Harmonics are integer multiples of the fundamental supply frequency that distort the waveform of the current or voltage. They are caused by non-linear loads where the current is not directly proportional to the voltage, such as diodes and transistors. The effects of harmonics include overheating of transformers and motors, increased neutral conductor heating, and reduced power quality and reliability of the electrical system. Harmonics can be mitigated by using power filters, isolation transformers, line reactors, online UPS systems, or harmonic converters.

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
?