1. BY IFTEKHAR
E1 - 11213
M.H.S.S.P

2. WHAT IS HARMONICS?
 “A COMPONENT FREQUENCY OF A HARMONIC MOTION
OF AN ELECTRO MAGNETIC WAVE I.E AN INTEGRAL
MULTIPLE OF FUNDAMENTAL FREQUENCY”.
US FUNDAMENTAL FREQUENCY ARE 50Hz.

3. WHAT CAUSES OF
HARMONICS ?

NON-LINEAR LOAD
(CURRENT IS NOT PROPOTIONAL TO VOLTAGE)

4. NON-LINEAR LOAD
 NON-LINEAR LOADS ARE
SWITCHED ON ONLY PART
OF THE CYCLE.
EG:DIODE ,
TRANSISTOR , ETC.
GRAH SHOWS THE RELATION
BETWEEN VOLTAGE & CURRENT

5. EFFECT OF HARMONIC ON WAVE
FORM

6. SOURCE OF
HARMONICS
 Converters,
 Devices which includes semi-conductor elements,
 Generators,
 Motors,
 Computers,
 Electronic ballasts,
 Switching power supplies,
 Welding machines,
 Control circuits,
 HVDC transmission systems,
 Electrical Communication systems.
 Transformers

7. WHAT DO HARMONIC
DO ?
 HARMONIC ARE CARRIED THROUGH THE SYSTEM
FROM THE SOURCE CAN BE NEARLY DOUBLE THE
AMOUNT OF CURRENTON THE NEUTRAL CONDUCTOR
IN 3 PHASE 4 WIRE DISTRIBUTION SYSTEM.
OVERALL ELECTRICAL SYSTEM & POWER QUALITYIS
AFFECTED BY THE HARMONICS.

8. EFECT OF HARMONIC ON
SUPLY
 DISORTED VOLTAGE.
 OVERHEATED OF TRENSFORMER &
MOTOR
 HEATING OF NEUTRAL CONDUCTOR.

9. EFFECT ON
TRANSFORMER
 Transformer overheating and potential
insulation failure result from several
conditions caused by harmonics:
 Increased skin and proximity effects
 Harmonics circulating in the primary winding
 Increased hysteresis losses
 Increased eddy current losses

10. Solutions
Power filters .
Isolation transformer .
Line reactors.
Online UPS.
HARMONIC CONVERTOR
19-10-2005 10

11. HOW CAN ELIMINATE
6-pulse converter
note the level of distortion
and steep current rise.
12-pulse converter
the waveform appears more
sinusoidal, but still not very
smooth.
18-pulse converter
virtually indistinguishable
from the source current
waveform.

12. CONCLUSION
 The harmonic distortion principally
comes from Nonlinear-Type Loads.
 The application of power
electronics is causing increased
level of harmonics due to
Switching!!
 Harmonic distortion can cause
serious Failure/Damage problems

13. QUESTIONS
?