Aircraft’s electrical supply is at the 400Hz frequency.Let’s see the reason behind using a higher frequency.
Aircrafts are heavy and carry heavy weights. Its speed depends on its weight.Lesser the weight, higher speeds can be achieved.
Advantage Of Running An Electrical System At 400 Hz
The Main advantage of running an electrical system at 400 Hz rather than 50 or 60Hz is that the power supplies becomes smaller and lighter.So The area of the cross-section of electric machines is reduced.So smaller the size the electrical machines lesser will be the weight. And Also, this benefit is important aboard aircraft since space is always limited, and it is important to minimize weight in order to maximize performance.
Let’s verify,
consider a transformer its emf equation is given by
E1 = 4.44fN1 Øm
Now, Øm= BmA
E1 = 4.44fN1BmA
Where E=Applied Usually Primary RMS voltage
f=frequency [Hz]
N=turns on the winding, where the voltage E is applied
A=cross-sectional-area enclosed by the winding
Bm = The Maximum flux density
From the equation, You can note that the area of cross-section is inversely proportional to the frequency of supply.
Induction motors turn at a speed proportional to frequency, so a high-frequency power supply allows more power to be obtained for the same motor volume and mass.
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| One of the first 400 Hz constant speed drives developed for aviation |
Drawback of operating at The Higher Frequency
The constant or core losses, like a hysteresis loss & Eddy current loss increases. Because of these losses are directly proportional to the frequency.
The inductive reactance increases.Reactive drops are caused by the inductive properties of the conducting cables. This type of loss is affected both by the length of the conductor as well as the frequency of the power flowing through it. As frequency increases, the larger the voltage drop becomes.
Due To These drawbacks limit the application of high frequency in power systems. But in aircrafts these are not major.
That Why We Use Electric Supply to houses is 230V, 50Hz / 110V, 60Hz
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