A large transformer operating at no load draws an exciting current Io of 5A, when the primary is connected to a 120 V, 60 Hz source. From a wattmeter test, it is known that iron losses are equal to 180 W. Calculate the reactive power absorbed by the core. 

(A) 600 var (B) 572 var (C) 180 var (D) 360 var 

1 Answer

Answer :

572var

Related questions

Description : A load with an impedance of 440 ohms is connected across the secondary of the transformer illustrated. If the input voltage is 110 VAC and the step-up ratio is 10 to 1, what will be the primary current? EL-0055 A. 2.5 amps B. 25 amps C. 250 amps D. current cannot be determined with information given

Last Answer : Answer: B

Description : A load is connected to the secondary of the transformer illustrated and the current through the load is 10 amps. If the step-up ratio is 10 to 1 and the input voltage is 110 VAC, what will be the current flow through the primary? EL-0055 A. 1 amp B. 10 amps C. 100 amps D. 1000 amps

Last Answer : Answer: C

Description :  An 8 pole lap wound DC shunt generator is supplying 295A to a load. The field current of the generator is 5A. The current per parallel path is: -  a) 300A b) 200A c) 150A d) 37.5A

Last Answer :  An 8 pole lap wound DC shunt generator is supplying 295A to a load. The field current of the generator is 5A. The current per parallel path is: - 37.5A

Description : Which of the following statements is correct concerning the motor performance curves and data table shown in the illustration? EL-0006 A. The motor RPM at full load is 1737 RPM. B. The motor draws 12.62 kw ... If the motor was developing 10 HP its power factor would be 0.92. D. All of the above.

Last Answer : Answer: D

Description : Six resistance are connected as shown in figure. If total current flowing is `0.5A`, then the potrential difference `V_(A)-V_(B)` is

Last Answer : Six resistance are connected as shown in figure. If total current flowing is `0.5A`, then the potrential difference `V_(A) ... V B. 6 V C. 2 V D. 4 V

Description : A nichrome heating element connected to a 200 V supply draws an intial current of 2.2 A which settles down after a few seconds to a steady value of 2.

Last Answer : A nichrome heating element connected to a 200 V supply draws an intial current of 2.2 A which settles down after a ... is `1.7xx10^(-4) "per"^(@)C`.

Description : A final amplifier of a radio transmitter draws 250 mA of plate current when the plate supply voltage is 1400 volts. If the plate circuit efficiency is 80% and the transmitter is connected to an antenna having a feed impedance of 70 ohms, ... at the feed-point? A. 4.0 A B. 2.2 A C. 1.25 A D. 2.0 A

Last Answer : D. 2.0 A

Description : What is meant by "exciting current" in a transformer?

Last Answer : Exciting current is the current that flows in the primary of a transformer with the secondary open (no load attached).

Description : A 3~phase synchronous motor, connected to infinite bus, is operating at no load at normal excitation. The field excitation of the motor is first decreased to zero and then increased in the ... 2) First decrease and then increase, (3) Increases continuously (4) First increase and then decreased

Last Answer : A 3~phase synchronous motor, connected to infinite bus, is operating at no load at normal excitation. The field excitation of the motor is first decreased to zero and then increased in the reverse direction. The armature current of the synchronous motor will: Increases continuously.

Description : A separately excited generator as compared to a self-excited generator (a) is amenable to better voltage con-trol (b) is more stable (c) has exciting current independent of load current (d) has all above features

Last Answer : Ans: d

Description : What is the maximum allowable primary current of a 2 KVA step-down transformer with a four to one turns ratio if connected across a 440 volt line? A. 1.1 amps B. 4.5 amps C. 18.1 amps D. 27.7 amps

Last Answer : Answer: B

Description : A coil =of inductance `L=50muH` and resistance =`0.5Omega` is connected to a battery of emf=5A. A resistance of `10Omega` is connected parallel to the

Last Answer : A coil =of inductance `L=50muH` and resistance =`0.5Omega` is connected to a battery of emf=5A. A resistance ... is (0.02)x in mJ. Find valuie of x.

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 : What will happen if the primary of a transformer is connected to D.C. supply?  (A) Transformer will operate with low efficiency (B) Transformer will operate with high efficiency (C) No effect (D) Transformer may start to smoke and burn 

Last Answer : What will happen if the primary of a transformer is connected to D.C. supply?  (A) Transformer will operate with low efficiency (B) Transformer will operate with high efficiency (C) No effect (D) Transformer may start to smoke and burn 

Description : For a transformer, operating at constant load current, maximum efficiency will occur at?

Last Answer : For a transformer, operating at constant load current, maximum efficiency will occur at unity power factor.

Description : In the illustrated electronic governor, the circuit card connected to the potential and current transformers is for ________. EL-0046 A. increasing the signal strength to the governor to ... from motorization D. conditioning the load through the use of a magnetic amplifier current transformer

Last Answer : Answer: A

Description : Alternative to Drop.io for Sharing of Large Files?

Last Answer : Dropbox

Description : A coil of 500 turns is linked with a flux of 25 mwb, when carries a current of 12.5A. Calculate the value of self-inductance.

Last Answer : Ans: Self-Inductance: L = NΦ /I = 500 × 25 × 10-3 / 12.5 = 1 H

Description : A 10 kVA, 400 V/200 V single phase transformer with 10% impedance draws a steady short-circuit line current of   (a) 250A (b) 50 A (c) 150 A (d) 350 A 

Last Answer : A 10 kVA, 400 V/200 V single phase transformer with 10% impedance draws a steady short-circuit line current of 250A

Description : The armature resistance of a permanent magnet dc motor is 0.8 Ohm. At no load, the motor draws 1.5 A from a supply voltage of 25 V and runs at 1500 rpm. The efficiency of the motor while it is operating on load at 1500 ... .5 A from the same source will be  (A) 48.0% (B) 57.1% (C) 59.2% (D) 88.8%

Last Answer : The armature resistance of a permanent magnet dc motor is 0.8 Ohm. At no load, the motor draws 1.5 A from a supply voltage of 25 V and runs at 1500 rpm. The efficiency of the motor while it is operating on load at 1500 rpm drawing a current of 3.5 A from the same source will be 48.0%

Description : answers for primary mathematics 5A

Last Answer : You forgot to ask a question there :)

Description : A three-phase star -connected load is operating at a power factor angle ϕ  with ϕ being the angle between

Last Answer : A three-phase star -connected load is operating at a power factor angle ϕ  with ϕ being the angle between Phase voltage and phase current

Description : Increasing the load to the secondary windings of a transformer will cause a/an ____________. A. decrease in the primary voltage B. increase in the primary voltage C. decrease in the primary current D. increase in the primary current

Last Answer : Answer: D

Description : During short circuit test iron losses are negligible because A. The current on secondary side is negligible B. The voltage on secondary side does not vary C. The voltage applied on primary side is low D. Full-load current is not supplied to the transformer

Last Answer : C) the voltage applied on primary side is low

Description : During short circuit test iron losses are negligible because A. The current on secondary side is negligible B. The voltage on secondary side does not vary C. The voltage applied on primary side is low D. Full-load current is not supplied to the transformer

Last Answer : C) the voltage applied on primary side is low

Last Answer : A fridge uses 220 watts from 110 V power source. The Fridge then draws a current from the source equal to 2 amps.

Description : A load with an impedance of 440 ohms is connected across the secondary of the device illustrated. If the input voltage is 110 VAC and the step-up ratio is 10 to 1, what will be the primary current? EL-0055 A. 2.5 amps B. 25 amps C. 250 amps D. current cannot be determined with information given

Last Answer : Answer: B

Description : A load is connected to the secondary of the device illustrated and the current through the load is 10 amps. If the step-up ratio is 10 to 1 and the input voltage is 110 VAC, what will be the current flow through the primary? EL-0055 A. 1 amp B. 10 amps C. 100 amps D. 1000 amps

Last Answer : Answer: C

Description : 52 A transformer has 1000 primary turns, connected to 250V ac supply. To get 400V secondary voltage the no of secondary turns should be A. 1600 B. 250 C. 400 D. 1250

Last Answer : A. 1600

Description : ______ signal is generated by combining RD and WR signals with IO/M.   (a) Control (b) System (c) Register (d) Memory

Last Answer : Control signal is generated by combining RD and WR signals with IO/M. 

Description : A 240 V, dc shunt motor draws 15 A while supplying the rated load at a speed of 80 rad/s. The armature resistance is 0.5 W and the field winding resistance is 80 W. The net Voltage across armature resistance at the time of plugging will be

Last Answer : A 240 V, dc shunt motor draws 15 A while supplying the rated load at a speed of 80 rad/s. The armature resistance is 0.5 W and the field winding resistance is 80 W. The net Voltage across armature resistance at the time of plugging will be 474 V

Description : If a transformer is connected to a DC source, the transformer will overload at the ____________. A. contacts B. primary coil C. secondary coil D. core

Last Answer : Answer: B

Description : In a Tap changing transformer on which side is the tap connected, primary side or secondary side?

Last Answer : A. Tapings are always connected to high voltage winding side, because of low current. If we connect tapings to low voltage side, sparks will produce while tap changing operation due to high current.

Description : In a three phase transformer, if the primary side is connected in star and secondary side is connected in delta, what is the angle difference between phase voltage in the two cases. (A) delta side lags by -30°. (B) star side lags by -30°. (C) delta side leads by 30°. (D) star side leads by -30°.

Last Answer : Ans: C This is vector group and has +30° displacement. Therefore, delta side leads by +30°.

Description : The primary coil of a transformer is connected to a 60 V ac source. The secondary coil is connected to a 330 ohms load. The turns ratio is 3:1. What is the secondary voltage? A.2 V B.20 V C.180 V D.18 V

Last Answer : The primary coil of a transformer is connected to a 60 V ac source. The secondary coil is connected to a 330 ohms load. The turns ratio is 3:1. What is the secondary voltage? A.2 V B.20 V C.180 V D.18 V

Description : In a three phase transformer, if the primary side is connected in star and secondary side is connected in delta, the angle difference between phase voltage in the two cases will be: (A) delta side will lag by -30° ... will lag by -30° (C) delta side will lead by 30° (D) star side will lead by -30°

Last Answer : In a three phase transformer, if the primary side is connected in star and secondary side is connected in delta, the angle difference between phase voltage in the two cases will be: delta side will lead by 30° 

Description : A circular coil of `20turns` and radius `10cm` carries a current of `5A`. It is placed in a uniform magnetic field of `0*10T`. Find the torque acting

Last Answer : A circular coil of `20turns` and radius `10cm` carries a current of `5A`. It is placed in a uniform magnetic ... Nm B. 3.14 Nm C. 0.314 Nm D. zero

Description : In the circuit shown the cell is ideal. The codil has an inductance of 2H and will blow when the current through it reaches 5a. The switch is closed a

Last Answer : In the circuit shown the cell is ideal. The codil has an inductance of 2H and will blow when the ... Find the time (in second)n when fuse will blow.

Description : Why earth fault current of generator should not be reduced below 5A? 

Last Answer : To limit over voltage due to neutral shift.  

Description : Calculate the flux density due to a circular conductor of radius 100nm and current 5A in air. a) 10 b) 100 c) 0.1 d) 1

Last Answer : a) 10

Description : Find the Lorentz force due to a conductor of length 2m carrying a current of 1.5A and magnetic flux density of 12 units. a) 24 b) 36 c) 32 d) 45

Last Answer : c) 32

Description : Find the power of an inductor of 5H and current 4.5A after 2 seconds. a) 25.31 b) 50.62 c) 102.4 d) 204.8

Last Answer : a) 25.31

Description : Find the magnetic field intensity due to a solenoid of length 12cm having 30 turns and current of 1.5A. a) 250 b) 325 c) 175 d) 375

Last Answer : d) 375

Description : Find the magnetic field intensity due to an infinite sheet of current 5A and charge density of 12j units in the positive y direction and the z component is below the sheet. a) 6 b) 0 c) -6 d) 60k

Last Answer : c) -6

Description : Find the magnetic field intensity due to an infinite sheet of current 5A and charge density of 12j units in the positive y direction and the z component is above the sheet. a) -6 b) 12k c) 60 d) 6

Last Answer : d) 6

Description : Find the force due to a current element of length 2cm and flux density of 12 tesla. The current through the element will be 5A. a) 1 N b) 1.2 N c) 1.4 N d) 1.6 N

Last Answer : b) 1.2 N

Description : Find the magnetic flux density when a point from a finite current length element of current 0.5A and radius 100nm. a) 0 b) 0.5 c) 1 d) 2

Last Answer : c) 1

Description : Find the force on a conductor of length 12m and magnetic flux density 20 units when a current of 0.5A is flowing through it. a) 60 b) 120 c) 180 d) 200

Last Answer : b) 120

Description : The current in the circuit shown in figure - What will be the current in the circuit? a. 1/45A b. 1/10A c. 1/5A d. 5A

Last Answer : b. 1/10A