MCQs: In a transformer the resistance between its primary and secondary is_____? - Electrical Engineering Questions - Transformers Mcq In a transformer, the primary and secondary windings are not electrically connected therefore the resistance between them is ideally infinite but an autotransformer does the same using a single coil as primary with one or more tap for secondary in different parts of the coil. In this case, the resistance will ideally be zero or a short circuit In a transformer the resistance between its primary and secondary is. A. zero. B. 1 ohm. C. 1000 ohms. D. infinite. Answer: Option Transformers In a transformer the resistance between its primary and secondary is In a transformer the resistance between its primary and secondary is: A. zero: B. 1 ohm: C. 1000 ohms: D. infinit
In a transformer the resistance between its primary and secondary should be. A. zero.. In a transformer the resistance between its primary and secondary should be infinity Transformers. In a transformer the resistance between its primary and secondary is_____? In a transformer the resistance between its primary and secondary is_____? A. zero B. 1 ohm C. 1000 ohms D. infinite. Mcq Added by: admin. Transformers Transformers. IF YOU THINK THAT ABOVE POSTED MCQ IS WRONG
A good voltage regulation of a transformer means. A. output voltage fluctuation from no load to full load is least. 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 Hence resistance found in a transformer between prim. and secondary is due to imperfections. To check for the extent of parasetic R (Z), there are high voltage test (s) at a magnitude much higher than working voltage. Low level of isolation is harmful to sensitive loads connected to the secondary In a transformer the resistance between its primary and secondary is_____? A. zero. B. 1 ohm. C. 1000 ohms. D. infinit In a transformer the resistance between its primary and secondary is Single In a transformer the resistance between its primary School Technological University of the Philippines Manil
52. In a transformer the resistance between its primary and secondary is (a) zero (b) 1 ohm (c) 1000 ohms (d) infinite Answer: d. 53. A transformer oil must be free from (a) sludge (b) odour (c) gases (d) moisture Answer: d. 54. A Buchholz relay can be installed on (a) auto-transformers (b) air-cooled transformers (c) welding transformers (d) oil cooled transformers The ideal transformer has no resistance, but in the actual transformer, there is always some resistance to the primary and secondary windings. For making the calculation easy the resistance of the transformer can be transferred to the either side Click here for the answer of In a transformer the resistance between its primary and secondary is_____? by thebuzzfeed with answers and explanation. Prepare Practic
In transformer there is no physical connection between primary and secondary therefore the resistance you are talking about is actually reluctance. Reluctance purely depends on the permiability of core material used in construction and the configuration of core In a transformer the coils are not electricaly connected therefore the resistance is ideally infinite. But an autotransformer does the same using a single coil as primary with one or more taps for secondary in different parts of the coil. In this case the resistance will ideally be ZERO, or a short-circuit if you will #short
111. The secondary of a current transformer is always short-circuited under operating conditions because it (a) avoids core saturation and high voltage induction (b) is safe to human beings (c) protects the primary circuit (d) none of the above Ans: a. 112. In a transformer the resistance between its primary and secondary should be (a) zero (b. Transformers. In a transformer the resistance between its primary and secondary should be_____? In a transformer the resistance between its primary and secondary should be_____? A. zero B. 10 Q C. 1000 Q D. infinity. Mcq Added by: admin. Transformers. In a transformer, the coils are not electrically connected therefore the resistance is ideally infinite. BUT an auto transformer does the same using a single coil as primary with one or more taps for secondary in different parts of the coil. In this case, the resistance will ideally be ZERO, or a short-circuit if you will. 18 In a transformer the magnetic coupling between the primary and secondary winding can be increased by increasing the number of turns. using soft material for winding. using the magnetic core of low reluctance. using transformer oil of better quality. Answerc; The short circuit test on a transformer is conducted to obtain hysteresis loss. eddy.
Step down Transformer: These transformers are used to convert high voltage primary supply to low voltage secondary output. Based on the Medium of Core Used. In a transformer, we will find different types of cores that are used. Air core Transformer: The flux linkage between primary and secondary winding is through the air. The coil or windings. Transformer Basics Example No1. A voltage transformer has 1500 turns of wire on its primary coil and 500 turns of wire for its secondary coil. What will be the turns ratio (TR) of the transformer. This ratio of 3:1 (3-to-1) simply means that there are three primary windings for every one secondary winding Learn Transformers MCQ questions & answers are available for a Electrical Engineering students to clear GATE exams, various technical interview, competitive examination, and another entrance exam. Transformers MCQ question is the important chapter for a Electrical Engineering and GATE students. Page-5 section- Clarification: The primary and secondary windings have zero resistance. It means that there is no ohmic power loss and no resistive voltage drop in the ideal transformer. An actual transformer has finite but small winding resistances. 3. In a transformer the resistance between its primary and secondary is _____ a) Zero b) Very smal 196. Preferably, the resistance between the primary and the secondary of a transformer should be. A. as low as possible. B. as high as possible. C. low or high depending upon whether it is step up or step down respectively. D. high or low depending upon whether it is step up or step down respectivel
These losses occur due to ohmic resistance of the transformer windings. If I 1 and I 2 are the primary and the secondary current. R 1 and R 2 are the resistance of primary and secondary winding then the copper losses occurring in the primary and secondary winding will be I 1 2 R 1 and I 2 2 R 2 respectively. Therefore, the total copper losses. 1. In transformer the resistance between primary and secondary coil is Ideally infi . View the full answer. Transcribed image text: *In a transformer the resistance between its primary and secondary is infinity 1 ohm zero o 1000 ohm The value of flux involved the e.m.f. equation of a transformer is instantaneous value o r.m.s.value average. Transformer Resistance Test. If an infinite resistance is obtained in either of the two tests this will indicate an open circuit in that winding and hence non-function of the transformer. The resistance values of both windings may differ quite substantially due to the difference in the number of turns on each winding and also the difference in. 7. The primary and secondary induced emf E 1 & E 2 in a 2 winding transformer are always a. equal in magnitude b. antiphase with each other c. Inphase in each other d. determine by load on transformer secondary 8. A step up transformer increases a. voltage b. current c. power d. frequency 9 Buy your electronic components, modules, sensors at the best price:visit: https://www.dpvtechnology.comhow to find primary and secondary winding of transform..
Transformer Current Calculator: Just enter the number of phases, transformer rating in VA/kVA/MVA, the voltage of the primary winding or the primary current, then press the calculate button to get the secondary and primary current. Also, you can find the type of transformer either step down or step. Reset Button to uses to clear the [ Transformer Phase shift: In a Power or distribution transformer, there is usually a phase difference between the primary and secondary currents of a 3-phase power transformer.. This exact angle of phase shift is mentioned in the transformer's nameplate details.Even, if you use proper turn-ratio, a differential current may flow through the relay under normal conditions and cause relay operation A 50kVA transformer has 200 turns and 40 turns on the primary and secondary windings respectively. Resistance on primary and secondary are 0.15 Ω and 0.005 Ω respectively. The value of leakage reactances on primary and secondary windings are 0.55 and 0.0175 Ω respectively. If the supply voltage on the primary side is 1100V, Calculate THREE-PHASE TRANSFORMER (Examples) Example 1 A 500-kVA, 3-phase, 50 Hz transformer has a voltage ratio (line voltages) of 33/11 kV and is delta/star connected. The resistances per phase are: high voltage 35 Ω, low voltage 0.876 Ω and the iron loss is 3050 W. Calculate the value of efficiency at full-load and one-half of full-load respectively.
- Secondary windings, connected to the load; - Iron core, which link the flux in both windings; The primary and secondary voltages are denoted by 1 and 2 respectively. The current entering the primary terminals is 1. Step-up transformer If the primary coil has 3 loops and the secondary coil has 30, the voltage is stepped up 10 times A transformer is an electric induction device, and it only works with alternating current. It consists of a primary and secondary coil. Each coil may be wrapped around its own metallic core, or the coils may both be wrapped around the same core
A step-up transformer works on 220V and gives 2 A to an external resistor. The ratio of the number of turns between the primary and secondary coils is 2:25. Assuming 100% efficiency, find the secondary voltage, primary current and power delivered Example 3: A single phase transformer has 350 primary and 1,050 secondary turns. The net cross-sectional area of the core is 55 cm 2. If the primary winding be connected to a 400 V, 50 Hz single phase supply, calculate (i) maximum value of the flux density in the core and (ii) the voltage induced in the secondary winding
The material of primary and secondary coils must be stable so that their electrical resistance is extremely little. Flux Coupling Both the coils of the transformer must be wound in such a manner that flux coupling among the coils is utmost as power transfer from one coil to another will takes place during flux linkages The two windings of this transformer have small resistance. Because of the resistance, eddy current and hysteresis there are no losses in the transformer. The efficiency of this transformer is 100%; The total flux generated in the transformer has restricted the core & connects with the windings. Therefore, its flux & inductance leakage is zero A practical power transformer differs from the ideal in that its core is not infinitely permeable and demands an excitation N 1 I 0 = N 1 I 1 − N 2 I 2; the primary and secondary coils have both resistance and magnetic leakage; and core losses occur.By treating these effects separately, a practical transformer may be considered as an ideal transformer connected into an external network to. A three-phase isolation transformer is a 3-phase transformer, they have isolated primary and secondary windings. So the power input will be isolated from the power output. 3-phase isolation transformer has 3 primary and secondary windings that are separated from each other and these windings are insulated from each other The 300 turn primary of a transformer has resistance 0.82 Ω and the resistance of its secondary of 1200 turns is 6.2 Ω. Find the voltage across the primary if the power output from the secondary at 1600V is 32 kW. Calculate the power losses in both coils when the transformer efficiency is 80%
Transformers MCQ questions Which of the following does not change in a transformer?(a) Current(b) Voltage(c) Frequency(d) All of the aboveAns: c In a transformer, the energy is conveyed from primary to secondary(a) through cooling coil(b) through air(c) by the flux(d) none of the aboveAns: c A transformer core is laminated to(a) reduce. The average temperature of insulating oil should be taken 3 to 8 hours after de-energizing transformer and when the difference between top and bottom oil temperatures becomes less than 5 o C.. The resistance can be measured by a simple voltmeter ammeter method, Kelvin Bridge meter or automatic winding resistance measurement kit (ohm meter, preferably 25 Amps kit)
Ns = number of turns on the secondary coil Np = number of turns on the primary coil Vs = voltage across the secondary coil Vp = voltage across the primary coil So if number of turns on the primary coil is more than on the secondary coil, the output voltage will be lesser than the input voltage. This is called a step down transformer. In this. The voltages of the phase of primary and secondary windings in each transformer can be recorded and comparisons made to get the phase relation between them. Oil Tests The oil that provides insulation and cooling properties for a transformer should be tested before the transformer is energized, and periodically as a part of a regular maintenance. Let us consider a particularly simple transformer in which the primary and secondary coils are solenoids sharing the same air-filled core. Suppose that is the length of the core, and is its cross-sectional area. Let be the total number of turns in the primary coil, and let be the total number of turns in the secondary coil. Suppose that an alternating voltag Audio Transformer creates isolation between the output speakers or audio circuitry with the transformer's input side amplifier system. The primary and secondary winding turns ratio fixed to 1:1. Due to this, the transformer does not alter the voltage or current level. It does only create isolation between the Input amplifiers with the output speaker system
If the secondary coil is shorted, the current in this coil is so directed that it opposes a change of the flux. Therefore the variation of the flux is much smaller, and so is the induced voltage. This current is called short circuit current and its magnitude is very high due to zero impedance offered by the load (secondary winding is short-circuited).. Now, if we reduce the applied voltage on the transformer primary i.e. we apply a percentage of rated voltage in transformer primary, current on both windings will also reduce The % of primary voltage that is required to produce the rated secondary current is what is known as %impedance or per-unit impedance. There is another way of defining the %Z or % Impedance or leakage reactance. A transformer is a nothing but two (or more) coils coupled by magnetic field. Ideally all the magnetic field flux from the primary. A transformer works on the principle of mutual induction. So, when there is a change in the current of one coil, an electric current is also induced in the other coil in its proximity. Every transformer consists of two coils or winding: primary and secondary. The primary winding is connected to the AC power source and the secondary to the load
Ideal transformer equations. By Faraday's law of induction: =. . . (eq. 1) =. . . (eq. 2) Where is the instantaneous voltage, is the number of turns in a winding, dΦ/dt is the derivative of the magnetic flux Φ through one turn of the winding over time (t), and subscripts P and S denotes primary and secondary.. Combining the ratio of eq. 1 & eq. 2: Turns ratio = = =. . A 1-phase transformer has a turn ratio of 6. The resistance and reactance of primary winding are 0.9 W and 5 W respecitvely and those of the secondary are 0.03 W and 0.13 W respectively.If 330 -V at 50-Hz be applied to the high voltage winding with the low-voltage winding short- circuited, find the current in the low-voltage winding and its power factor (b) A current transformer with bar primary has 300 turns in its secondary winding. The resistance and reactance of the secondary circuit are 1.5 Ω and 1.0 Ω respectively, including the transformer winding. With 5A flowing in the secondary winding, th 45) A transformer takes a current of0.6 A and absorbs 64 W when the primary is connected to its normal supply of200v, 50Hz, the secondary being on open cir uit. The iron loss component of current is 0.2A 0.43A IA 0.32A 46) A 250 v DC shunt motor takes a total current of 20A
In a transformer it is observed that, all the flux linked with primary winding does not get linked with secondary winding. A small part of the flux completes its path through air rather than through the core (as shown in the fig at right), and this small part of flux is called as leakage flux or magnetic leakage in transformers. This leakage flux does not link with both the windings, and hence. Omar Salah Elsayed Atwa, in Practical Power System and Protective Relays Commissioning, 2019. 10.5 Types of Current Transformers 10.5.1 Wound Primary Type Current Transformer. This CT has conventional windings (primary and secondary) formed of copper wire wound round a core. It is used for auxiliary CTs and for many low or moderate ratio CTs used in switchgear of up to 11 kV rating A current transformer (CT) is a type of transformer that is used to reduce or multiply an alternating current (AC). It produces a current in its secondary which is proportional to the current in its primary. Current transformers, along with voltage or potential transformers, are instrument transformers.Instrument transformers scale the large values of voltage or current to small, standardized. When the input voltage to the transformer primary is kept constant and a load is connected to the secondary terminal, the secondary voltage decreases due to internal impedance. The comparison of no load secondary voltage to the full load secondary voltage is called voltage regulation of the transformer Power transformers are limited in the amount of power they can transfer from primary to secondary winding(s). Large units are typically rated in VA (volt-amps) or kVA (kilo volt-amps). Resistance in transformer windings contributes to inefficiency, as current will dissipate heat, wasting energy
An iron core transformer with a primary voltage of 240 volts has 250 turns in the primary and 50 turns in the secondary. Find the secondary voltage. Solution: Solve for V s. V s = (Ns/Np) Vp. V s = (50/250) 240. V s = 48 volts. Example 3: A power transformer has a turns ratio of 1:4 parameters from the primary to the secondary or the secondary to the primary. These parameters are resistance, reactance, impedance, current and voltage. The impedances in the primary and secondary windings are, The impedance ratio is equal to the square of the turns ratio. The important points for transferring parameters are (i) R In a transformer the resistance between its primary and secondary is _____ a) Zero b) Very small c) Cannot be predicted d) Infinite View Answer. a common core for its primary and secondary windings d) core of stainless steel and winding of pure copper metal View Answer In a transformer, the resistance between its primary and secondary should be..... 1) infinity 2) zero 3) 500 ohm 4) nearly 1
5) If R 1 is the primary winding resistance and R 2 is the secondary winding resistance then the equivalent resistance of the transformer as referred to the primary is a. R 1 + R 2 /K are shown in Fig. 33.5. The ratio of transformation between primary and secondary line voltage is exactly the same as that of each transformer. Further, the secondary voltage triangle abc occupies the same relative position as the primary voltage triangle ABC i.e. there is no angular displacement between the two. More In a transformer, the coefficient of mutual inductance between the primary and the secondary coil is 0.2 henry. When the current changes by 5 ampere/second in the primary, the induced e.m.f. in the secondary will be. [MP PMT 1989
This means that a 3-phase transformer can have its primary and secondary windings connected the same (delta-delta or star-star), or differently (delta-star or star-delta). It's important to remember that the secondary voltage waveforms are in phase with the primary waveforms when the primary and secondary windings are connected the same way Transformers are used for the transmission of electrical energy. At a different voltage level, transformers can change the electrical energy of a given voltage. It consists of two coils named as Primary coil and a Secondary coil which is wound on a soft iron core. The soft iron core is laminated to minimize eddy currents The primary and secondary circuits secondary circuits typically operate different voltages and currents, with the ratio between them determined by the transformer's characteristics. Requirements for transformers are described in NEC Article 450. Transformers are ubiquitous in modern life, with a variety of characteristics, ratings and uses
When constructing a transformer, it becomes very important to specify the type of transformer as either step up or step down as this determines the number of turns that will exist in the primary or secondary coil. Types of Transformers: Majorly there are three types of voltage transformers; 1. Step Down Transformers. 2. Step Up Transformers. 3 Copper loss is due to ohmic resistance of the transformer windings. Copper loss for the primary winding is I 1 2 R 1 and for secondary winding is I 2 2 R 2.Where, I 1 and I 2 are current in primary and secondary winding respectively, R 1 and R 2 are the resistances of primary and secondary winding respectively. It is clear that Cu loss is proportional to square of the current, and current. The primary and secondary coils of a transformer have 50 and 1500 turns respectively. If the magnetic flux ϕ linked with the primary coil is given by ϕ = ϕ 0 + 4t, where ϕ is in webers, t is time in seconds and ϕ 0 is a constant, the output voltage across the secondary coil is (a) 120 volt The greater the value of either resistance or current, the greater is the power dissipated. The primary and secondary windings of a transformer are usually made of low-resistance copper wire. The resistance of a given winding is a function of the diameter of the wire and its length. Copper loss can be minimized by using the proper diameter wire In a step-down transformer, Vs < Vp. Example. A mains (230 volt) transformer has 11,500 turns on its primary coil and 600 turns on its secondary coil. Calculate the voltage obtained from the.
Current transformers play an important role in the monitoring and protection of electrical power systems. CT's are instrument transformers used for converting primary current into a reduced secondary current for use with meters, relays, control equipment and other instruments.. The importance of instrument transformer tests is often underestimated These transformers usually have a greater number of turns in the secondary than in the primary; common step-up ratios being 1 to 2 or 1 to 4. With audio transformers the impedance of the primary and secondary windings is as important as the ratio of turns, since the transformer selected should have its impedance match the circuits to which it. A step-up transformer has a higher secondary voltage than its primary voltage. A step-down transformer has a lower secondary voltage than its primary voltage. As in an ideal transformer, electrical power should be conserved (per the law of conservation of energy), in a step-up transformer secondary current is lower than the primary current and. It occurs in the transformer's winding (primary winding and secondary winding) which consists of copper (Cu) conductor. So, sometimes core loss is also known as 'Winding Loss'. How to reduce copper losses in a transformer? Copper loss is caused by the ohmic resistance (R) of the transformer winding and electric current (I)
The primary and secondary coils of a transformer are the key components in performing its basic function of transforming voltage and current. Materials are used to insulate the primary and secondary coils. In transformers, in addi-tion to the primary and secondary coils, there are several other important com-ponents and accessories The current transformer basically consists of an iron core upon which primary and secondary windings are wound. The primary winding of the transformer is connected in series with the load and carries the actual current flowing to the load, while the secondary winding is connected to a measuring device or a relay Transformer winding resistance is very important factor for the life of any transformer, this test is part of type tests, routine tests and field tests.The purpose of winding resistance test is to determine the following: Calculation of the I 2 R losses in transformer.; Calculation of winding temperature at the end of temperature rise test of transformer