GATE EE
Electrical Machines
D.C Machines
Previous Years Questions

Marks 1

A 280 V, separately excited DC motor with armature resistance of 1 $$\Omega$$ and constant field excitation drives a load. The load torque is proporti...
A separately excited dc motor has an armature resistance R$$a$$ = 0.05⁡Ω. The field excitation is kept constant. At an armature voltage of 100 V, the ...
A 4-pole, lap-connected, separately excited dc motor is drawing a steady current of 40 A while running at 600 rpm. A good approximation for the wavesh...
A 4-pole, separately excited, wave wound DC machine with negligible armature resistance is rated for 230 V and 5 kW at a speed of 1200 rpm. If the sam...
A shunt-connected DC motor operates at its rated terminal voltage. Its no-load speed is 200 radian/second. At its rated torque of 500 Nm, its speed is...
A separately excited DC generator has an armature resistance of 0.1 $$\Omega$$ and negligible armature inductance. At rated field current and rated ro...
The no-load speed of a 230 V separately excited dc motor is 1400 rpm. The armature resistance drop and the brush drop are neglected. The field current...
A 4–point starter is used to start and control the speed of a
The dc motor, which can provide zero speed regulation at full load without any controller is
In a $$DC$$ machine, which of the following statements is true?
A dc series motor fed from rated supply voltage is overloaded and its magnetic circuit is saturated. The torque-speed characteristic of this motor wil...
In case of an armature controlled separately excited dc motor drive with closed loop speed control, an inner current loop is useful because it
The compensating winding in a dc machine
Ratio of the rotor reactance X to the rotor resistance R for a two-phase servomotor
A 1.8° step, 4-phase stepper motor has a total of 40 teeth on 8 poles of stator. The number of rotor teeth for this motor will be
A 4-pole lap-wound DC generator has a developed power of P watts and voltage of E volts. Two adjacent brushes of the machine are removed as they are w...
The torque speed characteristic of a Repulsion motor resembles which of the following dc motor characteristic?
Which type of motor is most suitable for computer printer device?
A $$4$$ pole dynamo with wave wound armature has $$51$$ slots containing $$20$$ conductors in each slot. The induced $$emf$$ is $$357$$ volts and the ...
A differentially compounded d.c. motor with interpoles and with brushes on the neutral axis is to be driven as a generator in the same direction with ...
A cumulative compounded long shunt motor is driving a load at rated torque and rated speed. If the series field is shunted by a resistance equal to t...
Neglecting all losses, the developed torque $$(T)$$ of $$d.c.$$ separately excited motor, operating under constant terminal voltage, is related to its...

Marks 2

A 200 V DC series motor, when operating from rated voltage while driving a certain load, draws 10 A current and runs at 1000 r.p.m. The total series r...
A 120 V DC shunt motor takes 2 A at no load. It takes 7 A on full load while running at 1200 rpm. The armature resistance is 0.8 Ω, and the shunt fiel...
A 220 V, 10 kW, 900 rpm separately excited DC motor has an armature resistance Ra= 0.02 Ω. When the motor operates at rated speed and with rated termi...
A separately excited DC generator supplies 150 A to a 145 V DC grid. The generator is running at 800 RPM. The armature resistance of the generator is ...
A 220 V DC series motor runs drawing a current of 30 A from the supply. Armature and field circuit resistances are 0.4 Ω and 0.1 Ω respectively. The l...
A DC shunt generator delivers 45 A at a terminal voltage of 220 V. The armature and the shunt field resistance are 0.01 Ω and 44 Ω respectively. The s...
With an armature voltage of 100 V and rated field winding voltage, the speed of a separately excited DC motor driving a fan is 1000 rpm, and its armat...
A DC motor has the following specifications: 10 Hp, 37.5 A, 230 V; flux/pole = 0.01 Wb, number of poles = 4, number of conductors = 666, number of par...
A separately excited DC motor runs at 1000 rpm on no load when its armature terminals are connected to a 200 V DC source and the rated voltage is appl...
A separately excited 300 V DC shunt motor under no load runs at 900 rpm drawing an armature current of 2 A. The armature resistance is 0.5 $$\Omega$$ ...
A 250 V dc shunt machine has armature circuit resistance of 0.6 $$\Omega$$ and field circuit resistance of 125 $$\Omega$$. The machine is connected to...
A 15kW, 230V dc shunt motor has armature circuit resistance of 0.4 $$\Omega$$ and field circuit resistance of 230 $$\Omega$$. At no load and rated vol...
A 220 V, 15 kW, 1000 rpm shunt motor with armature resistance of 0.25 Ω , has a rated line current of 68 A and a rated field current of 2.2 A. The ch...
A 220 V, DC shunt motor is operating at a speed of 1440 rpm. The armature resistance is 1.0 $$\Omega$$ and armature current is 10 A. of the excitation...
A separately excited DC motor runs at 1500 rpm under no-load with 200 V applied to the armature. The field voltage is maintained at its rated value. T...
A separately excited DC motor runs at 1500 rpm under no-load with 200 V applied to the armature. The field voltage is maintained at its rated value. T...
Figure shows the extended view of a $$2$$ pole $$dc$$ machine with $$10$$ armature conductors. Normal brush positions are shown by $$A$$ and $$B,$$ p...
A $$240V$$ $$dc$$ shunt motor draws $$15A$$ while supplying the rated load at a speed of $$80$$ $$rad/s$$. The armature resistance is $$0.5$$ $$ohm$...
A $$240V$$ $$dc$$ shunt motor draws $$15A$$ while supplying the rated load at a speed of $$80$$ $$rad/s$$. The armature resistance is $$0.5$$ $$ohm$...
A $$220V$$ $$DC$$ machine supplies $$20$$ $$A$$ at $$200V$$ as a generator. The armature resistance is $$0.2$$ ohm. If the machine is now operated as ...
Two magnetic poles revolve around a stationary armature carrying two coils ($$c_1-c'_1$$ , $$c_2-c'_2$$ ) as shown in Figure. Consider the instant whe...
In relation to DC machines, match the following and choose the correct combination. Group-I(Performance variables) (P) Armature emf (E) (Q) Developed...
A 50 kW dc shunt motor is loaded to draw rated armature current at any given speed. When driven (i) at half the rated speed by armature voltage contro...
The armature resistance of a permanent magnet dc motor is 0.8 $$\Omega$$. At no load, the motor draws 1.5 A from a supply voltage of 25 V and runs at ...
A 8 pole, DC generator has a simplex wave-wound armature containing 32 coils of 6 turns each. Its flux per pole is 0.06 Wb. The machine is running at ...
A dc series motor driving an electric train faces a constant power load. It is running at rated speed and rated voltage. If the speed has to be brough...
A 200 V, 2000 rpm, 10A, separately excited d.c. motor has an armature resistance of 2 $$\Omega$$. Rated d.c. voltage is applied to both the armature a...
An electric motor with 'constant output power' will have a torque speed characteristic in the form of a
A 240 V dc series motor takes 40A when giving its rated output at 1500 rpm. Its resistance is 0.3 ohms. The value of resistance which must be added to...
A permanent magnet dc commutator motor has a no load speed of 6000 rpm when connected to a 120V dc supply. The armature resistance is 2.5 ohms and oth...
A DC shunt motor is running at 1200 rmp, when excited with 220 V DC. Neglecting the losses and saturation, the speed of the motor when connected to a ...
A 240 V d.c. shunt motor with an armature resistance of 0.5 $$\Omega$$ has a full load current of 40 A. Find the ratio of the stalling torque to the f...
Match the following List-I (Test) (A) No load and blocked rotor test (B) Sumpner’s test (C) Swinburn’s test List-II (Machine) (1) Transformer (2) In...

Marks 5

A $$230V,$$ $$250$$ $$rpm.$$ $$100A$$ separately excited $$dc$$ motor has an armature resistance of $$0.5\,\Omega .$$ The motor is connected to $$230V...
In a $$dc$$ motor running at $$2000$$ $$rpm,$$ the hysteresis and eddy current losses are $$500$$ $$W$$ and $$200$$ $$W$$ respectively. If the flux re...
A $$dc$$ series motor is rated $$230V,$$ $$1000$$ $$rpm,$$ $$80$$ $$A$$ (refer to Figure). The series field resistance is $$0.11\,\Omega ,$$ and the a...
A separately excited $$DC$$ shunt motor is driving a fan load whose torque is proportional to the square of the speed. When $$100$$ $$V$$ are applied ...
A $$DC$$ shunt generator delivers $$60$$ $$KW$$ at $$240$$ $$V$$ and $$360$$ $$rpm.$$ The armature and field resistances are $$0.015\,\,\,\Omega $$ an...
A $$200V$$, $$10$$ $$kW$$ lap-wound $$d.c.$$ generator has $$10$$ poles and $$500$$ conductors on it's armature. If the pole face covers $$80\% $$ o...
A $$5$$ $$kW,$$ $$200V$$ $$d.c.$$ shunt motor has an armature resistance of $$1$$ $$ohm$$ and shunt field resistance of $$100$$ $$ohms.$$ At no-load, ...
The field coil of a two-pole $$d.c.$$ series motor is made up of two identical sections In one case $$(i)$$ of two sections of the field coil are conn...
At $$50\% $$ of full load, the armature current drawn by a $$d.c.$$ shunt motor is $$40$$ A when connected to a $$200$$ $$V$$ $$d.c.$$ mains. By decre...
A separately excited $$d.c.$$ motor has an armature resistance of $$0.5$$ $$ohm.$$ It runs off a $$250$$ $$V$$ $$d.c.$$ supply drawing an armature cur...
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