Harmonic currents
Harmonic currents
(OP)
The presence of non-linear electrical loads in both commercial and industrial applications has dramatically increased, generating large harmonic currents. Can someone please tell me the examples of these loads






RE: Harmonic currents
RE: Harmonic currents
fluorescent lamp balasts cause harmonics.The harmonic-generating devices are also static convertors,inverters,
speed controllers etc.
RE: Harmonic currents
RE: Harmonic currents
A.Rash BScEE & PE
a_rash@bigfoot.com
RE: Harmonic currents
Light bulbs are not the only linear load. Resistive heating doesn't "generate" harmonics. Likewise a motor doesn't generate harmonics unless it is operating near saturation.
In general we can characterize or analyse system by measuring or predicting the THD of both the current and the voltage.
Nonlinear loads will draw current with high THD.
The impedance in the power supply will cause that nonlinear current to produce a smaller distortion of the system voltage. (lower THDv than THDi)
That distorted system voltage also effects other components. But in a linear load, the THD of that load current will be the same as the THD of the supply voltage. In nonlinear load the THD of the current will likely exceed the THD of the supply voltage.
As you move further "upstream" within a power supply, the effect of a given non-linear load upon the system voltage decreases. Harmonic voltage drop (which causes the voltage distortion) is related to the product of harmonic current and power supply impedance.
RE: Harmonic currents
1. Visit
http://www.pqtoday.com/downloads/pqtsum95.pdf
for some harmonics and power quality related content, including nonlinear loads.
2. Additional nonlinear loads are:
Rectifiers
Battery Chargers
Microwave Owens
Radars
Many pulse loads
Nonlinear resistors (thermistors, sensistors, thyrite, MOVs, etc.)
etc.