harmonics 130307055153-phpapp02
TRANSCRIPT
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.
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 ?