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Please let me know each order of harmonic, which one represented of Motors, transformers, Lightings, Resistive Load, Inductive Load, Capacitors, UPS and etc. As we know generally harmonics can recorded by Power Analyzer Equipment but It's not explain each load be represented by what level harmonics. example harmonic order 1st. - 40th. what is order harmonic indicate Motors distortion? is it order 1st., 3rd., or 5th...etc.

2007-06-13 13:51:39 · 3 answers · asked by JHONNY KARUNDENG PUTIN AL-QIRAZY 1 in Science & Mathematics Engineering

3 answers

Harmonic currents and harmonic voltages on the ac system (either distribution or transmission) are a result of nonlinearities in the components.

Normally, generation sources have very low harmonic content by design and by standards. They are either 60 Hz or 50 Hz. This is the 'fundamental' or '1st order' of the system. 2nd harmonic, naturally, is twice the fundamental frequency. 3rd is
3x the fundamental, etc.

Resistive loads, such as resistive heating and incandescent lamps do not produce harmonic currents, because the current is directly proportional to the voltage at every instant in time.

Capacitors and inductors normally do not produce harmonics, since they are fundamentally linear devices. However, inductances with ferromagnetic (i.e. iron or steel) cores can be driven into saturation. When saturation occurs in transformers due to overexcitation, this typically results in 5th harmonic currents. When transformers are initially energized, remanent flux in the ferrous core can cause asymmetrical inrush currents. These are typically characterized by the presence of 2nd harmonics currents.

Other sources of harmonic currents are the various switching devices, such as rectifiers, inverters, and converters. The little power supply units (for converting ac to dc) in computers and personal electronics usually draw load current rich in harmonics.

If the power system were only resistive & inductive, and saturation was avoided (it mostly is), a little bit of harmonics would not cause too much aggravation. However, if the harmonic content of the load current gets too high, it can cause excessive heating of the circuit components, and it can cause harmonic voltage distortion through its interaction with the transformers.

All of this is said without even mentioning resonance. When capacitors exist on the system (they always do in some form or other), there is the opportunity for minimally-damped resonances. If these resonant conditions occur at frequencies that also have a source of excitation (typically 5th, 7th, 11th, 13th, etc), and the resonance is minimally-damped, things get really messy in a hurry. Lots of harmonic current sloshes back and forth between the capacitance and inductance, resulting in excessive voltages and equipment damage.

In the U.S., the standard for harmonics on power systems is IEEE Standard 519 - 1992. There are plenty of technical articles and papers available on the web that can provide a good explanation.

2007-06-13 14:43:46 · answer #1 · answered by Steve W 5 · 0 0

It's not quite as simple as you suppose.
Harmonics are the result of resonance which changes with other conditions.
I have a few simple partial answers for you:
1. Resistive loads have a power factor of unity, (current matches voltage), and thus do not produce harmonics, (except momentarily when switched on & off).
2. SCRs, sometimes used in power supplys, (UPS & electronic ballasts and dimmers), will sometimes resonate with the line producing harmonics depending on the switching points relation to the waveform.
3, Capacitors and inductances, (Motors & transformers), where current does not match voltage will resonate to varying degrees.

2007-06-13 14:18:54 · answer #2 · answered by Irv S 7 · 0 2

You need to buy a book. Linear components, (resistors, capacitotrs, inductors, transformers) can never add harmonics to a system. Only nonlinear active components can

2007-06-13 14:33:35 · answer #3 · answered by Gene 7 · 0 0

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