Electrical Engineering · Question Bank

DC Generators

196 questions · page 5 of 10. Answer in your head first, then check the solution.

📘 EE Mock Board Exam

TypeAll 196 Problem solving 69 Objective 127

DifficultyAll 196 Easy 146 Medium 41 Hard 9

Exam

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#81📜 EE Pre-Board August 2017📘 PowerhouseEasy

In a shunt generator the voltage builds up until constrained by

Aarmature reaction

Bfield resistance

Csaturation of iron

Dbrush drop

#82📜 EE Pre-Board August 2017📘 PowerhouseEasy

The series field of a short-shunt compound dc generator is excited by ______ current.

Aarmature

Bshunt field

Cno

Dload (line)

#83📜 EE Pre-Board March 2018📘 PowerhouseEasy

In dc machines, lap winding is used for

Ahigh voltage low current

Blow voltage low current

Chigh voltage high current

Dlow voltage high current

#84📜 EE Pre-Board March 2018📘 PowerhouseEasy

An 8-pole lap wound dc generator has 1,000 armature conductors, flux of 20 mWb per pole and emf generated is 400 v. What is the speed of the machine?

A1,000 rpm

B1,800 rpm

C1,200 rpm

D1,500 rpm

#85📜 EE Pre-Board March 2018📘 PowerhouseEasy

The number of parallel paths in a simplex lap winding is equal to

Bnumber of poles

Cnumber of pairs of poles

#86📜 EE Pre-Board August 2018📘 PowerhouseEasy

A 4-pole wave wound generator has 220 coils of 10 turns each. The resistance of each turn is 0.02 Ω. Find the resistance of the armature winding.

A11 Ω

B22 Ω

C0.2 Ω

D0.44 Ω

#87📜 EE Pre-Board August 2018📘 PowerhouseEasy

How many commutator bars does a 6-pole dc generator with 4 coil sides per slot and 20 slots per pole have?

A60

B120

C240

D480

#88📜 EE Pre-Board August 2018📘 PowerhouseEasy

The dummy coil in dc machines is used to

Aeliminate reactance voltage

Beliminate armature reaction

Cbring about mechanical balance of armature

Deliminate harmonics developed in the machine

#89📜 EE Pre-Board August 2018📘 PowerhouseEasy

An 8-pole triplex wave-wound armature carries a total of 660 amperes. If there are 8 brush arms, calculate the current in each armature conductor.

A110 A

B66 A

C22 A

D11 A

#90📜 EE Pre-Board August 2018📘 PowerhouseEasy

Residual magnetism is necessary in a

Aseparately excited generator

Bself-excited generator

Cboth of these

Dnone of these

#91📜 EE Pre-Board August 2018📘 PowerhouseEasy

With reference to armature windings, wave windings are often called _______ windings.

ACascade

BSeries

Cparallel

Dring

#92📘 EE Pocket Reviewer RojasEasy

The yoke of a dc machine is made from which of the following?

ASilicon steel

BAluminum

CSoft iron

DCast steel

#93📘 EE Pocket Reviewer RojasEasy

Which one is the function of the pole in a dc machine?

ATo support the field coils

BTo spread out the flux

CTo reduce the reluctance of the magnetic path

DAll of these

#94📘 EE Pocket Reviewer RojasEasy

In dc machines the mechanical losses are primarily dependent on which of the following?

ACurrent delivered

BVoltage induced

CSpeed

DFlux density

#95📘 EE Pocket Reviewer RojasEasy

Which of the following is the excitation current of the series field in a long-shunt compound dc generator?

AArmature current

BShunt field current

CLoad current

DExternal current

#96📘 EE Pocket Reviewer RojasEasy

What is the reason why a separately-excited dc generator is no longer used today?

AIt is an expensive machine

BThe terminal voltage drops considerably with load

CA separate dc source is required for its field circuit

DIt is only available in low kW rating

#97📘 EE Pocket Reviewer RojasEasy

Shunt generators are the most suited for stable parallel operation due to which of the following voltage characteristics?

ALinear

BIdentical

CRising

DDrooping

#98📘 EE Pocket Reviewer RojasEasy

In dc machines, the armature windings are placed on the rotor because of the necessity for which of the following?

ACommutation

BGeneration of voltage

CDevelopment of torque

DElectro-mechanical energy conversion

#99📘 EE Pocket Reviewer RojasEasy

What is the reason why, the coil span of a dc armature winding must be equal to the pole pitch?

ATo save the length of the coil used for the windings

BTo distribute the windings uniformly under the different poles

CTo ensure the addition of emfs for consecutive turns

DTo make the machine deliver more current at a definite voltage

#100📘 EE Pocket Reviewer RojasEasy

What is the terminal voltage of a series generator running at rated speed and at no load?

AZero

BRated voltage

CMore than its rated voltage

DA very little voltage

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