Power factor of the magnetizing component of a transformer is mcqs. If the resistance of the primary winding is 0.

A 3300/300V single phase transformer gives 0. Parallel circuits use the voltage as the reference phasor and series circuits use the current , as in each case the reference phasor is common to all of the Explanation: If transformer is considered as a magnetically coupled circuit, then by fundamental Kirchoff’s voltage law one can find equations for applied voltage, current and inductance of each coil of a transformer, considering the direction of current, which implies negative sign. May 22, 2024 · From the above two errors, it can be seen that the ratio and phase angle errors depend upon the no-load current (i. Find magnetizing working components of no- load primary Current. Explanation: The maximum value of power factor is 1. 6A and 60W as ammeter and wattmeter readings when supply is given to the low voltage winding and high voltage winding is kept open. Unity C. In electrical engineering, a transformer is a passive component that transfers electrical energy from one electrical circuit to another circuit, or multiple circuits. From the phasor we can observe that magnetizing component of no-load current lags the applied voltage by 90°. V o / I o, V o / I c d. A transformer is efficient device for the reason being: It uses capacitive coupling Mar 15, 2021 · This article lists 100 Transformer MCQs for engineering students. Ia Vs If with constant shaft load B. Thus due to Power factor is also defined as the ratio of the resistance to the impedance of an AC circuit. V o / I c, V o / I o View Answer / Hide Answer Jan 1, 2013 · The operating conditions of the transformer connected to the inverter are particularly unknown for each solar power plant; thus, the transformer will be subject to a particular harmonic content Nov 24, 2016 · The method is based on magnetization current, harmonic content and power factor evaluated of the transformer no-load current with high magnetic flux density subjected. If the primary winding has 550 turns, calculate (a) the magnetising component of no-load current (b) the iron loss (c) the maximum value of the flux in the core. The secondary winding supplies a load of 4 A at lagging power factor of 0. It has 2 main parts electric and magnetic for controlling the VI flow. The input power to a transformer is 100kW. I 0 tan Φ 0 View Answer / Hide Answer Aug 12, 2024 · ϕ R is the receiving end power factor angle. In order to improve the power factor of this circuit, the remedy is to connect such equipment in parallel with the load which takes a leading reactive component and partly cancels the lagging reactive component of the load. 4. Mechanical loss. 2 to 0. The equivalent circuit for a 200/400-V step-up transformer has the following parameters referred to the low-voltage side: The transformer is supplying a load of 10 A at a power factor of 0. power factor D. always leading d. find (a) the iron loss component of no load current (b) the magnetizing component of no load current (c) no load power factor. 2 power factor lagging and the secondary supplies a current of 120 A at a power factor of 0. Jul 4, 2021 · Power transformers are intended to be as efficient as possible under full load since they are used at full load. The power factor of capacitive circuits is. I 0 tan Φ 0 View Answer / Hide Answer The no-load test is performed to determine the no-load losses or core losses as well as the turns ratio, no-load currents, magnetization components and core loss components of the transformer. Hysteresis loss. The power factor is the parameter that defines the relative phase displacement between current and voltage phasors. 𝟐𝟐 = 𝑽𝑽. 19. Answer: (b) The magnetizing component of the stator exciting current is increased. It is used to find. A power transformer is a static machine used for transforming power from one circuit to another without changing the frequency. What is Current Transformer (CT) ? A C. . 95 leading; Correct answer: 3. power C. com The Test: Transformer of Electrical Machines questions and answers have been prepared according to the Electrical Engineering (EE) exam syllabus. If the transformer iron core did not saturate, the magnetizing current (Im), generated by the flux, would be sinusoidal in shape and in phase with the flux. Impedance is the effective resistance of an electric circuit or component to alternating current. 919A, 184W May 26, 2021 · Ideally a transformer draws the magnetizing current, lags primary applied voltage by 90°. For convenience, the supply is connected to the LV side of the transformer and the HV side of the transformer is left open. In a power system, what is the term for the resistance encountered by alternating current due to the capacitive and inductive reactance of a Oct 29, 2015 · A transformer when connected to a 230V, 50Hz supply, under no load draws a current of 4A at a power factor of 0. Answer (Detailed Solution Below) Option 3 : Eddy current loss. The primary and secondary of a transformer are ________ coupled but _______ connected. Assume idea operation and find: May 26, 2024 · Clarification: As the power factor is decreased, Vs leads in phase while V p decreases in phase. where cosθ 0 is the no-load power factor. Controlling power factor Aug 13, 2024 · Voltage Regulation of Transformer at Unity Power Factor. Explanation: The most economical power factor for a consumer is usually 0. 0. power factor vs If D. Power transformers are independent of P. While conducting short-circuit test on a transformer which side is short circuited? a) High voltage side b) Low voltage side c) Primary side d) Secondary side View Answer It has two components: I M, the magnetizing component which flows 90° lagging behind induced voltage E s; and I e, the core-loss current which is in phase with E s. Definite power factor C. Transformer inrush current or magnetization inrush current is a transient input current drawn by a transformer during its energization. (a) Circuit of a transformer with output open-circuited (b) Approximate phasor diagram Figure 2. In the case of transformer Buchholz relay is used to protect from . 39. 6 A and 60 W as ammeter and wattmeter readings when supply is given to the low voltage winding and high voltage winding is kept open, find 1) Power factor of no-load current 1) Magnetizing component iii) Iron los component 24. The maximum value of power factor is: 0; 0. Such a current could also be the exciting current or no-load current in a transformer. for unbalance load C. Demo Classes Available* Enroll For Free Now. 𝟏𝟏 = 𝑽𝑽. V o / I c, V o / I m b. Peak value / RMS value. What role do current transformers play in protective relaying systems? A. When a delta connected primary of a 3-phase transformer is connected to 3-phase supply (a) magnetizing current in phase winding will carry third harmonics but line current will be free from it. 206. Jul 24, 2024 · The power (volt-ampere) input to the transformer is equal to the power output from the transformer. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests . 114. After completion of the few cycles, active Jul 21, 2024 · Get Instrument Transformers Multiple Choice Questions (MCQ Quiz) with answers and detailed solutions. Free essays, homework help, flashcards, research papers, book reports, term papers, history, science, politics 4) A transformer when connected to a 230V, 50Hz supply, under no load draws a current of 4A at a power factor of 0. secondary of a voltage transformer when the primary is energized with the rated voltage. Power transformers are not directly linked to the consumer side; therefore, it causes very less load fluctuation. 2 Jun 4, 2015 · Delta-Delta Connection in Three Phase Transformers - MCQs wi Star-Star Connection in Three Phase Transformer - MCQs with Principle of Operation in Three Phase Transformers - MCQs wi Constant Current, Audio Frequency & Pulse Transformers - MCQ Constant Voltage Transformers - MCQs with Answers; Auto Transformers - MCQs with Answers Jan 20, 2020 · A transformer core having air gap has expected to have: Decreased hysteresis losses; Increased magnetizing current; Increased eddy currents; None of these; Correct answer: 2. This set of Electrical Machines Multiple Choice Questions & Answers (MCQs) focuses on “Transformer Construction”. This is helpful for users who are preparing for their exams, interviews, or professionals who would like to brush up on the fundamentals of the Instrument Transformer. 95; 1; Correct answer: 4. D. Bar type; Wound type; Wound-type Current Transformer: The transformer’s primary winding is physically connected in series with the conductor that carries the measured current flowing in the circuit. Thus, one will have maximum efficiency if load is nearly equal to full load and at unity power factor. Ammeter. The magnetizing current of a transformer is usually small because it has Jul 13, 2020 · Assuming a sinusoidal flux wave, Figure 1 shows the derived magnetizing current-time curve. The first power Subsequently, the low input power factor does not negatively impact the overall supply components (transformer, wiring, etc. 31. Download these Free Instrument Transformers MCQ Quiz Pdf and prepare for your upcoming exams Like Banking, SSC, Railway, UPSC, State PSC. This is helpful for users who are preparing for their exams, interviews, or professionals who would like to brush up on the fundamentals of Transformer. 𝟏𝟏. 8 lagging c. How is the Magnetizing component with respect to the voltage? a) the magnetizing component is in phase with the voltage b) the magnetizing component is 90° leading the voltage c) the magnetizing component is 90° lagging the voltage d) the magnetizing component is 90° out of phase with the voltage View Answer The no-load current of a transformer is 10 A at a power factor of 0. Jul 15, 2024 · The power factor of an induction motor under no-load conditions is typically: A) Leading Transformers MCQs; Electric and Magnetic Field Analysis MCQs; May 21, 2024 · Power factor. 𝟐𝟐. These transformers with low range ampere meters are used to measure the current in the high voltage circuits. Aug 13, 2024 · Get Transformer Tests Multiple Choice Questions (MCQ Quiz) with answers and detailed solutions. neither A nor B D. Neglecting impedance drop (a) both of them are in phase with the supply voltage. 3; 0. But the transformer also has core loss current component which will be in phase with applied voltage. , magnetizing and loss component of exciting or no-load current), impedance (i. 8 lagging D. These distortions can cause an increase in reactive power and reduce the power factor. A type of generating station B. Power factor of the transformer at no load . 5. Phase Angle Meter. Circuit for no-load test. Equivalent resistance = 0. Now find the power factor and the active and reactive powers Ans Ans Ans Ideal Transformer Calculations Lesson 8_et332b. FREE. These are generally classified as (i) Current transformer – large alternating currents can be measured (ii) Potential transformer – High voltages can be measured May 23, 2024 · Power factor improvement using the static capacitor: Consider an inductive load taking a lagging current 'I' at a power factor cos ϕ 1. A transmission line D. Current amplification C. AC only. Definite frequencies Aug 22, 2023 · A current transformer has a rating of 100/5 A. Current which takes into account of core or iron losses (eddy +Hysterisis loss) (watt full current) Jul 15, 2024 · In a transformer, the maximum power transfer occurs when: A) The primary and secondary windings have the same number of turns B) The primary voltage is higher than the secondary voltage The no-load current of a transformer is 15 at a power factor of 0. For a transformer, operating at constant load current, maximum efficiency will occur at (a) 0. Considering the transformer to be ideal and overall system as lossless and power system as 1, what is the power used; 3 The no-load power factor of transformer is small due to which of following reason Mar 31, 2021 · During energisation of the transformer, normally active power is nearly zero although during energising the transformer under an internal fault, huge active power is consumed by the circuit , although during the first cycle of the inrush, huge amount of active power was disbursed for a few cycles. May 26, 2024 · (b) output voltage fluctuation with power factor is least (c) difference between primary and secondary voltage is least (d) difference between primary and secondary voltage is maximum Answer: a. Figure 1. We can employ transformers for a power range of May 29, 2015 · Q6. The magnetizing current (I m ) and core loss (P c ) is equal to a. India's Super Teachers for all govt. Generator transformers are _____ a) Step-up transformers b) Step-down transformers c) Auto-transformers d) One-one transformers View Answer An O-core transformer consisting of two coils of copper wire wrapped around a magnetic core. 5-7 along with the flux wave Φ and induced voltage wave e Jun 17, 2024 · Power transformer. Power Transformer Protection and Faults; Transformers Insulation Materials in Oil-Immersed & Dry Type T/F; Transformers Fire Protection System – Causes, Types & Requirements; What is the Difference Between Power Transformers and Distribution Transformers? Transformer Phasing: The Dot Notation and Dot Convention Question: at a and A 2,200/250-v transformer takes 0. No-load current is a vector summation of working component I W and magnetizing component I μ. For an alternating voltage form factor is a. PF = cos 0° = unity Dec 3, 2018 · Sometimes termed ‘transactors’ and ‘quadrature current transformers’, this form of current transformer has been used as an auxiliary component of traditional pilot-wire unit protection schemes in which the outputs into multiple secondary circuits must remain linear for and proportional to the widest practical range of input currents. Draw the approximate equivalent circuit diagram. Thus the phase angle reduces with the decrease in power factor (lagging). C. 8. The heat run test could, therefore, be conducted on the two transformers, while only losses are supplied. All the Transformer Questions & Answers given below include a hint and a link wherever possible to the relevant topic. 23 shows the no-load phasor diagram of a practical transformer. The magnetizing current (I m ) and core loss (P c ) is equal to - Published on 29 Oct 15 Mar 30, 2022 · The current transformer are generally classified in two types. Alternators are usually designed to generate. A power transformer can increase or decrease the voltage and current, hence can be used as either a step-up or step-down transformer. These transformers are used to isolate the instruments from high current and high voltage A. May 22, 2021 · Answer: (A) lags behind applied voltage somewhat less than 90° Explanation: As the winding of the transformer is inductive the magnetizing current in it lags behind the primary applied voltage by exactly 90° but there is a core loss component that will be in phase with applied voltage. May 26, 2024 · 29. The joints in the transformer core laminations are staggered so as to (a) avoid cmitinuous gap causing increase in magnetizing current. Mean value / RMS value c. Sep 3, 2016 · This Magnetizing Current lags the Stator Voltage V 1 by 90°. Explanation: Similar to normal transformers power transformers are also designed to get maximum efficiency at load which is near to the full load of a transformer specified. Which is improve the power factor May 6, 2024 · For a consumer the most economical power factor is usually. Therefore, the ratio between them will be 1, and hence power factor is a unit less and dimensionless quantity. All the Power Systems Questions & Answers given below includes solution and link wherever possible to the relevant topic. I S is the sending end current. Zero B. In other words, Im is the magnetizing current and is responsible for the production of flux, while Ii is the core-loss current responsible for the active power being drawn from the 3. The first component is called the displacement power factor: 2 ( × Ü æ ã= É Ï, Â, Ý Ø Þ (4) The second component of the total power factor is called distortion power factor and results from A 230/2300 V transformer takes no load current of 6. 38. Induced emf in the primary and the secondary winding lags the flux ϕ by 90 degrees. In conclusion, the power factor of the magnetizing component of a transformer is zero because the voltage and current in the primary winding are 90 degrees out of phase. This is helpful for users who are preparing for their exams, interviews, or professionals who would like to brush up on the fundamentals of Electric Power. The most suitable location for the power factor improvement device is a. The maximum power factors exists in a purely resistive circuit. 919A, 184W Jan 8, 2022 · Power factor of-magnetizing component of a transformer is A. (b) increase the mechanical strength of the assembled core. May 24, 2024 · ∴ Power factor of an AC circuit is defined as the ratio of W / VA. field winding by drawing magnetizing component of the current from dc supply Answer: A Clarification: Excess flux is neutralized y the demagnetizing component. Always leading Ans. 8 lagging. There are two or more windings in a transformer's magnetic core. The magnetizing current (c) Stator power factor is improved. ) that are already sized to accommodate full load operation in the first place. If the power factor is close to unity, for the same KVA rating of the transformer more load can be connected. During periods of low load, the supply voltage is increased, which increases the magnetizing current and causes a decrease in power factor. 37 Ω 600 Ω; The transformer is supplying a load of 10 A at a power factor of 0. e. Answer to Solved Q3. This level depends on the tariff, but often corresponds to a tan ϕ value of 0. Increased magnetizing current. The efficiency of the power transformer is always greater Mar 21, 2018 · Energising a power transformer may cause inrush current, which misleads the protection systems. its magnetizing and loss components of the exciting current are 1 A and 0. Answer: B. 30• Ans. At constant voltage how is frequency affected by flux? a) decreases with an increase in flux b) increases with a decrease in flux c) remains constant d) depends on the This set of Transformers Multiple Choice Questions & Answers (MCQs) focuses on “SC Test on Transformer”. 2. The characteristics of a single-phase transformer include a step-down transformer, low voltage type applications, and rectifying. A transformer comprises of two or more wire coils that are wrapped around common ferromagnetic core. Power factor correction substations__ A. The magnitude of the secondary current is dependent on the turn ratio of the The energy stored in the magnetic field of the transformer is constantly being exchanged between the primary and secondary windings, but no net power is being transferred. The equivalent circuit for a 200/400-V step-up transformer has the following to the low-voltage side: Equivalent resistance 0. 𝟐𝟐 ∗ (20) Using the transformer voltage and current The power factor of the two transformers will be different from the power factor of common load 194. P = power applied (W, watts) U = voltage (V) I = current (A, amps) - or alternatively: 18. The ideal case assumes no losses. ϕ S is the sending end power factor angle. pptx 14 Example 8-2: 300 kVA 2400-120, 60 Hz single phase transformer operates at 2300 volts on the primary side. I 0 sin Φ 0 c. Conclusion: The correct statement for a step down single-phase transformer is: May 9, 2021 · This Website provides Power System Theory, Transformer Theory , Electrical Mcahine Theory, Electrical generation Theory and Electrical MCQs For Exams. 8 lagging power factor Find the estimated current taken by the primary side if a single-phase transformer with a voltage ratio of 440/110 V takes a no-load current of 5 A at 0. Input volt ampere > output volt ampere: - This is generally true for real transformers due to losses, but it is not the ideal case. Additional Information Effect of Secondary Burden Power Factor in PT: Sep 2, 2021 · Magnetizing component of current (current which produces Flux in the transformer) (wattless current). Frequency B. I 0 cot Φ 0 d. Dec 10, 2021 · 2 A low voltage electrical system employs a 300V to 75 step down transformer for safety. Determine the magnetizing current, I_Phi 1 Determine the secondary equivalent current, I_2. Stator Loss Component of Current: Stator Loss Component of Current provides the Stator Iron as well as Copper Loss just like in a Transformer. Then shape of the emf induced in Y-connected 3-phase transformer is non sinusoidal in nature due to _____ a) 3rd harmonic component of currents is absent b) 3rd harmonic component of currents is present c) negative sequence component of current is present The iron core of transformers and other electromagnetic devices is laminated so that at 50 Hz or 60 Hz (or, in general, at power frequency) skin effect is Index Terms—Harmonic content, no-load current, power factor, saturation, transformer I. This is because utilities often charge higher rates a) transformers will be overheated b) power factors of both the transformers will be same c) parallel operation will be not possible d) parallel operation will still be possible, but the power factors at which the two transformers operate will be different from the power factor of the common load View Answer Question: A 3300/300Vsingle phase transformer gives 0. Magnetizing current of the transformer May 31, 2015 · No Load Power Factor, cos ϕ 0 = (I w / I 0) ≈ 0. 𝑰𝑰. All Transformer Questions & Answers given below include a hint and wherever possible link to the relevant topic. ) of 0. The Test: Transformer of Electrical Machines MCQs are made for Electrical Engineering (EE) 2024 Exam. An ideal transformer is having 150 turns primary and 750 turns secondary. Voltage regulation B. V S is the sending end voltage. The fundamental component i exc1 is shown in Fig. A power system network is connected as shown in the figure. 60° D. This set of Electrical Machines Multiple Choice Questions & Answers (MCQs) focuses on “Power Factor Correction by Synchronous Motors”. The lagging reactive power is responsible for the low power factor. Variable frequencies D. 𝟏𝟏 ∗ (19) And, the complex power delivered out of the secondary side is 𝑺𝑺. 6 A respectively and secondary winding burden is purely resistive, its transformation ratio at rated current is : Nov 25, 2019 · The function of the magnetizing component is to produce the magnetizing flux, and thus, it will be in phase with the flux. Why neutral is provided in secondary distribution? A. 37. So the first thing we have to find out is the magnetizing component of the no -road current. Feb 10, 2023 · This article lists 100 Electric Power MCQs for engineering students. Sep 2, 2021 · Answer: A. For a consumer the most economical power factor is usually. Power System Multiple Choice Questions on Symmetrical Components. RMS value / Mean value b. Difference between Power Transformers and Distribution Transformers; Equivalent Circuit of Transformer. primary of a Current transformer when the secondary is connected to the rated load. 8 leading power factor (b) 0. 6A and 60 W as ammeter and wattmeter reading when supply is given to the low voltage winding and high voltage winding is kept open , find: 1 power factor of no-load current 2 magnetizing component 3 iron loss components May 21, 2024 · Transformers Question 1: Which of the following is reduced by laminating the core of a transformer? Copper loss. The V-curves of synchronous motor is plotted between _____ A. The magnetizing component is given by a. 5-6. From the power triangle it is clear that the smaller the reactive power component, the higher is the power factor of the circuit and vice-versa. Sep 17, 2020 · Maximum value of Power Factor is. Then the no load branch resistance and no load branch reactance is a. Find Power factor on no-load, magnetizing component of current and iron loss component of current. The fundamental, 3rd, and 5th harmonic components of the current in a reactor are shown in Fig. (d) Torque developed by the motor increases till it equals the applied torque. The magnetizing component is given by The magnetizing component is given by - Published on 29 Oct 15 See full list on electricalengineeringmcq. It shows a phasor diagram for the case of a resistive load (unity power factor) on the transformer Since the current I 2 is in phase with the secondary voltage V o (FL), the voltage drop across R e2 is also in phase with V o (FL). To determine the efficiency of a transformer, Open Circuit Test and Short Circuit Test are used to calculate rated core and winding losses. The primary coil is connected to a 240 V, 50 Hz source. So no-load current of a transformer has a small magnitude and low power factor. Download these Free Transformer Tests MCQ Quiz Pdf and prepare for your upcoming exams Like Banking, SSC, Railway, UPSC, State PSC. Star-star power transformer is protected by current transformer having. Mar 27, 2022 · In such conditions, specially constructed accurate ratio transformers are used. Hence, the Power factor of a transformer on no load is poor due to the magnetizing reactance of the transformer. The power factor of capacitive circuits is: Leading; Lagging; Both of Jun 22, 2022 · In the case of MV metering, it is sufficient to raise the power factor to a point where the transformer plus load reactive-power consumption is below the level at which a billing charge is made. This set of Transformers Multiple Choice Questions & Answers focuses on “Generator and Power Station Transformers”. 5A power factor (P. Over sizing of supply components that is typical for low power factor systems is not required because the VFD input current is also low. Jul 11, 2024 · In power systems, the term ‘bus’ refers to: A. 31 (cos φ of 0. This article lists 100 Power Systems MCQs for engineering students. Aug 13, 2024 · So LPF (Low Power Factor) Wattmeter is used in open circuit test of transformer. RMS value / Peak value d. So, the power transformer can operate on full load. 2 when connected to a 460-V, 50-Hz supply. If Vs Ia with constant shaft load C. The load power factor ii. The equivalent resistance of electrical system is 15 ohms. The core loss of the transformer; The no-load current; Equivalent resistance referred to the metering side Jun 7, 2023 · All the Instrument Transformer Questions & Answers below include a hint and a link to the relevant topic wherever possible. The total power factor is sometime called the true power factor. 30. PF = power factor . Jun 2, 2015 · a single phase transformer on no- load takes 4 5A at a power factor of 0 25 lagging when connected to a 230v 50Hz supply the number of turns of the primary winding is 250 calculate (i) the magnetizing component Im (ii) iron loss (iii) the maximum value of Apr 6, 2023 · Find the estimated current taken by the primary side if a single-phase transformer with a voltage ratio of 440/110 V takes a no-load current of 5 A at 0. Active component of current and iv. A type of transformer Answer: B The power factor of an AC… Power factor improvement aims at optimal utilization of electrical power, reduction of electricity bills, and reduction of power loss. Power factor. (Better the power factor lesser will be the current flow). If the supply frequency of a transformer is increased, keeping the supply voltage constant, then Both magnetizing component and core loss component of current will decrease. Magnetizing reactance of the transformer Explanation: When the transformer is operating at no load, the secondary winding is open-circuited, which means there is no load on the secondary side of the transformer and, therefore, the current in the secondary will be zero. T “Current Transformer” is a type of instrument transformer designed to step down the current in the secondary for protection and measurement of proportional primary current. 45• B. Which of the following statement is not necessarily valid for ac currents Nov 1, 2021 · The magnetizing inrush current amplitude it was found may reach the level of short-circuit current periodic component at the point of power transformer grid connection. A power system is an environment in which a number of electrical appliances are interconnected to generate, transmit and utilize power. 5 leading; 0. So, both are resistance quantities. Feb 1, 2024 · D. power factor of one of the trans¬formers is leading while that of the other lagging: C. We begin with a comparison of inductor and transformer design for power conversion, analyzing how ripple and therefore magnetizing current is a factor in low-R g transformers. 95 lagging; 0. Explanation: Burden in a current transformer specification refers to the maximum permissible load resistance connected to its secondary winding. for single phase supply B. Question: b) A 3300/300V single phase transformer gives 0. Explanation. 6A | Chegg. The no-load current of a transformer is 15 A at a power factor of 0. The transformer is a vital link in industrial and commercial electric power systems and an essential component in many low-power applications, such as control systems and electronic circuits. A recording of the output of the emf induced for star and delta are recorded. As the load on a transformer increases, the reactance decreases, and the 205. A transformer is efficient device for the reason being. 5A and absorbs 187 W. Undersized Wiring: Undersized wiring (especially in motors Solved MCQs for Transformers, with PDF download and FREE Mock test. The transformer's output power is 0 when the load is not connected across the transformer's secondary. 15 Ω; Core-loss component resistance Equivalent reactance Magnetizing reactance-300 Ω 0. Depending on several factors, the magnitude of the magnetization inrush current can be somewhere from 5 to 30 time the rated full load current of the transformer. 3 on open circuit. The excitation current can be resolved into two rectangular components called the energy and magnetizing components, as shown in the phasor diagram of a non-loaded transformer in Figure 3. 723 lagging. 95 lagging. For a transformer, no load primary current ( I 0) has two components, magnetizing component and active components. Since the load is resistive, the angle between voltage and current is 0°. Assume primary winding turns as 500. Since Iw supplies the iron loss and primary copper loss at no load, it is May 26, 2024 · b) has high magnitude and high power factor c) has small magnitude and high power factor d) has small magnitude and low power factor Answer: d Clarification: Since no-load current lags voltage by the angle of nearly 900, power factor being equal to cosine of the angle between current and voltage, it will be equal to value which is near to 0 Feb 8, 2023 · Correct answer: 1. A voltage level in the network C. 37 2 Core loss component resistance = 600 Magnetizing reactance = 300 When this transformer is supplying a load of 10 A at a power factor of 0. We can neglect the ohmic losses in the winding resistance and reactance because of a very low magnitude of current flows through the LV side of the transformer. 8 lagging (a) Draw the approximate equivalent circuit diagram (b) Determine the magnetizing current This set of Power Systems Multiple Choice Questions & Answers (MCQs) focuses on “Per Unit (PU) System”. 90• C. Explanation: In the Sumpner’s test while the transformers are not supplying any load, full iron-loss occurs in their cores and full copper-loss occurs in their windings; net power input to the transformers being (2P0 + 2Pc). a) magnetically, not electrically b) electrically, not magnetically c) magnetically, also magnetically d) electrically, also electrically 2. From Figure 1. Calculate magnetizing component of no-load current iron loss and maximum value of the flux in the core. Therefore, the inrush current analysis is important in designing and protecting power transformers. Ordinarily this current is small and produces negligible voltage drop in the winding. It supplies 115 kVA to a load that has a power factor of 0. The magnetization current drawn from an AC supply a synchronous motor is used to _____ Jun 4, 2015 · Equivalent Circuit in Single-Phase Transformer - MCQs with Answers Q1. B. Current transformer Solved MCQs for Transformers, with PDF download and FREE mock test. A; Electrical EngineeringI Smart Series MCQs COMPETITIVE EXAMS SET 3(201-300) power-transfer circuits, those with transformers, and addresses transformer design optimization for such circuits. May 26, 2024 · D. Draw the phasor diagram. The low voltage winding of a 400/230 V single phase 50 Hz transformer is to be connected to a 25 Hz supply. I 0 cos Φ 0 b. Core-loss current is often divided into two components: eddy current and hysteresis. Measuring fault currents D. Power factor of the magnetizing component of a transformer is a. Power factor of magnetizing component is unity whereas power factor of loss component is leading Jul 12, 2024 · Which of the following is not a primary component of a power system? A) Transmission line B) Circuit breaker C) Transformer D) Generator Answer: B) Circuit breaker The power generated by a synchronous… Jan 16, 2023 · A single-phase type transformer is built with a core, shell, windings, load, and AC supply. Reactive power - the nonworking power caused by the magnetizing current, required to operate the device (measured in kilovars, kVAR) The power factor for a three-phase electric motor can be expressed as: PF = P / [(3) 1/2 U I] (2) where . As shown in equation (3) the total power factor is the product two components. In using instrument transformers, care should be taken not to open circuit the. In the exact equivalent circuit of a transformer based on ideal transformer, we need to consider the no-load current. Answer: C. Jul 9, 2023 · Since the transformer windings are inductive, the input voltage V P leads the magnetizing current (I mag) by 90°. The core loss is 110 W. 14. Both A and B. 1. Eddy current loss. Only in the case distribution transformer maximum efficiency is achieved at 60% of full load. Magnetizing Current: The load on a power system varies. If the resistance of the primary winding is 0. V o / I m, V o / I c c. exams Under One Roof. The non-linear behaviour of transformer core saturation makes this analysis difficult. 062, find; i. A. NOMENCLATURES B magnetic flux density Br remanence magnetic flux density Bs saturation magnetic flux Jan 30, 2023 · This article lists 100 Transformer MCQs for engineering students. So that from the given options most suitable power factor is 0. If I c is the active component and I m is the magnetizing component of no load current (I o) obtained in the no load test of an induction motor. 25. Since it cannot be eliminated, this creates an Jul 8, 2024 · While in the case of power factor also every device is set to get maximum efficiency at unity power factor. Load Component of Current: The purpose of Load Component of Current is to balance the Rotor mmf which is demagnetizing in nature. Explanation: Power transformers are usually used for transmission purposes as a step-up device. For a load of slightly less than unity power factor leading, the reactive power requirement of the transmission line is supplied by the load only. circuits. 4 because it is the lowest among all of the given power factors. com The transformer exciting current has two components, magnetizing component and core-loss component. The power factor of the two trans-formers will be different from the power factor of common Jun 4, 2015 · A transformer when connected to a 230V, 50Hz supply, under no load draws a current of 4A at a power factor of 0. Jun 4, 2015 · Equivalent Circuit in Single-Phase Transformer - MCQs with Answers Q1. Derivation of the magnetizing current wave from the magnetization curve . A; If the horizontal and vertical components of Earth’s magnetic field are equal then angle of dip ls A. The section contains Power System MCQs on symmetrical component transformation, star delta transformers, sequence impedances of transmission lines, power system network, synchronous machine networks and sequence networks construction. , resistance and reactance) of the windings, and secondary burden power factor. 8. 23, the no-load primary current (I 0) has the following two components: One component of I0, that is I w = I 0 cosθ 0 is in phase with V 1. The core flux (ɸ) is in phase with the magnetizing current (I mag). 8 lagging, calculate (i) Primary current (ii) The secondary terminal voltage. 5 lagging; 0. Jun 24, 2021 · where PF = power factor (percentage) PT = true power (in W) PA = apparent power (in VA) 100 = constant (to convert decimal to percent) In other words, a transformer operating under no-load conditions has a low power factor because the circuit is almost purely reactive. power factor vs Ia The equivalent circuit of a 200/400 V transformer has the following parameters referred to the low voltage side. Explanation: It will be assumed here that the current Io and its magnetizing component Im and its core-loss component Ii are sinusoidal on equivalent rms basis. A 230/110 single phase transformer having an input of 350 VA at no load and rated voltage. All the Electric Power Questions & Answers given below include a hint and a link wherever possible to the relevant topic. Core-Loss Current and Magnetizing Current. Jun 3, 2021 · 18. Circuit and phasor diagram for a transformer on no-load. Which of the following is not changed in transformer substation? A. The investigation is done on 1. Jun 5, 2015 · Q5. Power transformers step up or down the applied input power (Voltage). 955). 25 lagging, when connected to 400V, 50 tHz supply. Dec 17, 2021 · Which type of connection is employed for current transformers for the protection of star- delta connected 3-phase transformer? 3. And no load current is nothing but the vector summation of these two currents. F. 3. Oct 29, 2015 · For a transformer, no load primary current ( I 0) has two components, magnetizing component and active components. all of the above. What is the term for a device that measures the power factor in an electrical circuit? A. The core loss iii. The power factor is given by: PF = cosϕ where ϕ is the angle of displacement between voltage and current. Ideal Transformers - Power The complex power entering the primary side of the transformer is 𝑺𝑺. Near the electrical appliance which is responsible for the poor power factor. f. So, we calculate the core loss and core loss current neglecting the copper loss. zero. Jul 10, 2020 · A transformer is usually employed to transfer energy between circuits of different voltages. C. 15 02 Equivalent leakage reactance = 0. Definite currents B. 2 lagging. Power Factor Meter. Explanation: The transformer is an electrical device that changes AC electric power at one voltage level to ac electric power at another voltage level by the action of magnetic field. primary of a voltage transformer when the secondary is connected to the rated load. The phasor diagram of this case is given. unity b. Voltmeter. What is the power supplied by the transformer to the load? 4200 W; 3840 W; 2100 W; 1920 W Alternator Multiple Choice Questions and Answers. zgkk wkjjucl iwqecl vyojoo bzwzuu ugcf mmjctmbj xocuyovi qdnaz shdce