Torque is developed by electromagnetic induction principle. Economics of Operation page-6, Objective Type Question or MCQ of B. the two pairs of coils are displaced by 90 o. View Answer. Ans: (d), a) Over load faults A torque is produced due to the interaction between the rotating flux and the induced current which causes the rotation of the cylinder. This is necessary to reduce to a minimum the over-run of the disc in case the current or voltage providing the driving torque stops before the operation has been completed. The rotation depends on the … The relay has two, four or more electromagnets energized by the relay coils. • The relay operating coil is connected between the mid-points (equipotential points) of the pilot wire. Ans: (c). Image Guidelines 4. To understand this concept easily, it is better to know about settings of the Electromechanical Relays. The conduction in JEFT is always by the Burden (of a relay) - Load impedance imposed by a relay on an input circuit expressed in ohms and phase angle at specified conditions. Disclaimer 8. If this circuit is opened, no torque will be developed and thus the relay can be made inoperative. b) The saturation voltage VCE for germanium transistor is more than silicon transistor. a) Current b) Power c) Voltage d) Impedance Ans: (d) 20. Relays detect and locate faults by measuring electrical quantities in the power system which are different during normal and intolerable conditions. Protective Relays: Detect and respond to abnormal conditions in a circuit Backup Relays: Provide backup protection for more sensitive relays and have a time delay Auxiliary Relays: Used as the muscle to trip a circuit or a piece of equipment Control Relays: Take a relatively small amount of power and use it either to signal or control a large amount of power. The dc offset may affect fast relays. The static iron core is placed between the electromagnet as shown in the figure below. School COMSATS Institute of Information Technology, Islamabad; Course Title PAK STUDIE HUM 102; Uploaded By JusticeCrabPerson1718. Copyright 10. High, low and adjustable speeds are possible in induction type relays. B. Watt hour meter structure . 2.6 may be expressed as –, where, θ is the angle by which ɸ2 leads ɸ1. Air gap of magnetic path. It is most significant. VA burden depends upon rating. It consists of an E-shaped electromagnet and a U-shaped electromagnet with a disc free to rotate in between. The higher the time multiplier setting the greater is the operating time. Protective Relays Their Theory and Practice Google Books. Different Types of Relays Elements: The Important Different Types of Relays Elements or also called Electromagnetic Types are Induction Disc Relay Induction-cup Relays Moving Coil Relays Hinged Armature Relays Polarized Moving Iron Relays Moving Iron and Balanced Beam Relays 1.Induction Disc Relay: The shaded pole type gives the most effective form of an electromagnet since … Electromagnetic-induction relays use the principle of the induction motor whereby torque is developed by induction in a rotor; this operating principle applies only to relays actuated by alternating current, and in dealing with those relays we shall call them simply "induction-type" relays. The rotation depends on the direction of rotation of the field and the magnitude of the applied voltage and/or currents and the phase angle between them. Pickup - The action of a relay as it makes a designated response to progressive increase of input. The movement of the rotor … Ans: (c), a) Inter-turn faults Economics of Operation page-2, Objective Type Question or MCQ of B. Electromagnetic induction relays are the most widely used relays for protective relaying purposes involving only ac quantities. Relays may be classified as to which kind of physical quantity the sensing element respond to and may be classed as electrical (actuated by some electrical quantity such as current, voltage, power etc. 2.8, is usu­ally actuated by current flow­ing in a single coil wound on a magnetic structure contain­ing an air gap. All the relays respond to one or more electrical quantities like voltage or current such that they open or close the contacts or circuits. These are found in all sorts of devices. If the shading coils are short circuited by a contact of some other relay, torque will be developed; but, if the coils are open circuited, no torque will be developed because there will be no phase-splitting of the flux. The air-gap flux produced by the actuat­ing current is split into two fluxes displaced in time and space by a so-called shading ring, generally of copper, that encircles part of the pole face of each pole, as shown in Fig. A stationary iron core is placed between these electromagnets (four in number) as illustrated in Fig. You could use some kind of electronic thermometer circuit tosens… Ans: (b), a) Permanent moving magnet Each flux induces voltage around itself in the rotor, and currents flow in the rotor under the influence of the two voltages. b) Interphase faults The rotor is a hollow metallic cylindrical cup which is free to rotate in the gap between the electromagnets and the stationary iron core. a) Semiconductors The two fluxes ɸ1 and ɸ2 induced in upper and lower magnets respectively differing in phase by angle θ will develop a driving torque on the disc proportional to ɸ1. In which of the following device the base resistors are not added in the package but added externally? Electromagnetic Induction. ɸ2 sin θ. 1955 Fig.3. Such relays are comparable in accuracy to meters employed for registration of electrical energy consumption. In electromagnetic attraction relay plunger is drawn to the solenoid or an armature is attracted to the poles of the electromagnet. d) Avoid harmonics C. both of the above. b) Avoid overheating of transformer d) All of these 1. The ratio of reset to pick­-up is inherently high in case of induction relays as compared to attraction armature relays as their operation does not involve any change in the air gap of the magnetic circuit as it is in the case of latter. i.e., the driving torque varies as the square of the current flowing through the relay coil. Inductance changes in DC relay coils. b) Aped & sensitivity The control torque is provided with the help of a control spring attached to the disc spindle. The IEEE defines protective relays as: “relays whose function is to detect defective lines or apparatus or other power system conditions of an abnormal or dangerous nature and to initiate appropriate control circuit action ”. Answer Explanation Related Ques: ANSWER: Number of ampere turns. c) Inter turn faults In case of electro-magnetic induction, principle of operation is similar to induction motor. Actuating force is developed on a moving element, that may be a disc or other form of rotor of non-magnetic current-conducting material (such as aluminium), by the interaction of electromagnetic fluxes … a) UJT d) None of these A. Pages 2. Terms of Service 7. The relay disc is so shaped that as it turns towards the pick-up position (closing of contacts), there is increase in the area of the disc between the poles of the actuating structure which causes increase in eddy currents and, therefore, increase in electrical torque that just balances the increase in the control spring torque. The shaded-pole structure, il­lustrated in Fig. Prohibited Content 3. Join The Discussion. The primary winding carries relay current I1 while the secondary winding is connected to the windings of U-shaped electromagnet (Fig. Principle of Induction Type Relays. From torque-weight ratio point of view the movable element should be of aluminium alone. C. impedance. Electromagnetic induction relays are the most widely used relays for protective relaying purposes involving only ac quantities. The relay which works on the principle of electromagnetic induction is known as the induction cup relay. The construction of this relay is similar to the watt-hour meter commonly used everywhere. c) Provide artificial earthing The rotor is a hollow metallic cylindrical cup which is free to rotate in the gap between the electromagnets and the stationary iron core d) Inner and bound electrons are always present in the semiconductor. Introduction to Static Protection Relays. The moving element acts as a carrier of rotor currents, where as the magnetic circuit is completed through stationary magnetic elements. a) The saturation voltage V CF of silicon transistor is more than germanium transistor. Figure 2.6 illustrates how force is developed in a section of a rotor that is pierced by two adjacent ac fluxes. Eletro-mechanical relays operate by two principles. a) The saturation voltage VCF of silicon transistor is more than germanium transistor. 2. c) Overhead lines 2.10). Economics of Operation page-3, Objective Type Question or MCQ of B. b) CUJT The action of a relay under the influence of such a force is positive and free from vibration. ANSWER: Induction cup structure. The shape of the disc usually is that of a spiral. Induction cup relays operate on the same principle as the induction motor. Generally four pole and eight pole design are available. AC relay coil current calculation. 1. Using AC rated relay in DC applications. 2.8. This is known as time multiplier setting. When these coils are excited, a rotating magnetic field is produced. a) Earth faults In the center was a magnetic core with a movable cup with contacts and a spring to provide reset tension. The different types of structures that have been used for obtaining the phase difference in the fluxes and hence the operating torque in induction relays are: (ii) Watt-hour meter or double winding structure (disc type) and. Electrical Engineering, Devices, Relays, Electromagnetic Induction Relays. Watt-hour meter type induction disc relay gives the same results as given by a shaded pole type. b) Power This accuracy is not a consequence of the induction principle, but because such relays invariably employ jewel bearings and precision parts that minimize friction. Economics of Operation page-1, Objective Type Question or MCQ of Power System Protection page-8, Objective Type Question or MCQ of Power System Protection page-7, Objective Type Question or MCQ of Power System Protection page-6, Objective Type Question or MCQ of Power System Protection page-5, Objective Type Question or MCQ of Power System Protection page-4, Objective Type Question or MCQ of Power System Protection page-3, Objective Type Question or MCQ of Power System Protection page-2, Objective Type Question or MCQ of Power System Protection page-1, Multiple Choice Question (MCQ) of Alternator and Synchronous Motors page-11, Multiple Choice Question (MCQ) of Alternator and Synchronous Motors page-10, Multiple Choice Question (MCQ) of Alternator and Synchronous Motors page-9, Multiple Choice Question (MCQ) of Alternator and Synchronous Motors page-8, Multiple Choice Question (MCQ) of Alternator and Synchronous Motors page-7, Multiple Choice Question (MCQ) of Alternator and Synchronous Motors page-6, Multiple Choice Question (MCQ) of Alternator and Synchronous Motors page-5, Multiple Choice Question (MCQ) of Alternator and Synchronous Motors page-4, Multiple Choice Question (MCQ) of Alternator and Synchronous Motors page-3, Multiple Choice Question (MCQ) of Alternator and Synchronous Motors page-2, Multiple Choice Question (MCQ) of Alternator and Synchronous Motors page-1. c) External Faults Description. The driving torque is given as –. Higher current setting will require smaller number of turns so as to give fixed ampere-turns required for developing the minimum torque for the movement of the disc. Some question about a relay data-sheet. y 1957 I w. E. GLASSBURN 2,792,531 . Modern induction disc relays are robust and reliable. A modern induction disc relay will have an over-run of not more than 2 cycles on interruption of 20 times the setting quantity. A stationary iron core is placed between these electromagnets to decrease the air gap without increasing inertia. Choosing correct relay for LED power supply rating . Therefore, such relays are very fast in operation and may have an operating time of less than 0.01 second. The time setting can be changed by changing the relative position of contacts by adjusting the length of travel of moving contacts. b) In two zones FUNDAMENTALS OF POWER SYSTEM PROTECTION. • Two suitable CTs are connected in series as shown with the help of pilot wires. Obviously the force developed will be maximum when phase angle θ is 90°. c) Holes The flux ɸ2 induced in the U-shaped or lower magnet by the current in the secondary winding of the E-shaped or upper magnet will lag behind flux ɸ1 by an angle θ. Which of the following statement is correct? A control spring and the back stop or closing of the contacts carried on an arm are attached to the spindle of the cup so as to prevent the continuous rotation. b) Over voltage Most of the modern induction relays are of this type. Electro-magnetic attraction and electro-magnetic induction. The current produced by one flux reacts with the other flux, and vice versa, to produce forces that act on the rotor. Answer: Option D . d) Impedance A. delayed. D. all of the above. 2. 0. These relays operate on the simple principle of split-phase induction motor. The rotating field induces currents in the cup causing it to rotate in the same direction. c) The saturation voltage VCE for silicon transistor is same as that for germanium. d) All of these B. voltage. Induction cup type relay are used where, very high speed operation along with polarizing and/or differential winding is requested. which results in a current due to short circuit nature of the rotor. d) C.T., P.T. All the relays operate in response to one or more electrical quantities either to close or to open contacts. Protective Relays Principles amp Practices. Ratio of reset to pick-up is high (above 95%) because operation does not involve any change in air gap. The relays produce maximum torque when θ = 45 o or 60 o, are used as directional protection relay. In order to produce an operating torque, the two fluxes must have a phase difference between them. They are not used with DC quantities owing to the principle of operation. Ans: (d), a) Over voltage c. Adjustable back stop. The rotating field induces currents in the cup causing it to rotate in the same direction. The relay has two or more electromagnet which is energized by the relay coil. Explanation: No explanation is available for this question! c) The saturation voltage V CE for silicon transistor is same as that for germanium. It may be assumed with negligible error that the paths in which the rotor currents flow have negligible self-inductance, and therefore rotor currents are in phase with their respective induced voltages. These relays have inverse-time characteristics. Top: Looking straight down, you can see the spring contacts on the left, the switch mechanism in the middle, and the electromagnet coil on the right. The rotor cuts the magnetic field and an emf is induced in the rotor. An important feature of relay of this type is that its operation can be controlled by opening or closing the secondary winding circuit. Which of the following statement is true? RELAYS Filed Oct. 7. The working principle of both type of relays are more or less some. (2.2). In induction type directional over current relay the driving torque is due to interaction of magnetic fields; In an induction motor if the flux density is reduced to one-half, of its normal value then the torque will; In a single-phase induction motor when the rotor is stationary and voltage is applied to the stator, then Huge Collection of Essays, Research Papers and Articles on Business Management shared by visitors and users like you. This preview shows page 1 - 2 out of 2 pages. c) Insulators (iv) The direction of net force and hence the direction of motion of movable element depends upon which flux is leading. Within built software with predefined values: They use microprocessor. ), thermal (actuated by heating effect), optical, acoustical, and other types of relays. It is a high speed induction relay since inertia is less. The E-shaped electromagnet carries two windings; the primary and the secondary. B. Report a Violation 11. The following points may be noted from Eq. This fact does not depend upon the assumptions made in arriving at Eq. D. Single induction loop structure View Answer. It is of the order of 2.5 VA. The operating time characteristic depends on the type of structure. Induction Cup Relay Working Principle Construction and Types Over Current Relay Working Principle Types Differential Relay Thermal Relay … The advantage of this type of construction is that it can provide larger phase angle between ɸ 1 and ɸ 2 and thus higher torque, being proportional to sin θ. In this relays transistors and IC’s been used: They use microprocessor. Induction cup relay is operated due to changes in. The quantities shown in Fig. Induction Relays. [gravityform id="1" title="false" description="false" ajax="true"]. Multiple Choice Question (MCQ) of Electronics page-16:226. Polarizing and operate quantities were applied individually to the two windings. • Induction cup relays were widely used for distance and directional relays. Multiple Choice Question (MCQ) of Electronics page-17:241. Content Guidelines 2. There are really only two fundamentally different operating principles: Electromagnetic Attraction, and. B. instantaneous. 1. Induction cup relay working principle construction. Ans: (a), a) Current Wiring up the SRD-05VDC-SL-C to an Arduino or Arduino-like microcontroller. The primary current induces emf in the secondary and so circulates a current I2 in it. 2.9, i.e., the time reduces as current increases. d) Alloys, Multiple Choice Question (MCQ) of Electronics page-14:196. b) Bound electrons are always present in the semiconductor. ... scheme is supposed to respond only internal faults, and restrain from tripping on external or through faults. These relays operate on the simple principle of split-phase induction motor. Induction cup type relay are used where, very high speed operation along with polarizing and/or differential winding is requested. Multiple Choice Question (MCQ) of Electronics page-17:241. September 18, 2016 by admin. b) Alternator Ans: (d), a) Speed & reliability c) Adequateness & selectivity D. none of the above . C. Induction type structure . Plagiarism Prevention 5. relays in which the interaction is between a magnetic field and current induced thereby in a conductor. Relays Step-down transformer Switchgear ⇒ In Railway applications ____ circuit breaker is used. The two rings have currents induced in them by the alternating flux of the electromagnet and the magnetic fields developed by these induced currents cause the flux, in the portions of the iron surrounded by the rings to lag in phase by 40° to 50° behind the flux in the un-shaded portions of the pole. c) Independent of zone b) Minority carriers The accuracy of an induction type relay recommends it for protective relaying purposes. Account Disable 12. Magnetic circuit breaker has _____ trip action. d) Magnetizing current A. Shaded pole structure . Content Filtration 6. b. b) Heavy Loads Induction cup type relay can be considered as a different version of induction disc type relay. Response of Tower-Like Structures to Wind Loading | Wind Engineering, Unconventional Machining Processes: AJM, EBM, LBM & PAM | Manufacturing, Material Properties: Alloying, Heat Treatment, Mechanical Working and Recrystallization, Design of Gating System | Casting | Manufacturing Science, Forming Process: Forming Operations of Materials | Manufacturing Science, Generative Manufacturing Process and its Types | Manufacturing Science. Relay Voltage Rating Question. The most efficient torque producing actuating structure for induction type relays is . The relays which are such designed, that, they produce maximum torque at θ = 0, is P induction cup power relay. e) Holes and electrons simultaneously, Objective Type Question or MCQ of Electrical Circuits and Magnetic Fields page-20, Objective Type Question or MCQ of Electrical Circuits and Magnetic Fields page-19, Objective Type Question or MCQ of Electrical Circuits and Magnetic Fields page-18, Objective Type Question or MCQ of Electrical Circuits and Magnetic Fields page-17, Objective Type Question or MCQ of Electrical Circuits and Magnetic Fields page-16, Objective Type Question or MCQ of Electrical Circuits and Magnetic Fields page-15, Objective Type Question or MCQ of Electrical Circuits and Magnetic Fields page-14, Objective Type Question or MCQ of Electrical Circuits and Magnetic Fields page-13, Objective Type Question or MCQ of Electrical Circuits and Magnetic Fields page-12, Objective Type Question or MCQ of Electrical Circuits and Magnetic Fields page-11, Objective Type Question or MCQ of Electrical Circuits and Magnetic Fields page-10, Objective Type Question or MCQ of Electrical Circuits and Magnetic Fields page-9, Objective Type Question or MCQ of Electrical Circuits and Magnetic Fields page-8, Objective Type Question or MCQ of Electrical Circuits and Magnetic Fields page-7, Objective Type Question or MCQ of Electrical Circuits and Magnetic Fields page-6, Objective Type Question or MCQ of Electrical Circuits and Magnetic Fields page-5, Objective Type Question or MCQ of Electrical Circuits and Magnetic Fields page-4, Objective Type Question or MCQ of Electrical Circuits and Magnetic Fields page-3, Objective Type Question or MCQ of Electrical Circuits and Magnetic Fields page-2, Objective Type Question or MCQ of Electrical Circuits and Magnetic Fields page-1, Objective questions and answers or MCQ of Electrical Machines page-22, Objective questions and answers or MCQ of Electrical Machines page-21, Objective questions and answers or MCQ of Electrical Machines page-20, Objective questions and answers or MCQ of Electrical Machines page-19, Objective questions and answers or MCQ of Electrical Machines page-18, Objective questions and answers or MCQ of Electrical Machines page-17, Objective questions and answers or MCQ of Electrical Machines page-16, Objective questions and answers or MCQ of Electrical Machines page-15, Objective questions and answers or MCQ of Electrical Machines page-14, Objective questions and answers or MCQ of Electrical Machines page-13, Objective questions and answers or MCQ of Electrical Machines page-12, Objective questions and answers or MCQ of Electrical Machines page-11, Objective questions and answers or MCQ of Electrical Machines page-10, Objective questions and answers or MCQ of Electrical Machines page-9, Objective questions and answers or MCQ of Electrical Machines page-8, Objective questions and answers or MCQ of Electrical Machines page-7, Objective questions and answers or MCQ of Electrical Machines page-6, Multiple Choice Question (MCQ) of Protective Relays page-4, Multiple Choice Question (MCQ) of Protective Relays page-3, Multiple Choice Question (MCQ) of Protective Relays page-2, Multiple Choice Question (MCQ) of Protective Relays page-1, Multiple Choice Question (MCQ) of Circuit Breaker page-3, Multiple Choice Question (MCQ) of Circuit Breaker page-2, Multiple Choice Question (MCQ) of Circuit Breaker page-1, Objective Type Question or MCQ of B. 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