermocouple ages. Peltier effect Poor hot junction thermal/electrical connection: the wrong thermoelectric voltage might be generated if the Thompson effect two conductors are not properly joined together at the hot junction See beck effect - occurs among two dissimilar metals. When the heat offers to anyone of the metal wire, then Bare wire thermocouple the flow of electrons supplies from hot metal wire to cold metal wire. Therefore, direct current stimulates in Two leads can be joined together in different ways. the circuit. Leads can be twisted together, soldered together, or welded together Peltier effect - opposite to the See beck effect. This effect states that the difference of the temperature can be Insulated Junction formed among any two dissimilar conductors by Based on the construction of the junction, insulated applying the potential variation among them junctions are more mechanically sturdy and corrosion- Thompson effect - states that as two disparate metals resistant compared to bare wire-type thermocouples. fix together and if they form two joints points then the However, because there is no metallic surface directly EE 27 – INSTRUMENTATION AND CONTROLS FIRST SEMESTER | A.Y. 2024 – 2025 | FINAL EXAM CAMANGON, J.H. voltage induces the total conductor’s length due to the ▪ Thermal reaction is fast gradient of temperature. This is a physical word which ▪ The operating range of temperature is wide demonstrates the change in rate and direction of temperature at an exact position ▪Cost is low and extremely consistent Main features of thermocouples The disadvantages include the following: ▪ extreme temperatures of range between −200℃ to over ▪ It has low accuracy + 2000℃ can be measured with thermocouples which is an advantage over both RTD and Thermistor ▪ The thermocouple recalibration is hard ▪They are the active transducers so they don’t require A thermocouple is a temperature sensor that is used to any external source for measuring of temperature as like gauge temperatures in manufacturing, machining, and RTD’s and Thermistors scientific applications, as well as everyday appliances. ▪ they are cheaper than both the RTD’s and Thermistors. A thermocouple can be useful to ensure surfaces, like steel or other metals or metal alloys, are appropriately ▪They have small accuracy as compared to RTD’s and heated for machining, or to gauge when a container or Thermistors so generally they are not used for high location is to warm and coolants need to introduced. precision work Types of thermocouple Factors that impact accuracy of Thermocouple readings Because different combinations of metals will produce different temperatures, and these different metals have The following factors may affect the temperature reading different durability and strength levels, researchers have at different stages of measurement and to varying produced standardized combinations to exploit degrees: maximum outcome potential in a standardized set of combinations ❖ thermocouple characteristics J Type Thermocouple ❖ cold junction measurement - most frequently used thermocouple, and it consist of a ❖ noisy environments positive (Iron) and a negative (Constantan) legs. Application: reducing vacuum, oxidizing and inert ❖ linearization environments. Construction of Thermocouple temperature range: is low and lifespan is lesser of high comprises of two different metal wires and that are temperature compare with the K-type. It is equal to the connected together at the junction end. The junction K-type in conditions of reliability and expense thinks as the measuring end. The end of the junction is K Type Thermocouple classified into three type’s namely ungrounded, grounded and exposed junction - most common type of thermometer, and it consists of a positive (Chromel) and a negative (Alumel) legs. Ungrounded junction - the conductors are totally separated from the protecting cover. This application of - suggested for inert or oxidizing atmosphere up to this junction mainly include high-pressure application 2300℉ cycling and not suggested for 1800℉ due to works. The main benefit of using this junction is to EMF variation from hysteresis decrease the stray magnetic field effect - quite stable as well as accurate at high-temperatures Grounded junction - the metal wires as well as N Type Thermocouple protecting cover are connected together. This function is used to measure the temperature in the acidic - consist of positive (Nicrosil) and a negative (Nisil) atmosphere legs. It has superior resistance for degradation due to the cycling of temperature, hysteresis and green rot than the Exposed junction - applicable in the areas where quick K-type. It is normally very expensive response is required. This type of junction is used to measure the gas temperature. The metal used to make T Type Thermocouple the thermocouple basically depends on the calculating range of temperature - consist of a positive (copper) and a negative (Constantan)legs. The advantages include the following: - application: oxidizing, reducing, in the vacuum, and ▪ Accuracy is high inert environments, maintains stable resistance to decomposition in most environments as well as high ▪ It is Robust and can be used in environments like harsh stability on sub-zero temperatures as well as high vibration. EE 27 – INSTRUMENTATION AND CONTROLS FIRST SEMESTER | A.Y. 2024 – 2025 | FINAL EXAM CAMANGON, J.H. E Type Thermocouple - consist of a positive (chromel) and a negative Sensors and Actuators (Constantan)legs, and it is not focus on oxidization in There are many different types of transducers, but at atmosphere. this type also has a maximum EMF per their most basic, they can be divided into two groups: degree like any typical type of thermocouple. But, this Input (sensor) and output (actuator). type must be defended from sulfurous environments Input transducers take some sort of physical energy – S Type Thermocouple such as sound waves, temperature, or pressure – and - used in extremely high temperature applications. converts into a signal that can be read Application: Pharmaceutical as well as Biotech Actuators take an electronic signal and convert it into a industries, used in low-temperature applications due to physical energy. A stereo speaker works by transforming stability and high accuracy the electronic signal of a recording into physical sound waves B Type Thermocouple, Electric motors are another common form of - is extremely used in high temperature applications, and electromechanically transducer, converting electrical the temperature limit of this is highest than other types energy into mechanical energy to perform task. of thermocouples discussed. It maintain a high level of precision and constancy at very high temperatures. Combining transducers R Type Thermocouple Many devices work by combining sensors and actuators to convert energy from one form to another and then - is applicable for high-temperature. It consists of the back again high percentage of (Rhodium) chemical elements than the S-type which will make it more costly. This type is Ultra sound imaging also works by converting energy very comparable to the S-type in terms of the act. multiple times. A piezoelectric transducer is used to Sometimes, it is used in low-temperature applications convert electricity into high frequency sound waves due to its stability and high accuracy (ultrasound), which are focused by the machine and aimed at body tissues. These waves bounce back to the machine, where a transducer converts them into electrical signal again. The signal are processed and sent to a monitor to produce an image of the body tissues. Efficiency As in all energy conversions, some energy is lost when transducers operate, but some are more efficient than others A radio antenna, which turns radio frequency power into an electromagnetic field, is one example of an efficient transducer. When the antenna is operating well, this process can be more than 80% efficient. Most electrical motors, by contrast are less than 50% efficient, while Transducers regular incandescent light bulbs, because of the amount of energy that is lost as heat, are less than 10% efficient. - electric or electronic devices that transform energy from one form of another. For example, a stereo speaker Obligation of transducers converts the electrical signals of recorded music into Transducers device that converts input energy into sound. Many people think of a transducer are being a output energy, the latter usually differing in kind but complicated, technical device designed to gather or bearing a known relation to input. transfer information. In reality, however, anything that converts energy can be considered a transducer Originally, the term referred to a device that converted mechanical stimuli into electrical output, but it has been broadened to include devices that sense all form of stimuli – such as heat, radiation, sound, strain, vibration, pressure, acceleration and so on – and that can produce output signals other than electrical – such as pneumatic or hydraulic. Many measuring and sensing devices, as well as loudspeakers, thermocouples, microphones, and phonograph pickups, may be termed transducers. EE 27 – INSTRUMENTATION AND CONTROLS FIRST SEMESTER | A.Y. 2024 – 2025 | FINAL EXAM CAMANGON, J.H. ▪ Silicon is the piezo resistive material most used for its high elasticity and piezoresistive coefficient Classification of transducers ▪ Need for correction of the measurement by temperature Electrical transducers may be classified as active or ▪ Wide measuring range: 103 – 108 Pa ▪ High precision passive. 0.1% (0.5% real) Active transducers generate electric current or voltage ▪ Reduce price. directly in response to stimulation. Active transducers doesn’t require any power source for their operation. Types of temperature transducers Example: Thermocouple ▪ Resistance thermometers Passive transducer produces a change in some passive ▪Resistance Temperature detectors electrical quantity, such as capacitance, resistance or inductance, as a result of stimulation. Passive ▪ Thermistors transducers usually require additional electric energy. ▪ IC Sensors A simple example of a passive transducers is a device containing a length of wire and a moving contact ▪ Thermocouples touching the wire. The position of the contact determines ▪ Humidity Transducers the effective length of the wire and, thus, the resistance offered to electric current flowing through it. This is - Resistance thermometers the measurement of called a linear-displacement transducer, or linear temperatures using resistance probes depends on potentiometer the characteristics of resistance as a function of temperature that are characteristic of the Types of transducers detection element. There are variety of transducer types - Resistance temperature detector (RTD) is a. pressure transducer based on the principle that the resistance of all b. piezoelectric transducer metals depends on the temperature. c. ultrasonic transducer - Thermistor are electronic semiconductors with a negative resistance temperature coefficient of d. temperature transducer high value and which present a linear voltage- Pressure transducer are sensors that transform the current characteristic curve as long as the pressure of a medium into an electrical signal for further temperature remains constant. analysis. The measurement of pressure can be done using various physical principles - IC sensors Integrated circuit sensors solve the problem of linearity and offer high levels of ▪ Molecular bombardment on very thin sheet. performance. ▪ Pressure sensor chips - thermocouple are widely use, since they offer a ▪ Accelerometers with integrated technology much wider temperature range and a more robust construction than other types. ▪ Integrated piezoresistive technology Piezoelectric transducers Types of pressure transducers A piezo electric crystal transducer/sensor is an active A. Capacitive transducers sensor and it does not need the help of an external power ▪ Wide measuring range: 103 - 108 Pa as it is self-generating. ▪ High precision 0.1% ▪ Piezoelectric Quartz Crystal - A quartz crystal is a piezoelectric material that can generate a voltage ▪ High resistance (temperature, vibrations, etc.) proportional to the stress applied upon it. ▪ High price ▪ The main principle of a piezoelectric transducer is that B. Piezoresistive transducers a force, when applied on the quartz crystal, produces electric charges on the crystal surface. ▪ They use piezoresistive materials (their electrical resistance varies with pressure) Applications The most used material is silicon (transducer integrated ▪ Due to excellent frequency response, it is normally in a chip) used as an accelerometer, where the output, is in the order of (1-30)mV per gravity of acceleration. ▪ They are the most used (80% of the market) EE 27 – INSTRUMENTATION AND CONTROLS FIRST SEMESTER | A.Y. 2024 – 2025 | FINAL EXAM CAMANGON, J.H. ▪ The device is usually designed for use as a pre- These handheld devices consist of a small display to tensional bolt so that both tensional and compression make the instruction that has been programmed visible. force measurements can be made. These are compact and easy to used devices, but these handheld devices have limited capabilities ▪ Can be used for measuring force, pressure and displacement in terms of voltage. Most popularly a Personal Computer (PC) is used for Advantages programming the PLC in conjunction with the software ▪ Very high frequency response. given by the manufacturer ▪ Self-generating, so no need of external source. By using this PC we can run the program in either online or offline mode, and can also edit, monitor, diagnose and ▪ Simple to use as they have small dimensions and large troubleshoot the program of the PLC measuring range. The way of transferring the program to the PLC wherein ▪ Barium titanate and quartz can be made in any desired the PC consist of program code corresponding to control shape and form. It also has a large dielectric constant. application which is transferred to the PLC CPU via The crystal axis is selectable by orienting the direction programming cable of orientation. Ladder Logic PLC Programming Disadvantage Among several programming languages ladder logic ▪ It is not suitable for measurement in static condition. ▪ diagram is the most basic and simplest form of Since the device operates with the small electric charge, programming the PLC. they need high impedance cable for electrical interface. Here two horizontal lines are called rung which ▪ The output may vary according to the temperature connected between two vertical lines called rails. variation of the crystal. Each rung establishes the electrical continuity between ▪ The relative humidity rises 85% or falls 35%, its output positive (L) and negative rails (N) so that the current will be affected. If so, it has to be coated with wax or flows from the input to the output devices polymer material PLC - PROGRAMMABLE LOGIC CONTROLLER - is a specialized computer used to control machines and process. - Eliminates much of the hard wiring that was associated with conventional relay control circuits. - The program takes place of much of the external wiring that would be required to control of a process Some of the symbols used in ladder logic programming. PLC – is an industrial-grade digital computer designed Input switches, are types include normally closed and to perform control functions – especially for industrial normally opened. applications In addition to given functional symbols, there are several functions like timer, counter, PID, etc. which are stored The majority of PLC today are modular, allowing the in the standard library to program complex task user to add an assortment of functionality including discrete control, analog control, serial communication, and high speed networking Various types of programming devices are used to enter, modify and troubleshoot a PLC program. These programming terminal devices include handheld and PC base devices. In a handheld programming device method, a proprietary device is connected to PLC through a connecting cable These device consist of a set of keys that allows to enter, edit and dump the code into the PLC. EE 27 – INSTRUMENTATION AND CONTROLS FIRST SEMESTER | A.Y. 2024 – 2025 | FINAL EXAM CAMANGON, J.H. group of people is involved. In addition to organization, a successful control solution also depends on the ability to implement it. The programmer must understand the Step by step procedure for programming PLC control task and controlled devices, choose the correct equipment for the job (hardware and software), PLC using ladder logic and understand the PLC system. Step 1: Analyze and get the idea of control application Principles of Operation The primary step to program the PLC is to get the idea for which you are going to develop an application-based program. Step 2: List all the conditions and get the design using flowchart The variables of the project are M: motor, A: input switch 1, B: input switch 2, L: LED and Bu: buzzer, and the designing of the logic is easy with the implementation of flow chart, which is given for the application Step 3: Open and configure the PLC Programming Software Open the programming software installed in the PC that comes with PLC hardware. Select the hardware model of the PLC in the software and configure it with appropriate input and output modules. Select the ladder language (LD) form the list of the programming languages, and choose the hardware processor and give a name for the program Step 4: Add the required Rungs and Address them Add the required rungs based on the control application logic and give the address to each and every input and outputs Step 5: check the errors and stimulate it Locate the online section in the menu bar and select online. Check for the errors and make necessary changes after selecting offline. Again, go online and select Run option for simulate it Step 6: download the program to PLC CPU Memory After the successful stimulation of the program, download the program to CPU by selecting the Download option through a network or communication cable PLC Components. input module: function - convert incoming signals into signals that can be processed by the PLC, and to pass those signals to the central control unit. The reverse task is performed by an output module. This converts the PLC signal into signals suitable to operate and invoke the plant actuators. The actual processing of the signals is undertaken in the central control unit and with respect to the program stored in the memory Organization is a key word when programming and implementing a control solution. The larger the project, the more organization is needed, especially when a EE 27 – INSTRUMENTATION AND CONTROLS FIRST SEMESTER | A.Y. 2024 – 2025 | FINAL EXAM CAMANGON, J.H. The RUN operation for the process control scheme can be describe by the following sequence of events: - First the pressure switch, temperature switch, and pushbutton inputs are examined and their status is recorded in the controller’s memory. - A closed contact is recorded in memory as logic 1 and an open contact as logic 0 - Next the ladder diagram is evaluated, with each internal contact given an OPEN or CLOSED status according to its recorded 1 or 0 state. - When the states of the input contacts provide logic continuity from left to right across the rung, the output coil memory location is given a logic 1 value and the output module interface contacts will close. - When there is no logic continuity of the program rung, the output coil memory location is set to logic 0 and the output module interface contacts will be open