The primary turns of a 444 V/222 V, 50 Hz single-phase transformer with a core cross-sectional area of 100 cm2, and a maximum flux density of 1.0 T is

(A) 100 (B) 200 (C) 222 (D) 400

1 Answer

Answer :

The primary turns of a 444 V/222 V, 50 Hz single-phase transformer with a core cross-sectional area of 100 cm2, and a maximum flux density of 1.0 T is 200

Related questions

Description : A 220/440 V, 50 Hz, 5 KVA, single phase transformer operates on 220V, 40Hz supply with secondary winding open circuited. Then (A) Both eddy current and hysteresis losses decreases. (B) Both ... same but hysteresis loss increases. (D) Eddy current loss increases but hysteresis loss remains the same.

Last Answer : (A) Both eddy current and hysteresis losses decreases.

Description : The magnetizing reactance of a 4 kV/ 400 V, 50 Hz single-phase transformer on low voltage side is 35 Ω. The magnetizing reactance on the high voltage side is (A) 0.35 Ω (B) 3.5 Ω (C) 350 Ω (D) 3500 Ω

Last Answer : 3500

Description : A single phase transformer is designed to operate from 50 Hz, 1100 V supply and to have an output voltage of 240 V at no load. The core has mean area of 30 cm2 and the flux density has not to exceed 1.3T. The number of secondary turns will be (a) 1270 (b) 1017 (c) 768 (d) 277  

Last Answer : E2=e2=4.44*flux*N2*f=240 V Flux=Flux density* Area Area=30 cm2  =30*10-4 m2 Flux= 1.3*30*10-4  Wb=39*10-4 Wb E=240= 4.44*39*10-4 *N2*50      N2=277.

Description : A single-phase, 230 V, 50 Hz ac mains fed step down transformer (4:1) is supplying power to a half-wave uncontrolled ac-dc converter used for charging a battery (12 V dc) with the series current limiting resistor being 19.04 Ohm. The charging current is  (A) 2.43 A (B) 1.65 A (C) 1.22 A (D) 1.0 A

Last Answer : A single-phase, 230 V, 50 Hz ac mains fed step down transformer (4:1) is supplying power to a half-wave uncontrolled ac-dc converter used for charging a battery (12 V dc) with the series current limiting resistor being 19.04 Ohm. The charging current is 1.0 A

Description : The hysteresis and eddy current losses of a single phase transformer working on 200 V, 50 Hz supply are Ph and Pe respectively. The percentage decrease in these when operated on a 160 V, 40 Hz supply are   (a) 32, 36 (b) 20, 36 (c) 25, 50 (d) 40, 80 

Last Answer : The hysteresis and eddy current losses of a single phase transformer working on 200 V, 50 Hz supply are Ph and Pe respectively. The percentage decrease in these when operated on a 160 V, 40 Hz supply are 20, 36

Description : If a 220/440 V, 50 Hz, 5 KVA, single-phase transformer operates on 220V, 40Hz supply with secondary winding open circuited: (A) both the eddy current and the hysteresis losses will decrease ... losses will increase (D) eddy current losses will increase but the hysteresis losses will remain the same

Last Answer : If a 220/440 V, 50 Hz, 5 KVA, single-phase transformer operates on 220V, 40Hz supply with secondary winding open circuited: both the eddy current and the hysteresis losses will decrease

Description : The primary winding of a 220/6 V, 50 Hz transformer is energised from 110 V, 60 Hz supply. The secondary output voltage will be; (A) 3.6 (B) 2.5 V (C) 3.0 V (D) 6.0 V

Last Answer : The primary winding of a 220/6 V, 50 Hz transformer is energised from 110 V, 60 Hz supply. The secondary output voltage will be: 3.0 V

Description : The flow energy of 5 ft3 of a fluid passing a boundary to a system is 80,000 ft-lb. Determine the pressure at this point.  a. 222 psi  b. 333 psi  c. 444 psi  d. 111 psi formula: Ef= pV

Last Answer : 111 psi

Description : The primary winding of a 220/6 V, 50 Hz transformer is energised from 110 V, 60 Hz supply. The secondary output voltage will be (A) 3.6 V. (B) 2.5 V. (C) 3.0 V. (D) 6.0 V.

Last Answer : (C) 3.0 V.

Description : The primary winding of a 220/6 V, 50 Hz transformer is energised from 110 V, 60 Hz supply. The secondary output voltage will be (A) 3.6 V. (B) 2.5 V. (C) 3.0 V. (D) 6.0 V.

Last Answer : The primary winding of a 220/6 V, 50 Hz transformer is energised from 110 V, 60 Hz supply. The secondary output voltage will be 3.0 V.

Description : The low voltage winding of a 400/230 V, 1-phase, 50 Hz transformer is to be connected to a 25 Hz, the supply voltage should be

Last Answer : The low voltage winding of a 400/230 V, 1-phase, 50 Hz transformer is to be connected to a 25 Hz, the supply voltage should be 115 V.

Description : A 230 V/460 V single-phase transformer operating at 20 A and unity power factor has primary referred resistance of 0.2 Ω and reactance of 0.5 Ω. The approximate primary induced emf is (A) 216 V (B) 226 V (C) 234 V (D) 236 V

Last Answer : A 230 V/460 V single-phase transformer operating at 20 A and unity power factor has primary referred resistance of 0.2 Ω and reactance of 0.5 Ω. The approximate primary induced emf is 226 V

Description : A 230 V, 50 Hz phase controlled single-phase full-controlled SCR bridge converter draws 15 A constant dc current. If the source inductance is 3 mH, the drop in dc output voltage is (A) 4.5 V (B) 6.75 V (C) 9 V (D) 13.5 V

Last Answer : A 230 V, 50 Hz phase controlled single-phase full-controlled SCR bridge converter draws 15 A constant dc current. If the source inductance is 3 mH, the drop in dc output voltage is 9 V

Description : In a 230 V, 50 Hz single-phase SCR bridge converter operating at a firing delay angle, α and with large R-L load, the input source current is (A) sinusoidal current (B) constant dc current (C) continuous rectangular pulses (D) alternating rectangular pulses

Last Answer : In a 230 V, 50 Hz single-phase SCR bridge converter operating at a firing delay angle, α and with large R-L load, the input source current is alternating rectangular pulses

Description : A d.c. voltage of 230 V is imposed on an unloaded 230 V, 50 Hz transformer, it will (A) give high secondary voltage (B) burn out (C) give secondary voltage as per k (D) None of these

Last Answer : A d.c. voltage of 230 V is imposed on an unloaded 230 V, 50 Hz transformer, it will burn out

Description : E.M.F for a coil depends upon A. the cross sectional area B. no. of turns of wire C. the magnitude of magnetic flux density D. all of above

Last Answer : all of above

Description : A single phase transformer rated at 3000 kVA, 69 kV 4.16 kV, 60 Hz has a total internal impedance Zp of 127 ohm, referred to the primary side. Calculate the primary current if the secondary is accidentally short circuited.  (A) 43.5 A (B) 543 A (C) 9006 A (D) 721 A 

Last Answer : 543A

Description : A certain transformer has 200 turns in the primary winding, 50 turns in the secondary winding and 120 volts applied to the primary. What is the voltage across the secondary?  (A) 30 Volts (B) 480 Volts (C) 120 Volts (D) 60 Volts

Last Answer : A certain transformer has 200 turns in the primary winding, 50 turns in the secondary winding and 120 volts applied to the primary. What is the voltage across the secondary?  (A) 30 Volts (B) 480 Volts (C) 120 Volts (D) 60 Volts

Description : The area of the core of a column of cross sectional area A, is  (A) (1/3) A (B) (1/6) A (C) (1/12) A (D) (1/18) A

Last Answer : (D) (1/18) A

Description : A 12 -pole, 440 V, 50 Hz, 3 -phase synchronous motor takes a line current of 100 A at 0.8 pf leading. Neglecting losses, the torque developed will be

Last Answer : A 12 -pole, 440 V, 50 Hz, 3 -phase synchronous motor takes a line current of 100 A at 0.8 pf leading. Neglecting losses, the torque developed will be 1165 Nm

Description : What is the slip (as a percentage) when a 6 pole single phase induction motor operating on 220 V and 60 Hz is rotating at speed of 1140 rpm? A) 60% B) 5% C) 10% D) None of these

Last Answer : What is the slip (as a percentage) when a 6 pole single phase induction motor operating on 220 V and 60 Hz is rotating at speed of 1140 rpm? A) 60% B) 5% C) 10% D) None of these

Last Answer : In the transformer low voltage winding has got more cross-sectional area.

Last Answer : High voltage winding of the transformer has less cross-sectional area.

Description : When the turns ratio of a transformer is 20 and the primary ac voltage is 12 V, the secondary voltage is? A.12 V B.120 V C.240 V D.2,400 V

Last Answer : When the turns ratio of a transformer is 20 and the primary ac voltage is 12 V, the secondary voltage is? A.12 V B.120 V C.240 V D.2,400 V

Description : A single-phase, 50 kVA, 250 V/500 V two winding transformer has an efficiency of 95% at full load, unity power factor. If it is re-configured as a 500 V/750 V auto-transformer, its efficiency at its new rated load at unity power factor will be  (A) 95.752% (B) 97.851% (C) 98.276% (D) 99.241%

Last Answer : A

Description : The capacity of a classifier in 'tons of solid/hr' is given by (where, A = cross-sectional area in m2 , V = rising velocity of fluid in m/sec, S = percentage of solids in the suspension by volume, ρ = density of solids in kg/m3 ) (A) 3.6 AVS.ρ (B) 3.6 A.V.ρ (C) 3.6 A.S. ρ (D) 3.6 AVS/ρ

Last Answer : (A) 3.6 AVS.ρ

Description : If a transformer has 50 turns in the primary winding and 10 turns in the secondary winding, what is the reflective resistance if the secondary load resistance is 250 ohms? A.250 ohms B.25 ohms C.6,250 ohms D.62,500 ohms

Last Answer : 6,250 ohms

Description : A single-phase transformer has a turns ratio of 1 :2 and is connected to a purely resistive load as shown in the figure. The magnetizing current drawn is 1A, and the secondary current is 1A. Ifcore losses and ... reactances are neglected, the primary current is  A)1.41A B)2A C) 2.24A D)3A

Last Answer : A single-phase transformer has a turns ratio of 1 :2 and is connected to a purely resistive load as shown in the figure. The magnetizing current drawn is 1A, and the secondary current is 1A. Ifcore losses and leakage reactances are neglected, the primary current is 2.24A

Description : A solar cell of 350 V is feeding power to an ac supply of 440 V, 50 Hz through a 3-phase fully controlled bridge converter. A large inductance is connected in the dc circuit to maintain the dc current at 20 A ... thyristor will be reverse biased for a period of  (A) 125o (B) 120o (C) 60o (D) 55o

Last Answer : A solar cell of 350 V is feeding power to an ac supply of 440 V, 50 Hz through a 3-phase fully controlled bridge converter. A large inductance is connected in the dc circuit to maintain the ... the solar cell resistance is 0.5 Ohm ,then each thyristor will be reverse biased for a period of 125o

Description : A 3-phase fully controlled bridge converter with free wheeling diode is fed from 400 V, 50 Hz AC source and is operating at a firing angle of 60o. The load current is assumed constant at 10 A due to high load inductance. The input ... 0.552 (C) IDF IPF = = 0.5; 0.478 (D) IDF IPF = = 0.5; 0.318 

Last Answer : A 3-phase fully controlled bridge converter with free wheeling diode is fed from 400 V, 50 Hz AC source and is operating at a firing angle of 60o. The load current is assumed constant at 10 A due to high ... (IDF) and the input power factor (IPF) of the converter will be IDF IPF = = 0.5; 0.478

Description : A three-phase, 440 V, 50 Hz ac mains fed thyristor bridge is feeding a 440 V dc, 15 kW, 1500 rpm separately excited dc motor with a ripple free continuous current in the dc link under all operating conditions, Neglecting the ... at half the rated speed is  (A) 0.354 (B) 0.372 (C) 0.90 (D) 0.955

Last Answer : A three-phase, 440 V, 50 Hz ac mains fed thyristor bridge is feeding a 440 V dc, 15 kW, 1500 rpm separately excited dc motor with a ripple free continuous current in the dc link under all operating conditions, Neglecting the losses, the power factor of the ac mains at half the rated speed is 0.354

Description : A 400 V, 50 Hz 30 hp, three-phase induction motor is drawing 50 A current at 0.8 power factor lagging. The stator and rotor copper losses are 1.5 kW and 900 W respectively. The friction and windage losses are 1050 W and the ... the motor will be (A) 23.06 kW (B) 24.11 kW (C) 25.01 kW (D) 26.21 kW

Last Answer : A 400 V, 50 Hz 30 hp, three-phase induction motor is drawing 50 A current at 0.8 power factor lagging. The stator and rotor copper losses are 1.5 kW and 900 W respectively. The friction and windage losses are 1050 W and the core losses are 1200 W. The air-gap power of the motor will be 25.01 kW

Description : The locked rotor current in a 3-phase, star connected 15 , kW 4 , pole 230 V , 50 Hz induction motor at rated conditions is 50 A. Neglecting losses and magnetizing current, the approximate locked rotor line current drawn when the motor ... Hz supply is  (A) 58.5 A (B) 45.0 A (C) 42.7 A (D) 55.6 A

Last Answer : The locked rotor current in a 3-phase, star connected 15 , kW 4 , pole 230 V , 50 Hz induction motor at rated conditions is 50 A. Neglecting losses and magnetizing current, the approximate locked rotor line current drawn when the motor is connected to a 236 , V 57 Hz supply is 45.0 A 

Description : A 400 V, 50 Hz three-phase induction motor rotates at 1440 rpm on full -load. The motor is wound for

Last Answer : A 400 V, 50 Hz three-phase induction motor rotates at 1440 rpm on full -load. The motor is wound for 4 poles

Description : If a force of 50 N is applied across the cross-sectional area of 5 × 10- 7m2 then stress applied on it is A. 1 × 108 Pa B. 20 Pa C. 50 Pa D. 100 Pa

Last Answer : . 1 × 108 P

Description : Pick out the wrong statement. (A) 'Solvates' are chemical compounds formed by solute with their solvents. When water is the solvent, then it is called a 'hydrate' (B) In heat exchanger ... vertical evaporators, area of central downtake is about 50 to 100% of the total tube cross-sectional area

Last Answer : (C) Heat transfer co-efficient during nucleate boiling is not influenced by the agitation imparted

Description : Cross sectional area of catch water drain should not be more than a) 0 .75 square meter* b) 0. 90 square meter c) 0. 80 square meter d). 50 square meter

Last Answer : a) 0 .75 square meter*

Description :  If a secondary coil has 40 turns, and, a primary coil with 20 turns is charged with 50 V of potential difference, then the potential difference in the secondary coil would be A. 50 V in secondary coil B. 25 V in secondary coil C. 60 V in secondary coil D. 100 V in secondary coil

Last Answer : 100 V in secondary coil

Description : if the rated voltage from the power lines is applied to the primary of a single-phase transformer which is operated on no-load, then

Last Answer : if the rated voltage from the power lines is applied to the primary of a single-phase transformer which is operated on no-load, then input voltage is sinusoidal and input current is non sinusoidal.

Description : Why we are using only 50 Hz for single and three phase electrical instruments?

Last Answer : Synchronization condition: There are five conditions that must be met before the synchronization process takes place. The alternator must have equal line voltage, frequency, phase sequence, phase angle and waveform to that ... in the US and North America and 50 Hz in most of the rest of the world.

Description : What would happen if a power transformer designed for operation on 50 Hz (frequency) were connected to a 500 Hz (frequency) source of the same voltage:  (A) Eddy Current and Hysteresis losses will be ... Current will be too much high  (C) Transformer may start to smoke and burn  (D) No effect

Last Answer : What would happen if a power transformer designed for operation on 50 Hz (frequency) were connected to a 500 Hz (frequency) source of the same voltage:  (A) Eddy Current and Hysteresis losses will be ... will be too much high  (C) Transformer may start to smoke and burn  (D) No effect

Description : A transformer at 25 Hz develops 20 W hysteresis loss and 50 W eddy current loss. If the applied voltage and frequency are doubled, the new core losses are (A) 140 W (B) 180 W (C) 240 W (D) 480 W

Last Answer : A transformer at 25 Hz develops 20 W hysteresis loss and 50 W eddy current loss. If the applied voltage and frequency are doubled, the new core losses are 240 W

Description : For a 100% efficient transformer, the primary winding has 1000 turns and the secondary 100 turns. If the power input to the above transformer is 1000 watts, the power output is_________.

Last Answer : For a 100% efficient transformer, the primary winding has 1000 turns and the secondary 100 turns. If the power input to the above transformer is 1000 watts, the power output is 1000 watts.

Description : What happens to the resistance of a wire when its length as well as the cross-sectional area are doubled? A) It doubles B) It becomes 4 times C) It becomes 2π times D) It remains the same

Last Answer : Automatically the resistivity will increase as they are the factors affecting the resistivity 

Description : If the cross-sectional area of a magnetic field increases, but the flux remains the same, the flux density: A. increases B. decreases C. remains the same D. doubles

Last Answer : If the cross-sectional area of a magnetic field increases, but the flux remains the same, the flux density: decreases

Description : With the increase in the cross sectional area of the conductor, the value of resistance:  (1) Increase (2) Remain same (3) Decrease (4) None of these

Last Answer : With the increase in the cross sectional area of the conductor, the value of resistance: Decrease.

Description : Two aluminium conductors have equal length. The cross-sectional area of one conductor is four times that of the other. If the conductor having smaller cross-sectional area has a resistance of 100 ohms the resistance of other conductor will be 

Last Answer : Two aluminium conductors have equal length. The cross-sectional area of one conductor is four times that of the other. If the conductor having smaller cross-sectional area has a resistance of 100 ohms the resistance of other conductor will be 25 ohms.

Description : A cantilever shaft having 50 mm diameter and a length of 300mm has a disc of mass 100 kg at its free end. The Young’s modulus for the shaft material is 200 GN/m^2. Determine the static deflection of shaft in mm. A 0.144 B 0.244 C 0.344 D 0.444

Last Answer : A 0.144

Description : A 200 V, 50 Hz inductive circuit takes a current of 10 A at 30 degree lagging pf, what is the inductive reactance of the circuit?  (A) 17.8 Ω (B) 100 Ω (C) 178 Ω (D) 10 Ω 

Last Answer : D

Description : In a two -channel oscilloscope operating in x -y mode, two in -phase 50 Hz sinusoidal waveforms of equal amplitude are fed to the two channels. What will be the resultant pattern on the screen ? (a) An ellipse (b) A parabola (c) Straight line inclined at 45° with respect to x-axis (d) A circle

Last Answer : In a two -channel oscilloscope operating in x -y mode, two in -phase 50 Hz sinusoidal waveforms of equal amplitude are fed to the two channels. What will be the resultant pattern on the screen ? (a) An ellipse (b) A parabola (c) Straight line inclined at 45° with respect to x-axis (d) A circle