45
Matrix
Protection and Control Units
Linear Loads:
The AC loads are called linear loads when the current and voltage resultant waveform is sinusoidal in nature (i.e. not
distorted). Also the current at any instant is proportional to the voltage at that instant.
Thus in linear systems there are no harmonic components in current and the voltage waveforms.
e.g. Heaters, Power factor improvement capacitors, etc.
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Ir
Iy
Ib
3 PHASE FUNDAMENTAL WAVE
RESULTANT CURRENT I = Ir+Iy+Ib = 0
CURRENT WAVE FOR LINEAR LOAD
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The AC loads which cause the current waveform to distort from the normal sinusoidal nature are called as non-linear
loads. Current distortion leads to the distortion of the voltage waveform also. Thus the voltage and current are no
longer proportional.
The distorted current and the voltage waveforms can be decomposed into pure sinusoidal and associated
frequencies of the higher order through Fourier Transformation.
Harmonic spectrum gives a clear analysis of amount and order of the harmonics present in the system, which helps in
the designing the filter for the system.
e.g. SMPS, Rectifiers, PLC, Electronic Ballasts, Laser Printers, Computers, etc.
RESULTANT CURRENT
WITH 3rd HARMONICS
RESULTANT CURRENT I = Ir+Iy+Ib
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CURRENT WAVEFORM FOR NON-LINEAR LOAD
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3 6 9 12 15 18 21 24 27
Component
R-Phase
23:59
%
HARMONIC SPECTRUM
46
Matrix
Protection and Control Units
Harmonics
are basically the sinusoidal component of the periodic wave with frequency that is an integral multiple of
the fundamental frequency.
Harmonics content purely determines the quality of power. Having harmonics in the system will affect the system
and the severity of effect on the system/equipment will depend on the stiffness of the system and the amount of the
harmonic pollution.
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:
• Non-linear loads generate current harmonics
• Harmonic currents flow largely through capacitors
• Harmonic currents also flow through network
• The flow of harmonic currents causes voltage harmonics
• Harmonics are thus injected to other linear loads connected in the same bus
• Harmonics injected into the network flow towards other users connected to the network
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:
•
Equipment using switched mode power supply:
4
Television
4
Computers, other IT loads
•
Equipment using power electronic devices:
4
AC & DC drives
4
Frequency converters
4
Rectifiers
4
Arc & induction furnaces
4
UPS
Summary of Contents for OMEGA
Page 2: ...Stabilise systems with technology ...
Page 4: ...Change course quickly ...
Page 6: ...Match performance with prudence ...
Page 8: ...Adopt technological brilliance ...
Page 10: ...Keep an eye on upkeep ...
Page 26: ...Matrix Protection Control Units T UW M X4 5 ...
Page 70: ...Accessories ...
Page 84: ...Control Circuit Wiring ...
Page 92: ...Mounting Termination ...
Page 135: ...SP 50567 R5 ...
