Basic Electrical Engineering BTEE16F1500 UNIT- 4 Tariff, Protective Devices and Sensors Hand Notes By
Mr. Mahesh Kumar Assistant Professor School of Electrical &Electronics Engg. Rukmini Knowledge Park, Kattigenahalli Yelahanka, Bangalore, INDIA
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Unit IV
Tariff, Protective Devices and Sensors Tariff schemes, basic concepts of domestic wiring and types, earthing, protective fuses, MCB. Sensors: pressure sensor, strain gage, proximity sensor, displacement sensor, rotary encoder and ultrasonic sensors (applications in relevant disciplines- ref to 8 and 9) Tariff – Introduction: Electrical energy produced by the power system is delivered to a large no customers. The tariff becomes the attention for the electric supply company. The company has to ensured that the tariff such that it not only recovers total cost of producing electrical energy but also earns profit on the capital investment. Tariff types: 1 Simple tariff 2.Flat rate tariff 3.Block rate tariff 4.Two part tariff 5.Maximum demand tariff 6. Power factor tariff 7.Three part tariff Simple Tariff: Definition: When there is a fixed rate per unit of energy consumed, it is known as simple tariff (Uniform Rate Tariff). This is the most simplest of all tariff. In this type, the price charged per unit is constant. It means, the price will not vary with increase or decrease in number of units used. Disadvantages: The cost per unit delivered is high. There is no discrimination among various types of consumers. Flat Rate Tariff: Definition: When different types of consumers are charged at different uniform per unit rates, it is said to be Flat rate Tariff. In this type, the consumers are grouped into different classes. Each class is charged at different uniform rate. the different classes of consumers may be taken into account of their diversity and load factors. Since this type of tariff varies according to the way of supply used, separate meters are required for lighting load, power load etc. Block rate tariff: When a given block of energy is charged at a specified rate and the succeeding blocks of energy are charged at progressively reduced rates is called as block rate tariff. In this type, the energy consumption is divided into many blocks and price per unit is fixed in each block.
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Two Part tariff: When the rate of electrical energy is charged on the basis of maximum demand of the consumer and the units consumed it is called two-part tariff. In this type, the total charge to be made from the consumer is split into two components. ie, fixed charges and running charges. The fixed charges depend upon the number of units consumed by the customer. Thus the consumer is charged at a certain amount per kW of maximum demand + a certain amount per kWh of energy consumed. Total charges = Rs (X x kW + Y x kWh) It is easily understood by the consumer. It recovers fixed charges which depend upon the maximum demand of the consumer independent of the units consumed. This form of tariff is generally used for industrial customers. Disadvantages Consumer has to pay the fixed charges irrespective of the fact whether he has consumed or not the electrical energy. There is always error in assessing the maximum demand of the consumer. Maximum demand tariff: It is similar to two-part tariff. The only difference is the maximum demand of the consumer is calculated by installing a maximum demand meter at his premises. This type of tariff is mostly applied to the bulk consumers. Time-of-day tariffs (TOD, peak-load): Rates vary depending on when the service is being used. For example, the operator would charge higher prices during peak use hours and lower prices during off-peak hours to reflect the cost of generation. This structure requires sophisticated measurement of customer usage, such as metering technologies. It encourages consumers to use less power during peak hours. With decreasing costs of TOD meters, use of the TOD tariff structure is becoming more common. Seasonal tariffs: These rates allow higher charges for electricity in summer and winter when demand for cooling or heating is higher. Typically they are used in climates where utilities experience significant seasonal cost differences. With traditional regulation, seasonal rates reduce net revenue stability for utilities by concentrating revenue into the weather-sensitive seasons. 1. Define Tariff and explain its main objectives? The cost of electrical generation of electrical energy consists of fixed cost and running cost. Since the electricity generated is to be supplied to the consumers, the total cost of generation has to be recovered from the consumers. Tariffs or energy rates are the different methods of charging the consumers for the consumption of energy. It is desirable to charge according to the maximum demand (KW) and the energy consumed (KWh). Objectives: a. Recovery of cost of capital investment in generating equipment, transmission and distribution system. b. Recovery of the cost of operation, supplies and maintenance. c. Recovery of the cost material, equipment, billing and collection, cost as well as for miscellaneous services. d. A net return on the total capital investment must be ensured. 2. What are requirements of Tariff? a. It should be easier to understand b. It should provide low rates for high consumption. c. It should be uniform over large population d. It should encourage the consumers having high load factors.
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3. 4. 5. 6. 7. 8.
e. It should provide incentives for using power during off peak hours f. It should have a provision of penalty for low PF What are the different types of tariffs? Explain simple tariff and its disadvantages? Difference between simple tariff and flat rate tariff? Write down the advantages and disadvantages of Two part tariff? Define power factor tariff? Explain Three part tariff?
DOMESTIC WIRING Introduction A network of wires drawn connecting the meter board to the various energy consuming loads (lamps, fans, motors etc) through control and protective devices for efficient distribution of power is known as electrical wiring. Electrical wiring done in residential and commercial buildings to provide power for lights, fans, pumps and other domestic appliances is known as domestic wiring. There are several wiring systems in practice. They can be classified into: Tree system - In this system branches are tapped from the main circuit at required points. This involves many joints making the location of the fault point difficult. Though the method is economical it is visually unappealing with scattered fuses and is affected by large voltage drops. Distribution system - This system is more organized in the sense that the main circuit is drawn to several distribution centers and connected to the distribution boards. Branches are tapped from these distribution boards. This system of wiring has an aesthetic appeal, as they are without joints and also makes the location of the fault point easier. All the points are maintained almost at the same potential. Each circuit is provided with an independent fuse. Provides flexibility for repair and maintenance. This system is widely preferred for indoor wiring though expensive. Typs of Wiring: Cleat wiring CTS wiring or TRS wiring or batten wiring Metal sheathed wiring or lead sheathed wiring Casing and capping Conduit wiring.
1. Cleat wiring:
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In this type of wiring, insulated conductors (usually VIR, Vulcanized Indian Rubber) are supported on porcelain or wooden cleats. The cleats have two halves one base and the other cap. The cables are placed in the grooves provided in the base and then the cap is placed. Both are fixed securely on the walls by 40mm long screws. The cleats are easy to erect and are fixed 4.5 – 15 cms apart. This wiring is suitable for temporary installations where cost is the main criteria but not the appearance.
Advantages 1. 2. 3. 4. 5.
Easy installation Materials can be retrieved for reuse Flexibility provided for inspection, modifications and expansion. Relatively economical Skilled manpower not required.
Disadvantages: 1. Appearance is not good 2. Open system of wiring requiring regular cleaning. 3. Higher risk of mechanical injury. Casing and Capping: It consists of insulated conductors laid inside rectangular, teakwood or PVC boxes having grooves inside it. A rectangular strip of wood called capping having same width as that of casing is fixed over it. Both the casing and the capping are screwed together at every 15 cms. Casing is attached to the wall. Two or more wires of same polarity are drawn through different grooves. The system is suitable for indoor and domestic installations. Advantages: 1. Cheaper than lead sheathed and conduit wiring. 2. Provides good isolation as the conductors are placed apart reducing the risk of short circuit. 3. Easily accessible for inspection and repairs. 4. Since the wires are not exposed to atmosphere, insulation is less affected by dust, dirt and climatic variations. Disadvantages: 1. Highly inflammable. 2. Usage of unseasoned wood gets damaged by termites. 3. Skilled workmanship required.
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Conduit wiring: In this system PVC (polyvinyl chloride) or VIR cables are run through metallic or PVC pipes providing good protection against mechanical injury and fire due to short circuit. They are either embedded inside the walls or supported over the walls, and are known as concealed wiring or surface conduit wiring (open conduit) respectively. The conduits are buried inside the walls on wooden gutties and the wires are drawn through them with fish (steel) wires. The system is best suited for public buildings, industries and workshops.
Advantages. 1. No risk of fire and good protection against mechanical injury. 2. The lead and return wires can be carried in the same tube. 3. Earthing and continuity is assured. 4. Waterproof and trouble shooting is easy. 5. Shock- proof with proper earthing and bonding 6. Durable and maintenance free 7. Aesthetic in appearance Disadvantages: 1. Very expensive system of wiring. 2. Requires good skilled workmanship. 3. Erection is quiet complicated and is time consuming. 4. Risk of short circuit under wet conditions (due to condensation of water in tubes). FACTORS AFFECTING THE CHOICE OF WIRING SYSTEM: The choice of wiring system for a particular installation depends on technical factors and economic viability. 1. Durability: Type of wiring selected should conform to standard specifications, so that it is durable i.e. without being affected by the weather conditions, fumes etc. 2. Safety: The wiring must provide safety against leakage, shock and fire hazards for the operating personnel. 3. Appearance: Electrical wiring should give an aesthetic appeal to the interiors 4. Cost: It should not be prohibitively expensive. 5. Accessibility: The switches and plug points provided should be easily accessible. There must be provision for further extension of the wiring system, if necessary. 6. Maintenance Cost: The maintenance cost should be a minimum 7. Mechanical safety: The wiring must be protected against any mechanical damage
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EARTHING: The potential of the earth is considered to be at zero for all practical purposes as the generator (supply) neutral is always earthed. The body of any electrical equipment is connected to the earth by means of a wire of negligible resistance to safely discharge electric energy, which may be due to failure of the insulation, line coming in contact with the casing etc. Earthing brings the potential of the body of the equipment to ZERO i.e. to the earth’s potential, thus protecting the operating personnel against electrical shock. The body of the electrical equipment is not connected to the supply neutral because due to long transmission lines and intermediate substations, the same neutral wire of the generator will not be available at the load end. Even if the same neutral wire is running it will have a self-resistance, which is higher than the human body resistance. Hence, the body of the electrical equipment is connected to earth only. Thus earthing is to connect any electrical equipment to earth with a very low resistance wire, making it to attain earth’s potential. The wire is usually connected to a copper plate placed at a depth of 2.5 to 3meters from the ground level. The earth resistance is affected by the following factors: 1. Material properties of the earth wire and the electrode 2. Temperature and moisture content of the soil 3. Depth of the pit 4. Quantity of the charcoal used Necessity of Earthing: 1. To protect the operating personnel from danger of shock in case they come in contact with the charged frame due to defective insulation. 2. To maintain the line voltage constant under unbalanced load condition. 3. Protection of the equipments 4. Protection of large buildings and all machines fed from overhead lines against lightning. Methods of Earthing: The important methods of earthing are the plate earthing and the pipe earthing. The earth resistance for copper wire is 1 ohm and that of G I wire less than 3 ohms. The earth resistance should be kept as low as possible so that the neutral of any electrical system, which is earthed, is maintained almost at the earth potential. The typical value of the earth resistance at powerhouse is 0. 5 ohm and that at substation is 1 ohm. 1. Plate earthing 2. Pipe earthing
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Plate Earthing In this method a copper plate of 60cm x 60cm x 3.18cm or a GI plate of the size 60cm x 60cm x 6.35cm is used for earthing. The plate is placed vertically down inside the ground at a depth of 3m and is embedded in alternate layers of coal and salt for a thickness of 15 cm. In addition, water is poured for keeping the earth electrode resistance value well below a maximum of 5 ohms. The earth wire is securely bolted to the earth plate. A cement masonry chamber is built with a cast iron cover for easy regular maintenance. Excavation on earth for a normal earth Pit size is 1.5M X 1.5M X 3.0 M. Use 500 mm X 500 mm X 10 mm GI Plate or Bigger Size for more Contact of Earth and reduce Earth Resistance. Make a mixture of Wood Coal Powder Salt & Sand all in equal part Wood Coal Powder use as good conductor of electricity, anti corrosive, rust proves for GI Plate for long life. The purpose of coal and salt is to keep wet the soil permanently. The salt percolates and coal absorbs water keeping the soil wet. Care should always be taken by watering the earth pits in summer so that the pit soil will be wet. Coal is made of carbon which is good conductor minimizing the earth resistant. Salt use as electrolyte to form conductivity between GI Plate Coal and Earth with humidity. Sand has used to form porosity to cycle water & humidity around the mixture. Put GI Plate (EARTH PLATE) of size 500 mm X 500 mm X 10 mm in the mid of mixture.
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Pipe Earthing Earth electrode made of a GI (galvanized) iron pipe of 38mm in diameter and length of 2m (depending on the current) with 12mm holes on the surface is placed upright at a depth of 4.75m in a permanently wet ground. To keep the value of the earth resistance at the desired level, the area (15 cm) surrounding the GI pipe is filled with a mixture of salt and coal. The efficiency of the ear thing system is improved by pouring water through the funnel periodically. The GI earth wires of sufficient cross- sectional area are run through a 12.7mm diameter pipe (at 60cms below) from the 19mm diameter pipe and secured tightly at the top as shown in the following figure. When compared to the plate earth system the pipe earth system can carry larger leakage currents as a much larger surface area is in contact with the soil for a given electrode size. The system also enables easy maintenance as the earth wire connection is housed at the ground level.
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PROTECTIVE DEVICES Protection for electrical installation must be provided in the event of faults such as short circuit, overload and earth faults. The protective circuit or device must be fast acting and isolate the faulty part of the circuit immediately. It also helps in isolating only required part of the circuit without affecting the remaining circuit during maintenance. The following devices are usually used to provide the necessary protection: Fuses Relays Miniature circuit breakers (MCB) Earth leakage circuit breakers (ELCB) FUSE The electrical equipments are designed to carry a particular rated value of current under normal circumstances. Under abnormal conditions such as short circuit, overload or any fault the current raises above this value, damaging the equipment and sometimes resulting in fire hazard. Fuses are pressed into operation under such situations. Fuse is a safety device used in any electrical installation, which forms the weakest link between the supply and the load. It is a short length of wire made of lead / tin /alloy of lead and tin/ zinc having a low melting point and low ohmic losses. Under normal operating conditions it is designed to carry the full load current. If the current increases beyond this designed value due any of the reasons mentioned above, the fuse melts (said to be blown) isolating the power supply from the load as shown in the following figures. CHARACTERISTICS OF FUSE MATERIAL The material used for fuse wires must have the following characteristics 1. 2. 3. 4.
Low melting point Low ohmic losses High conductivity Lower rate of deterioration
Different types of fuses: Re-wirable or Kit -Kat fuses: These fuses are simple in construction, cheap and available up-to a current rating of 200A. They are erratic in operation and their performance deteriorates with time. Plug fuse: The fuse carrier is provided with a glass window for visual inspection of the fuse wire. Cartridge fuse: Fuse wire usually an alloy of lead is enclosed in a strong fiber casing. The fuse element is fastened to copper caps at the ends of the casing. They are available up-to a voltage rating of 25kV. They are
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used for protection in lighting installations and power lines. Miniature Cartridge fuses: These are the miniature version of the higher rating cartridge fuses, which are extensively used in automobiles, TV sets, and other electronic equipments. Transformer fuse blocks: These porcelain housed fuses are placed on secondary of the distribution transformers for protection against short circuits and overloads. Expulsion fuses: These consist of fuse wire placed in hollow tube of fiber lined with asbestos. These are suited only for outdoor use for example, protection of high voltage circuits. Semi-enclosed re-wirable fuses: These have limited use because of low breaking capacity. Time-delay fuse: These are specially designed to withstand a current overload for a limited time and find application in motor circuits. MCBs or Miniature Circuit Breakers MCB’s are electromechanical devices which protect an electrical circuit from an overcurrent. The overcurrent, in an electrical circuit, may result from short circuit, overload or faulty design. An MCB is a better alternative to a Fuse since it does not require replacement once an overload is detected. Unlike fuse, an MCB can be easily reset and thus offers improved operational safety and greater convenience without incurring large operating cost.The principal of operation is simple. An MCB functions by interrupting the continuity of electrical flow through the circuit once a fault is detected. In simple terms MCB is a switch which automatically turns off when the current flowing through it passes the maximum allowable limit. Generally MCB are designed to protect against over current and over temperature faults (over heating). There are two contacts one is fixed and the other moveable. When the current exceeds the predefined limit a solenoid forces the moveable contact to open (i.e., disconnect from the fixed contact) and the MCB turns off thereby stopping the current to flow in the circuit. In order to restart the flow of current the MCB is manually turned on. This mechanism is used to protect from the faults arising due to over current or over load. To protect against fault arising due to over heating or increase in temperature a bi-metallic strip is used. MCBs are generally designed to trip within 2.5 millisecond when an over current fault arises. In case of temperature rise or over heating it may take 2 seconds to 2 minutes for the MCB to trip. This article covers the insight of a single pole MCB commonly used in the house hold. The following image shows the different internal parts of an MCB with top casing removed. The subsequent sections will examine each part and its function. Questions On Wiring, Earthing 1. Mention the different types of wiring. With relevant circuit diagrams and switching tables, explain the two – way and the three way control of lamps. 2. Explain the different types of wiring used in practice 3. Explain in brief the following: i. Fuses ii. Specification of wires iii. Earthing and its necessity 4. Sketch any one type of Earthing and indicate why such Earthing of electrical equipments is necessary
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5. With a neat sketch explain any one method of Earthing electrical appliance. 6. Define domestic wiring. What important factors are to be considered in domestic wiring? Mention the difference types of wiring in practice. 7. What do you understand by “Earthing”? With a neat diagram explain Plate Earthing. 8. With a neat sketch explain the Pipe Earthing method.
Sensors Def: A device which detects or measures a physical property and records, indicates, or otherwise responds to it. Types of Sensors 1. Acoustic & sound sensors e.g.: Microphone, Hydrophone. 2. Automotive sensors e.g.: Speedometer, Radar gun, Speedometer, fuel ratio meter. 3. Chemical Sensors e.g.: Ph sensor, Sensors to detect presences of different gases or liquids. 4. Electric & Magnetic Sensors e.g.: Galvanometer, Hall sensor (measures flux density), Metal detector. 5. Environmental Sensors e.g.: Rain gauge, snow gauge, moisture sensor. 6. Optical Sensors e.g.: Photodiode, Phototransistor, Wave front sensor. 7. Mechanical Sensors e.g.: Strain Gauge, Potentiometer (measures displacement). 8. Thermal & Temperature sensors. e.g.: Calorimeter, Thermocouple, Thermistor, Gardon gauge. 9. Proximity & Presences sensors: A proximity or presences sensor is the one which is able to detect the presences of nearby objects without any physical contact. They usually emit electromagnetic radiations and detect the changes in reflected signal if any. e.g.: Doppler radar, Motion detector. Pressure Sensors Since a long time, pressure sensors have been widely used in fields like automobile, manufacturing, aviation, bio medical measurements, air conditioning, hydraulic measurements etc. A few prominent areas where the use of pressure sensors is inevitable are: 1. Touch Screen Devices: The computer devices and smart phones that have touch screen displays come with pressure sensors. Whenever slight pressure is applied on the touch screen through a finger or the stylus, the sensor determines where it has been applied and accordingly generates an electric signal that informs the processor. Usually, these sensors are located at the corners of the screen. So when the pressure is applied, usually two or more such sensors act to give precise location information of the location. 2. Automotive Industry: In automotive industry, pressure sensors form an integral part of the engine and its safety. In the engine, these sensors monitor the oil and coolant pressure and regulate the power that the engine should deliver to achieve suitable speeds whenever accelerator is pressed or the brakes are applied to the car. For the purpose of safety, pressure sensors constitute an important part of anti-lock braking system (ABS). This system adapts to the road terrain and makes sure that in case of braking at high speeds, the tires don’t lock and the vehicle doesn’t skid. Pressure sensors in the ABS detail the processor with the conditions of the road as well as the speed with which the vehicle is moving. Air bag systems also use pressure sensors so that the bags get activated to ensure the safety of the passengers whenever high amount of pressure is experienced by the vehicle. 3. Bio Medical Instrumentation: In instruments like digital blood pressure monitors and ventilators, pressure sensors are needed to optimize them according to patient’s health and his requirements. 4. Industrial Uses: Pressure sensors are used to monitor gases and their partial pressures in industrial units so that the large chemical reactions take place in precisely controlled environmental conditions. In oil industry, sensors detail with the depth that the oil rig has reached while exploring. 5. Aviation: In the airplanes, these sensors are needed to maintain a balance between the atmospheric pressure and the control systems of the airplanes. This not only protects the circuitry and various internal components of the airplane but also gives exact data to the system about the external environment. Also, particular levels of air pressure need to be maintained in the cockpit and the passengers lobby to provide nominal ground like breathing conditions.
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6. Marine Industry: For ships and submarines, pressure sensors are needed to estimate the depth at which they are operating and for detailing the marine conditions so that the electronic systems can remain safe. Oxygen requirements of under water projects are also regulated by the pressure sensors. Proximity Sensors Type
Use
Inductive
Detection of metallic objects
Capacitive
Detection of metallic and non-metallic objects
Photoelectric
Use light sensitive elements to detect objects
Magnetic
Detects the presence of permanent magnets
Photoelectric sensors Direct Reflection (Diffused) - emitter and receiver are housed together and use the light reflected directly off the object for detection. In the use of these photocells, it is important to bear in mind the color and the type of surface of the object. With opaque surfaces, the sensing distance is affected by the color of the object. Light colors correspond to the maximum distances and vice versa. In the case of shiny objects, the effect of the surface is more important than the color. The sensing distance in the technical data is related to matte white paper. Reflection with Reflector (Retro reflective) - emitter and receiver are housed together and requires a reflector. An object is detected when it interrupts the light beam between the sensor and reflector. These photocells allow longer sensing distances, as the rays emitted are almost totally reflected towards the receiver. Polarized Reflection with Reflector - similar to Reflection with Reflector, these photocells use an anti-reflex device. The use of such a device, which bases its functioning on a polarized band of light, offers considerable advantages and secure readings even when the object to be sensed has a very shiny surface. They are not in the technical data affected by random reflections. Thru Beam - emitter and receiver are housed separately and detect an object when it interrupts the light beam between the emitter and receiver. These photocells allow for the longest distances. Strain gauge Sensor The strain gauge has been in use for many years and is the fundamental sensing element for many types of sensors, including pressure sensors, load cells, torque sensors, position sensors, etc. The majority of strain gauges are foil types, available in a wide choice of shapes and sizes to suit a variety of applications. They consist of a pattern of resistive foil which is mounted on a backing material. They operate on the principle that as the foil is subjected to stress, the resistance of the foil changes in a defined way.
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The strain gauge is connected into a Wheatstone Bridge circuit with a combination of four active gauges (full bridge), two gauges (half bridge), or, less commonly, a single gauge (quarter bridge). In the half and quarter circuits, the bridge is completed with precision resistors.
The complete Wheatstone Bridge is excited with a stabilised DC supply and with additional conditioning electronics, can be zeroed at the null point of measurement. As stress is applied to the bonded strain gauge, a resistive changes takes place and unbalances the Wheatstone Bridge.
Ref: http://web.deu.edu.tr/mechatronics/TUR/strain_gauge.htm Displacement Sensors Measurements of size, shape and position utilize displacement sensors. Ex: diameter of part under stress (direct), Movement of microphone diaphragm to quantify liquid movement through heart (Indirect). Displacement Sensors for Differentiation: Smart Sensors designed to allow anyone to easily use advanced sensing performance. Even with laser, proximity, contact, and other sensing methods, operations are essentially the same. Rotary Encoder Rotary encoders are electromechanical devices used for sensing in myriad applications — on motors paired with drives and automated machinery for everything from consumer electronics, elevators, and conveyor speed monitoring to position control on automated industrial machines and robotics. They track the turning of motor shafts to generate digital position and motion information. Whether incremental or absolute, magnetic or optical, rotary encoders track motor shaft rotation to generate digital position and motion information. Their use proliferates in industrial and commercial designs. Rotary encoders track motor shaft movement for myriad pieces of industrial equipment and commercial devices. For industrial applications, incremental encoders (used when only relative position is needed, or cost an issue) are typically used with ac induction motors. In contrast, absolute encoders (which give a different binary output at each position, so shaft position is absolutely determined) are often paired with permanent-magnet brushless motors in servo applications. Often, encoder feedback is used to ensure synchronization of the motor stator and rotor positions to drive-supplied current, so current is applied to the windings when the rotor magnets are within a proper position range (to maximize torque.)
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Ultrasonic sensors Ultrasonic sensors transmit ultrasonic waves from its sensor head and again receives the ultrasonic waves reflected from an object. By measuring the length of time from the transmission to reception of the sonic wave, it detects the position of the object.
They are devices that use electrical–mechanical energy transformation to measure distance from the sensor to the target object. Ultrasonic waves are longitudinal mechanical waves which travel as a sequence of compressions and rarefactions along the direction of wave propagation through the medium. Apart from distance measurement, they are also used in ultrasonic material testing (to detect cracks, air bubbles, and other flaws in the products), Object detection, position detection, ultrasonic mouse, etc. * These sensors are categorized in two types according to their working phenomenon – piezoelectric sensors and electrostatic sensors. **An ultrasonic sensor consists of a transmitter and receiver which are available as separate units or embedded together as single unit. Ref: http://machinedesign.com/sensors/basics-rotary-encoders-overview-and-new-technologies-0
Questions on Sensors 1. Write any two applications for each of the following sensors: i) Displacement sensors ii) Proximity sensors iii) Ultrasonic sensors 2. What is the function of ground terminal in a 3 pin Adopter? 3. What is sensor? Mention the types of sensor used in the following applications i) Flatness measurement ii) Sensor which detects dielectric materials iii) Sensors used in aviation
