HARMONICS

BY IFTEKHAR

E1 - 11213

M.H.S.S.P

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.

WHAT CAUSES OF HARMONICS ?

NON-LINEAR LOAD

(CURRENT IS NOT PROPOTIONAL TO VOLTAGE)

NON-LINEAR LOAD

GRAH SHOWS THE RELATION BETWEEN VOLTAGE & CURRENT

NON-LINEAR LOADS ARE SWITCHED ON ONLY PART OF THE CYCLE.

EG:DIODE , TRANSISTOR , ETC.

EFFECT OF HARMONIC ON WAVE FORM

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

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.

EFECT OF HARMONIC ON SUPLY DISORTED VOLTAGE.

OVERHEATED OF TRENSFORMER & MOTOR

HEATING OF NEUTRAL CONDUCTOR.

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

HOW CAN ELIMINATE 6-pulse converter

12-pulse converter

18-pulse converter

note the level of distortionand steep current rise.

the waveform appears moresinusoidal, but still not very smooth.

virtually indistinguishablefrom the source currentwaveform.

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

QUESTIONS ?