The Power supply we are getting at our residential & commercial areas from power generating utility, All are alternating current. In this post we will explain alternating current along with its important parameters.
ALTERNAING CURRENT(AC)
An alternating current continuously changes its position with respect to time. It also changes its direction in opposite periodically at fixed intervals.
"An AC sinusoidal waveform shown with a GIF below"
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| GIF shows an AC sine wave |
SYMBOL OF AC
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| AC symbol marked on Clamp meter 302+ by FLUKE |
IMPORTANT TERMS OF ALTERNATING CURRENT
Alternating current has particular Frequency, waveform & magnitude Which define the type of alternating current. We are going to discuss all these terms one by one.
FREQUENCY
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One complete cycle of sinusoidal alternating current
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Frequency means how many times waveform making a cycle with respect to time. A Sinusoidal wave shown above, In which Both positive & negative half constitute a complete cycle.
In short, Frequency is a Number of cycles per second. The unit of frequency is Hz. In India, frequency standard is 50 Hz.
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Nameplate of monoblock pump
Rated frequency 50Hz |
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Name plate of Air conditioner indoor unit by DAIKIN
Shows rated voltage 230VAC at Rated frequency of 50Hz
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Due to the frequency term, Power flow in alternating current is time dependent Which makes the addition of phase angle or power factor term in power calculation of alternating current.
WAVEFORM
The shape, the path alternating current follows while traveling is known as Waveform. A sinusoidal waveform already been discussed above while An AC triangular waveform been shown below.
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| Triangular AC waveform |
MAGNITUDE
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| Specified voltage Standard(RMS magnitude) with AC symbol |
Magnitude defines the level of amplitude of alternating current. Both AC & DC waveform shown below, In pure DC wave, the magnitude remains the constant. So, It will become easy to consider the magnitude which is the Vmax. But in case of AC, How do we define the magnitude Which is changing continuously ?
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| Pure DC waveform |
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| AC waveform |
In an complete cycle of AC, It get at its maximum point two times while three times it getting zero. It is having a average value also. To define the magnitude of AC, A term RMS (Root Mean Square) been introduced which is the root mean of squared instantaneous values. RMS value of alternating current produces the same amount of power as of DC current of same voltage.
Vrms= √[(x0²+x1²+x2² . .+xn²)/n]
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| Root mean Square of sinusoidal alternating current |
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| 3510 True RMS Power Meter by MECO |
IMPORTANCE OF ALTERNATING CURRENT
Electrical motors, Electrical generators & Electrical transformers are the most important electrical machines. All these machines are working on alternating current.
In transmission & distribution AC participates a big role. It is easy & efficient to change the AC power supply through transformer.
Hope, You like the post. If you have any doubt, Suggestion or query please do comments !
