what is generator | Motor | FAQ

Definition of the generator and how many types.

A generator is a machine that converts mechanical energy into electrical energy.
How to create energy?

As low of faraday, if you keep a wair in rotating magnet file (EMF) electric motive forces are induced.

Ther are two type of genereter
1-AC genereter

Parts ac generator
1-Permanent magnet
2-Slip rings
3-Carbon Brush
4-armchair
What is Permanent magnet
A permanent magnet is a magnet that does not lose his property.

What is a temporary magnet?

It is a magnet created by humans. take some wire and round with an iron pice with an insulator. Then you flow current in this conductor. when you keep a piece of iron near, you see the iron pice attract.

What is Slip rings?

Slip rings are electrical connections. wont to transfer power to and from the rotor. it's consists of a circular conducting material Slip rings connected to the rotor windings and insulated from the shaft. Brushes ride on the connection because the rotor rotates. The electrical connection to the rotor is formed by connections to the brushes.

What is Carbon Brush?

It is a component used to a stationary and rotating parts of a generator. the carbon brush is fixe and collects the current on rotating shaft.

what is an armature?

the armature is rotating devise palace on a magnetic field.
when cutting the magnetic line of force and current is induced.


What is the ac generator?

All think the same about AC generator but, if you collect the current using commuter is called DC generator, ac change magnitude but not change magnitude.

What is the motor?
Moter is a machine that converts electrical energy into mechanical energy.
Type of motor

Ther are many types of motor
Two types of motors

• DC motors
• AC motors

How many types of   DC motor?

2 types of DC motor

• - Brushless
• - Brushed

How many types of brushed motor?

Fore type of brushed motor

• Series wound
• Shunt-wound
• Compound wound
• Permanent magnet

How many types of AC motor?

Two types of AC motor

• - Synchronous
• - Induction

Type of induction motor
Two types of induction motor

• - single phase
• - three-phase

Mcq for Generator

• The yoke of a d.c. the machine is made of...

1. Silicon steel
2. Soft iron
3. Aluminum
4. Cast steel

Ans-(D)

• The armature of a d.c. the machine is made of...

1. Silicon steel
2. Wrought iron
3. Cast steel
4. Soft iron

Ans-(A)
3-The coupling field between electrical and mechanical systems of a d.c. machine is...

1. Electric field
2. Magnetic field
3. Both electric and magnetic field
4. None of the above

Ans-(B)
4-The real working part of a dc machine is

1. commutator
2. field winding
3. armature winding
4. none of the above

Ans-(3)
5-D.c machines are most common.

1. 2-pole
2. 4-pole
3. 6-pole
4. 8-pole

Ans-(1)
6- The armature winding of a D.c machine is placed on the rotor to...

1. Save iron
2. Reduce losses
3. Facilitate commutation
4. Reduce armature reaction

Ans- (3)
7- The yoke of a DCL machine carries … pole flux

1. The
2. One-half of
3. Two times the
4. None of the above

Ans-(2)
8- A 4-pole dc machine has------ magnetic circuits.

1. 2
2. 8
3. 4
4. None of the above

Ans-(3)
9-the field structure of a dc machine uses

1. Salient-pole arrangement
2. Non-salient pole
3. Both(A)&(B)
4. None of the above

Ans-(1)
10- small Dc machines generally have poles

1. 4
2. 6
3. 2
4. 8

Ans-(3)

MCQ for  Motor

1-When tow series motors are connected in parallel, the resultant speed is

1. More than the normal speed
2. Less than the normal speed
3. Normal speed
4. Zero

Ans-(3)
2- what will happen if the back emf(Electro-Motive force) of a dc motor vanishes suddenly?

• The motor will stop
• The motor will continue to run
• The armature may burn
• The motor will run noisily
• Ans- The armature may burn

3- Differentially compound dc motor can find

1. a) High starting torque
2. b) Low starting torque
3. c) Variable speed
4. d) Frequent on-off cycles

    Ans-(a)
4-   The Dc motor has got maximum self-loading property

1. a) Series motor
2. b) Shunt motor
3. c) Cumulatively compound motor
4. d) Differentially compound motor

Ans- (D)
5- the starting resistance of a dc motor is generally

1. a) Low
2. b) Around 500 ohm
3. c) 1000 ohm
4. d) Infinity

Ans-(A)
6- which motor is generally preferred for cranes and hoists?

1. a) Series motor
2. b) Shunt motor
3. c) Cumulatively compounded motor
4. d) Differentially compounded motor

Ans-Series motor
7- the speed of a dc series motor is

1. a) Proportional to the armature current
2. b) Proportional to the square of the armature currents
3. c) Proportional to the field current
4. d) Inversely proportional to the armature current

Ans- (D)
8- If the field of dc shunt motor gets opened while the motor is running

1. a) speed of the motor will be reduced
2. b) The armature current will be reduced
3. c) motor will attain dangerously high speed
4. d) The motor will continue to run at constant speed4

Ans-(C)
9- IN dc machine fractional pitch winding is used

1. a) To improve colling
2. b) To reduce copper losses
3. c) To increase the generated emf
4. d) To reduce the sparking

Ans- (D)
10- In a dc shunt motor, under the maximum power, the current in the armature will be

1. a) Almost negligible
2. b) Rated full-load current
3. c) Lass than full- load current
4. d) More than full-load current

Ans-(D)
11- which dc motor is preferred for an elevator

1. a) Shunt motor
2. b) Series motor
3. c) Differentially compound motor
4. d) Cumulative compound motor

Ans- (D)
12- Which dc motor will have the least percentage increase of input current, for the same percentage increase in the torque?

1. a) Shunt motor
2. b) Series motor
3. c) Cumulative compound motor
4. d) Separately excited motor

Ans-(B)
13- which of the following motors will choose to drive the rotary compressor?

1. a) Dc shunt motor
2. b) Dc series motor
3. c) Universal motor
4. d) Synchronous motor

Ans- (D)
14 – which one of the following is not the function of pole shoes in a dc machine

1. a) To reduce eddy current Los
2. b) To support the field coils

Ans-(A)
15- If the terminals of armature of dc motor are interchanged, this action will offer the following kind of braking

1. a) Regenerative braking
2. b) Pugging
3. c) Dynamic braking
4. d) Not

Ans-Pugging
16 – the armature voltage control of dc motor provides

1. a) Constant voltage drive
2. b) Constant current drive
3. c) Constant torque drive
4. d) Not

Ans- Not
17 – which of the following application requires high starting torque

1. a) Lathe machine
2. b) Centrifugal pump
3. c) Locomotive
4. d) Air blower

Ans – (C)
18 – which of the following can be used to control the speed of a dc motor?

1. a) Thermistor
2. b) Thyristor
3. c) Thyratron
4. d) Transistor

Ans – (B)
19- a direct online starter is used for starting motors

1. a) Up to 5HP
2. b) Up to 10HP
3. c) Up to 15HP
4. d) Up to 20HP

Ans-(A)
20 – The Plugging give s the

1. a) Zero torque braking
2. b) Smallest torque braking
3. c) Highest torque braking
4. d) Not

Ans- (C)