Ans: (c). 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. 2.8, is usu­ally actuated by current flow­ing in a single coil wound on a magnetic structure contain­ing an air gap. Plagiarism Prevention 5. d) Avoid harmonics Relay Voltage Rating Question. September 18, 2016 by admin. A torque is produced due to the interaction between the rotating flux and the induced current which causes the rotation of the cylinder. C. both of the above. 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. d. None of these. The primary current induces emf in the secondary and so circulates a current I2 in it. The higher the time multiplier setting the greater is the operating time. b) Over voltage (2.2). 1. d) Moving coil The torque produced in shaded pole structure induction type relay is . VA burden depends upon rating. b) Minority carriers In which of the following device the base resistors are not added in the package but added externally? (2.2): (i) The net force is same at every instant as the term to r is not involved in the expression for the force developed. b) Induction cup The time setting can be changed by changing the relative position of contacts by adjusting the length of travel of moving contacts. Some question about a relay data-sheet. Content Filtration 6. This types of relays work on the same principle of induction motor. Within built software with predefined values: Measuring elements/ Hardware: Induction disc, electromagnets, induction cup, balance beam: R, L, C, transistors, analogue ICs comparators What is a Static Relay Definition Advantages. The moving element acts as a carrier of rotor currents, where as the magnetic circuit is completed through stationary magnetic elements. Answer: Option D . The rotating field induces currents in the cup causing it to rotate in the same direction. Generally four pole and eight pole design are available. The quantities shown in Fig. Choosing correct relay for LED power supply rating . 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. A. b) Avoid overheating of transformer A relay is a switching device as it works to isolate or change the state of an electric circuit from one state to another. Ans: (d), a) Over load faults A rotating field is produced by the two pairs of coils shown in Fig. Induction Cup Relay Working Principle Construction and Types Over Current Relay Working Principle Types Differential Relay Thermal Relay … a) Earth faults a) Current b) Power c) Voltage d) Impedance Ans: (d) 20. 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. The operating time characteristic depends on the type of structure. The rotation depends on the … c) Provide artificial earthing Since the two forces (F1 and F2) developed are in opposition, as illustrated in Fig. It is a high speed induction relay since inertia is less. The time-current characteristics of induction relays are inverse characteristics, as shown in Fig. C. Induction type structure . b) Bound electrons are always present in the semiconductor. In this relays transistors and IC’s been used: They use microprocessor. Economics of Operation page-2, Objective Type Question or MCQ of B. The rotating field induces currents in the cup causing it to rotate in the same direction. Bottom: The same relay photographed from the front.Suppose you want to build an electronically operated coolingsystem that switches a fan on or off as your room temperaturechanges. c) Shaded pole 2.9, i.e., the time reduces as current increases. Induction cup relays operate on the same principle as the induction motor. Modern induction disc relays are robust and reliable. It is of the order of 2.5 VA. designed to respond; operating characteristics of a given manufacturer's line of such relays. Account Disable 12. • Two suitable CTs are connected in series as shown with the help of pilot wires. 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. a) Inner electrons are always present in the semiconductor. b) In two zones When these coils are excited, a rotating magnetic field is produced. d) The saturation voltage VCE for silicon transistor is lower than germanium transistor. Generally four pole and eight pole design are available. d) All of these b) Alternator Image Guidelines 4. i.e., the driving torque varies as the square of the current flowing through the relay coil. c) The saturation voltage V CE for silicon transistor is same as that for germanium. Most of the modern induction relays are of this type. 0. A. current. Induction cup type relay can be considered as a different version of induction disc type relay. c) PUT These are found in all sorts of devices. B. This accuracy is not a consequence of the induction principle, but because such relays invariably employ jewel bearings and precision parts that minimize friction. 2.8. Induction type relays are employed extensively for protection against overloads, short circuits, and earth faults on transmission/distribution lines and in industrial plants. Induction Cup Relay • Modern induction cup relays have 4 or more poles • The relays can be responsive to voltage and current • The double actuating quantity relay can be responsive to both voltage and current • The operating time characteristics depends on the type of structure • Modern Induction cup relay may have an operating time of 0.010 second . 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 Protection. It is most significant. Accordingly, induction cup relays can be designed to produce maximum torque when the angle θ = 0 or 30 o, 45 o or 60 o. 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. Polarizing and operate quantities were applied individually to the two windings. b) Short circuits 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. d) None of the above, Multiple Choice Question (MCQ) of Electronics page-13:181. Pages 2. Various quantities are shown at an instant when both fluxes are directed downward and are increasing in magnitude. The relays produce maximum torque when θ = 45 o or 60 o, are used as directional protection relay. The control torque is provided with the help of a control spring attached to the disc spindle. Questions about Relays. d) Alloys, Multiple Choice Question (MCQ) of Electronics page-14:196. Such relays are comparable in accuracy to meters employed for registration of electrical energy consumption. b) Interphase faults Induction cup relay working principle construction. View Answer. 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