17 views
in DC machine by
A 50 kW dc shunt is loaded to draw rated armature current at any given speed. When driven 

(i) at half the rated speed by armature voltage control and (ii) at 1.5 times the rated speed by field control, the respective output powers delivered by the motor are approximately. (A) 25 kW in (i) and 75 kW in (ii) (B) 25 kW in (i) and 50 kW in (ii) (C) 50 kW in (i) and 75 kW in (ii) (D) 50 kW in (i) and 50 kW in (ii)

1 Answer

+1 vote
by

A 50 kW dc shunt is loaded to draw rated armature current at any given speed. When driven 

(i) at half the rated speed by armature voltage control and (ii) at 1.5 times the rated speed by field control, the respective output powers delivered by the motor are approximately. (A) 25 kW in (i) and 75 kW in (ii) (B) 25 kW in (i) and 50 kW in (ii) (C) 50 kW in (i) and 75 kW in (ii) (D) 50 kW in (i) and 50 kW in (ii)

Related questions

1 answer 15 views

An unsaturated dc shunt motor runs at its rated speed when rated voltage is applied to it. If the supply voltage to the motor is reduced by 25%, the speed of the motor  (a) Increases by 25% (b) Remains the same (c) Decreases by 25% (d) Decrease only slightly by an amount less than 25% 

asked May 13, 2018 in Power Electronics by Shimroz123
1 answer 22 views

A DC shunt motor has rated rpm of 480. Certain industrial application requires this motor to run at 540 rpm for some time. Which speed control will be desirable? A) Ward Leonard control B) Armature current control C) Field resistance control D) It is not possible to run the motor at more than the rated rpm 

asked Jun 17, 2018 in DC machine by Shimroz123
1 answer 80 views

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  (A) 58.5 A (B) 45.0 A (C) 42.7 A (D) 55.6 A

asked May 17, 2018 in Electrical Machine by Shimroz123
0 answers 21 views

A dc shunt generator has a speed of 800 rpm when delivering 20 A to the load at the terminal voltage of 220V. If the same machine is run as a motor it takes a line current of 20A from 220V supply. The speed of the machine (in rpm) will be:  (A) 800 (B) more than 800 (C) less than 800 (D) none of the above

asked Apr 9, 2018 in Electrical Engineering by Shimroz123
1 answer 33 views

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

asked May 8, 2018 in Electrical Machine by Shimroz123
0 answers 17 views

A DC shunt generator supplies 450 A at 230 V. The resistances of shunt field and armature are 50 Ω and 0.025 Ω respectively. What will be the armature voltage drop?  (A) 11.24 V (B) 22.7 V (C) 31.6 V (D) 38.4 V 

asked Apr 5, 2018 in Electrical Engineering by Shimroz123
1 answer 36 views

A 200 V dc shunt motor is running at 1000 rpm and drawing a current of 10 A. Its armature winding resistance is 2 Ohm. It. is braked by plugging. The resistance to be connected in series with armature to restrict armature current to 10 A, is

asked May 3, 2018 in Electrical Machine by Shimroz123
0 answers 44 views

If a four pole synchronous generator driven at 1500 rpm feeds a 6-pole induction motor, which is loaded to run at a slip of 5%, then speed of the motor will be   (a) 1000 rpm (b) 950 rpm (c) 1500 rpm (d) 1450 rpm

asked Apr 10, 2018 in Electrical Engineering by Shimroz123
0 answers 23 views

The constant of a given energy meter is 500 revolution/kWh. At the test 4.4 kW full load, meter completes 50 revolutions in 86 seconds. The percentage error of the meter is (a) –4.86% (b) 4.86% (c) 2.0% (d) 3.0%

asked May 26, 2018 in Electrical Measurements and Instrumentation by Shimroz123
2 answers 88 views

A 220 V shunt motor develops a torque of 54 N-m at armature current of 10 A. The torque produced when the armature current is 20 A, is?

asked Mar 26, 2018 in DC motor by Shimroz123
0 answers 18 views

The method of speed control used for increasing the speed of a dc shunt motor above its rated speed is  1) armature resistance control 2) field control (3) armature voltage control (4) series parallel control 

asked Apr 10, 2018 in Electrical Engineering by Shimroz123
1 answer 148 views

A 50 Hz, 4 pole turboalternator rated at 20 MVA. 13.2 KV has an inertia constant H = 4 KW sec/KVA. The K.E. stored in the rotor at synchronous speed is

asked May 3, 2018 in Electric Power Transmission by Shimroz123
1 answer 19 views

A 1000W heater is rated to operate at a direct current (DC) of 10A. If the heater is supplied alternating current (AC) for producing the same quantity of heat the value of current should be  a. Iav=10A b. Irms=10A c. Ipeak=10A 

asked May 17, 2018 in Electrical Engineering by Shimroz123
1 answer 13 views

The no load speed of a d.c. shunt motor is 1140 rpm. At full load, the armature reaction weakens the main flux by 5% whereas the armature circuit voltage drops by 10%. The motor full load speed in rpm will be: (A) 1080 (B) 1203 (C) 1000 (D) 1200

asked Apr 11, 2018 in Computer Engineering by Shimroz123
0 answers 19 views

A 10 kW electric motor drives a vehicle at an average speed of 50 Km/h. Ten, 12 V, 100A-h batteries supply the motor, the maximum distance that the vehicle may travel before the batteries must be recharged, will be : (A) 30 Km (B) 45 Km (C) 60 Km (D) 80 Km

asked Mar 31, 2018 in Electrical Engineering by Shimroz123
0 answers 21 views

A dc shunt motor runs at 500 r.p.m at 220 V. A resistance of 4.5 Ω is added in series with the armature for speed control. The armature resistance is 0.5 ohms. The current to stall the motor will be (1) 44 A (2) 50 A (3) 44.4 A (4) 60 A  

asked Apr 11, 2018 in Electrical Engineering by Shimroz123
1 answer 8 views

A dc series motor driving and electric train faces a constant power load. It is running at rated speed and rated voltage. If the speed has to be brought down to 0.25 p.u. the supply voltage has to be approximately brought down to  (A) 0.75 p.u (B) 0.5 p.u (C) 0.25 p.u (D) 0.125 p.u

asked May 18, 2018 in DC motor by Shimroz123
0 answers 8 views

A separately excited dc generator is running at rated speed and at no load. If its field winding is suddenly connected to a dc source then rise in armature generated voltage is governed by (1) Armature time constant (2) Field time constant (3) Both (a) and (b) (4) Mechanical time constant

asked Apr 11, 2018 in Electrical Engineering by Shimroz123
1 answer 18 views

Armature shunting method of speed control of dc shunt motor is preferred over annature resistance method due to:  (1) Better speed regulation (2) Less loss in external resistance (3) Simplicity in control circuit (4) Reduced cost of controller

asked Apr 9, 2018 in Electrical Engineering by Shimroz123
1 answer 18 views

A synchronous generator is feeding a zero power factor (lagging) load at rated current. The armature reaction is  (A) magnetizing (B) demagnetizing (C) cross-magnetizing (D) ineffective

asked May 17, 2018 in Synchronous machine by Shimroz123
0 answers 22 views

A d.c. shunt motor runs at no load speed of 1140 r.p.m. At full load armature reaction weakens the main flux by 5%. Whereas the armature circuit voltage drops by 10%. The full load speed of the motor is (a) 1200 r.p.m. (b) 1080 r.p.m. (c) 1040 r.p.m. (d) 1000 r.p.m.

asked May 25, 2018 in DC motor by Shimroz123
0 answers 28 views

 A DC shunt motor having unsaturated magnetic circuit runs at 1000 rpm with rated voltage If the applied voltage is reduced to half of the rated voltage, the motor will run at (A) 2000 rpm (B) 1000 rpm (C) 750 rpm (D) 500 rpm

asked Apr 14, 2018 in Electrical Engineering by Shimroz123
1 answer 23 views

A 10A DC Ammeter has a resistance of 0.1 Ω is to be extended to 50 A, the required shunt wire is A) Manganin wire of 20 m Ω B) Constantan wire of 20 m Ω C) Manganin wire of 25 m Ω D) Constantan wire of 25 m Ω

asked Jun 4, 2018 in Electrical Measurements and Instrumentation by Shimroz123
0 answers 16 views

A 4 pole lap wound dc shunt motor rotates at the speed of 1500 rpm, having a flux of 0.4 mWb and total number of conductors 1000. The value of e.m.f. will be:  (A) 100 Volts (B) 0.1 Volts (C) 1 Volts (D) 10 Volts

asked Apr 9, 2018 in Electrical Engineering by Shimroz123
1 answer 29 views

A 3 phase, 400 volts, 50 Hz, 100 kW, 4 pole squirrel cage induction motor with a rated slip of 2% will have a rotor speed of: (A) 1500 rpm (B) 1470 rpm (C) 1530 rpm (D) 1570 rpm

asked Apr 11, 2018 in Computer Engineering by Shimroz123
1 answer 18 views

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  (A) 0.354 (B) 0.372 (C) 0.90 (D) 0.955

asked May 18, 2018 in Power electronics converters by Shimroz123
1 answer 16 views

The dc motor, which can provide zero speed regulation at full load without any controller is  (A) series (B) shunt (C) cumulative compound (D) differential compound

asked May 17, 2018 in DC motor by Shimroz123
1 answer 15 views

In a 2 kW, 200 V, 1000 rpm. DC series motor the torque at full load was found to be 0.3 N -m. The torque at half full load in N -m is :

asked Apr 29, 2018 in Electrical Machine by Shimroz123
1 answer 28 views

A separately excited d.c. machine is coupled to a 50 Hz, three-phase, 4-pole induction machine as shown in the figure. The Dc machine is energized first and the machines rotate at 1 600 1pm. Subsequently the induction machine is also connected to a 50 Hz, three phase source, the phase sequence being consistent with the direction of rotation. In steady state

asked May 20, 2018 in DC machine by Shimroz123
1 answer 12 views

 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

asked Apr 11, 2018 in Electrical Engineering by Shimroz123
1 answer 35 views

The corona loss in a 50 Hz system is 0.25 kW/ph/km. At a frequency of 60 Hz, the corona loss would be   (a) 0.30 kW/ph/km (b) 0.36 kW/ph/km (c) 028 kW/ph/km (d) 0.21 kW/ph/km

asked May 13, 2018 in Power system by Shimroz123
1 answer 62 views

The corona loss of a 3-phase transmission line is 100 kW at 60 kV/phase and 25 kW at 50 kV/phase. The disruptive critical voltage is (A) 40 kV (B) 43.6 kV (C) 49.6 kV (D) 50 kV

asked Apr 25, 2018 in Electrical Engineering by Shimroz123
1 answer 52 views

The corona loss on a particular system at 50 Hz is 1 kw/phase per km. The corona loss on the same system with supply frequency 25 Hz will be?

asked Mar 27, 2018 in Power system by Shimroz123
1 answer 55 views

A shunt generator running at 1000 r.p.m. has generated e.m.f. as 200 V. If the speed increases to 1200 r.p.m., the generated e.m.f. will be nearly?

asked Mar 21, 2018 in DC generator by Shimroz123
1 answer 42 views

A 50 Hz, 4-pole, 500 MVA, 22 kV turbo-generator is delivering rated megavolt amperes at 0.8 power factor. Suddenly a fault occurs reducing in electric power output by 40%. Neglect losses and assume constant power input to the shaft. The accelerating torque in the generator in MNm at the time of fault will be  (A) 1.528 (B) 1.018 (C) 0.848 (D) 0.509

asked May 25, 2018 in Power system by Shimroz123
1 answer 24 views

An A.C current is given by i=100sin100. It will achieve a value of 50 A after (1) 1/600 sec (2) 1/300 sec (3) 1/1800 sec (4) 1/900 sec 

asked Apr 11, 2018 in Electrical Engineering by Shimroz123
1 answer 20 views

A three-phase, fully controlled thyristor bridge converter is used as line commutated inverter to feed 50 kW power 420 V dc to a three-phase, 415 V(line), 50 Hz ac mains. Consider dc link current to be constant. The rms current of the thyristor is  (A) 119.05 A (B) 79.37 A (C) 68.73 A (D) 39.68 A

asked May 18, 2018 in Power electronics converters by Shimroz123
2 answers 196 views

What happens to current flow in a capacitive circuit when the DC voltage across the capacitor is approximately equal to the source voltage?

asked May 29, 2018 in Capacitance by Shimroz123
1 answer 9 views

What will happen when a DC shunt motor is started with a load?

asked Jul 5 in DC motor by Shimroz123
1 answer 20 views

 If shunt generator delivers 100 A at 200 V, and the resistance of the shunt field and armature are 100 ohm and 0.01 ohm respectively, the generated e.m.f. will be : -  a) 212 V b) 205 V c) 210 V d) 201.02 V

asked Apr 11, 2018 in Electrical Engineering by Shimroz123
1 answer 14 views

Why does the speed of a DC shunt motor decrease as the load increases?

asked Jul 5 in DC motor by Shimroz123
1 answer 22 views

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  (A) 48.0% (B) 57.1% (C) 59.2% (D) 88.8%

asked May 17, 2018 in Electrical Machine by Shimroz123
1 answer 15 views

A 200 V DC machine supplies 20 A at 200 V as a generator. The armature resistance is 0.2 Ohm. If the machine is now operated as a motor at same terminal voltage and current but with the flux increased by 10%, the ratio of motor speed to generator speed is

asked May 8, 2018 in Electrical Machine by Shimroz123
1 answer 12 views

If the field circuit of a loaded shunt motor is suddenly opened?

asked Mar 26, 2018 in DC motor by Shimroz123
1 answer 24 views

A network is said to be under resonance when the voltage and the current at the network input terminals are (A) in phase (B) out of phase (C) in phase quadrature (D) in phase, and have equal magnitudes

asked Apr 28, 2018 in Network Analysis by Shimroz123
0 answers 21 views

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 

asked Apr 5, 2018 in Electrical Engineering by Shimroz123

Welcome to electronics2electrical.com here you can ask questions related to electrical, electronics, mechanical, telecommunication, instrumentation, computer, mathematics, physics etc.
Be respectful to all the members. Do not copy and paste the answers from other websites which have copyright content. While asking question give full details about it.

Categories

Most popular tags

power motor dc circuit transformer voltage current used system phase resistance factor synchronous load ac energy induction electric generator series frequency between speed capacitor use electrical meter line difference control type mosfet transmission magnetic plant high single instrument bjt unit source advantages function diode and machine winding field define torque parallel amplifier supply shunt thyristor motors electricity arduino maximum time relay armature problem value on transformers types coil diagram state flow ratio material three formula starting direction theorem method emf operating efficiency digital wave microprocessor test instruments inductance loss measure operation connected signal low applications effect single-phase network temperature working constant losses different law wattmeter measuring compare controlled breaker drive device logic rc full switch flux wire resistivity disadvantages free of materials machines angle force converter conductor transistor gain open protection scr core measurement number bridge principle generators reactance circuits negative the friction iron loop short pole battery conservation steam resistors hysteresis computer using analog lines secondary station gate a rectifier inverter linear induced relays nuclear capacitance basic characteristics design direct work rotor electronics ammeter forces diesel damping rlc connection factors capacitors minimum insulation moving regulation running self systems air fault range main stability quality starter igbt eddy alternator ideal rl average 3-phase plants arc thermal error fuzzy biasing dielectric pressure balanced superposition errors copper rotation feedback impedance measured electronic electrons charge inductive transfer explain start off back curve over solar is three-phase tariff locomotive peak bias zener engineering commutator surge conductors rating universal potentiometer density permanent mechanical transducer capacity memory adc excitation two fuse pure harmonics application semiconductor inductor internal pmmc reaction welding resonance traction permeability breakers rms designed electromagnetic si generation brushes switching capacitive shaded rate 1 distribution resistor methods delta star oscillator reluctance simplification algebra 8085 boolean weston dynamometer insulating strength installation definition fuel heating earth units

8,450 questions

7,047 answers

132 comments

3,084 users

...