Harmonics: Enemy of true sinusoidal wave

Harmonics: Enemy of true sinusoidal wave

In a perfect power system, the voltage supplied to user, and the supplied load current are exactly sine waves. In practice, notwithstanding, conditions are never perfect, so these waveform are sometimes distorted. This deviation from ideal sinusoidal waveform is  expressed as harmonic distortion of voltage and current waveform.

Harmonic signals are integer multiple of fundamental frequency of original signal. for example a signal of fundamental frequency 50 Hz will have its harmonic components of 3rd and fifth order with frequencies of 150 hz and 250 hz respectively.

Bad Effects of  Harmonics:

• Effects on the power system itself 

Causes over heating and thermal loss of life great challenge for motors and transformers.

•  Effects on consumer load 

Causes thyristor firing errors in inverter and SVC installations. performance of consumer devices and machines is adversely affected.

• Effects on communication circuits 

Distortion in communication signals may result in distorted demodulated signal.

•  Effects on revenue billing 

Harmonic voltage distortion can impact charging by bringing mistake into kilowatt  hour metering frameworks that depend upon correct acumen of the voltage zero. Also, of  course harmonic current wholes with central current requested by facility loads to  straightforwardly expand net billable kilowatt request and kilowatt hour utilization charges

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What Actually Power Factor Is?

 Power Factor is a measure of how productively electrical energy is utilized. The perfect Power Factor is
solidarity, or one. Anything less than one, (or 100% productivity),  implies that additional force is instructed to attain the true  errand nearby. This additional power is regarded as Reactive Power, which  tragically is important to give a magnetizing impact  needed by machines and other inductive loads to perform  their coveted capacities. Be that as it may, Reactive Power can likewise  be translated as watt-less, magnetizing or squandered power what's more an additional load on the power supply.

     It is measured as cosine of angle between voltage and current as depicted in the below figure.

It is clear from above example that due to inductive and capacitive loads power factor lags and leads respectively. reactive power comes into existence due to power factor. in capacitive loads reactive power is supplied to source and in inductive load reactive power is absorbed by load means supplied by source.

Above image shows best analogy of active and reactive power. Actually reactive power causes losses in system. In above figure fane (kvar) is reactive power liquid in cup can be considered as active power (kw) and KVA is apparent power.


Benefits of Power Factor Correction

1.  Power consumption reduced
2.  Electricity bills reduced
3.  Electrical energy efficiency improved
4.  Extra kVA availability from the existing supply
5.  Transformer & distribution equipment  losses are reduced
6.  Minimised voltage drop in long cables

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