3. HHISTORY OF ALTERNATING CURRENTISTORY OF ALTERNATING CURRENT
William Stanley, Jr. designed one of the
first practical devices to transfer AC
power efficiently between isolated
circuits.
The AC power system used today
developed rapidly after 1886, and
included contributions by Nikola Tesla
and Carl Wilhelm Siemens.
4. WHAT IS ALTERNATING CURRENT ?WHAT IS ALTERNATING CURRENT ?
• Alternating current electricity is the type of electricity commonly used
in homes and businesses throughout the world.
• AC electricity is created by an AC electric generator, which
determines the frequency.
• An AC waveform can be sinusoidal, square, or saw tooth-shaped.
Some AC waveforms are irregular or complicated.
6. AAdvantagesdvantages
• The single greatest advantage of alternating current is that AC current can
be transformed and DC current cannot be transformed.
• It can be controlled by a wide range of components eg.resistors, capacitors
and inductors.
• This allows high-voltage electrical power to be distributed with smaller wires
and lower amperage.
8. RMS VALUESRMS VALUES
• Since voltage and current are always changing we need some way of
averaging out their effect.
• We use R.M.S values (root-mean-square)
• The R.M.S values are the DC values which give the same average power
output
9.
10. ACAC in capacitorsin capacitors
In an AC circuit, the current can continue to flow, as the plates become alternately
charged positively and negatively
For both AC and DC circuits, the voltage across the resistor is related to the current by
V=I.R
A similar relationship exists for a capacitor:
11. RReactanceeactance
• Reactance is a measure of how a capacitor can limit alternating current.
• It is similar to resistance but differs in that it is dependent on the
frequency of the ac supply.
• It also depends on the size of the capacitor.
13. Ac In Inductors
.In an AC circuit, the current is always changing so the inductor is always
producing an opposing voltage so is always limiting the amount of current that
can flow
For both AC and DC circuits, the voltage across the resistor is related to the
current by V=IR
A similar relationship exists for an inductor
14. reactance
It measures how well an inductor can limit alternating current
It depends on the frequency of the ac supply.
It depends on the size of the inductor