8/2/2019 Presentetion Dc Motor 110

1/16

LOGO

DC MOTOR

ELECTRICAL MACHINE

8/2/2019 Presentetion Dc Motor 110

2/16

Assigned topics

TYPES OF DC MOTOR WORKING PRINCIPLE OF DC MOTOR

CONDITION OFMAX.POWER

DERIVATION OF BACK EMFEQUATION

BACK EMFTOPICS

8/2/2019 Presentetion Dc Motor 110

3/16

Syed Muhammad zaidi TYPES OF DC MOTOR

Syed Muhammad zaidi TYPES OF DC MOTOR

Group members

Muhammad ali

1

2 WORKING PRINCIPLE OF DC MOTOR

RASHID HAMEED Condition of MAX POWER

RASHID HAMEED Condition of MAX POWER

Rehman ali back emf

3

4

Rizwan saeed application of dc motor

Rizwan saeed application of dc motor5

8/2/2019 Presentetion Dc Motor 110

4/16

8/2/2019 Presentetion Dc Motor 110

5/16

Here I, brief series wound motor

In series wound motor, field coil is connected

in series with armature.

Because of series connectivity, its armature

and field current is identical.The advantage of a series-wound motor is that

it develops a large torque and can be operated

at low speed.

.

8/2/2019 Presentetion Dc Motor 110

6/16

Shunt wound motor

In shunt motor, field coil is connected in

parallel with armature.

It is used when starting torque is low and

increases with motor speed.

www.themegallery.co

8/2/2019 Presentetion Dc Motor 110

7/16

Compound motor

The compounded motor is desirable for a varietyof applications because it combines thecharacteristics of a series-wound motor and a shunt-

wound motor. The compounded motor has a greatertorque than a shunt motor due to the series field.

8/2/2019 Presentetion Dc Motor 110

8/16

Ali come on the stage please

And present your assigned

topic.

.

8/2/2019 Presentetion Dc Motor 110

9/16

Working Principle of DCMotor

Working Principle of DC Motor

When the coil is powered, a magnetic field is generated around the

armature. The left side of the armature is pushed away from the left

magnet and drawn towards the right, causing rotation. When the coil

turns through 900, the brushes lose contact with the commutator andthe current stops flowing through the coil. However the coil keeps

turning because of its own momentum.

.

8/2/2019 Presentetion Dc Motor 110

10/16

Mr. Rashid

come on thestage please.

8/2/2019 Presentetion Dc Motor 110

11/16

Condition For Maximum Power

The mechanical power developed by the motor

is Pm= EbIaNow Pm=VIa -I

2aRa

Since, V and Ra are fixed, power developed bythe motor depends upon armature current. For

maximum power, dPm/dIa should be zero.

dPm/dIa = V 2IaRa

a a =

Now, V = Eb + IaRa =Eb + V/2therefore Eb= V/2

Hence mechanical power developed by the

motor is maximum when back e.m.f. is equal to

half the applied voltage.

V = applied voltage

Eb = back e.m.f.

Ra = armature resistance

Ia = armature current

8/2/2019 Presentetion Dc Motor 110

12/16

Mr. Rehman

come on thestage please.

8/2/2019 Presentetion Dc Motor 110

13/16

Back emf

Back e.m.f (or) counter e.m.f:

When a D.C supply is given to dc motor its

armature starts rotating.The armature rotates

and cuts the static magnetic flux produced bythe field magnets.Therefore emf is induced in

the armature conductors (Faradays law of

electromagnetic induction ).As per Lenz law

t s n uce em opposes t e supp y

voltage.Hence the emf induced in the armature

is called Back emf (or)counter emf(Eb).Back

emf induced in the armature of the dc motor

Eb = NZP/60A

8/2/2019 Presentetion Dc Motor 110

14/16

Mr. RIZWAN

come on thestage please.

8/2/2019 Presentetion Dc Motor 110

15/16

Applications of DC Motors:

1. D.C Shunt Motors:

Industrial use:Lathes

DrillsBoring mills

Shapers

Spinning and Weaving machines.

. .

compound motors are rarely used because of itspoor torque characteristics.

Industrial uses:

Presses Shears

Reciprocating machine.

8/2/2019 Presentetion Dc Motor 110

16/16

LOGO