Why alternating current is use for electrical system?
Alternating current (AC) is the type of electric current generated by the vast majority of power plants and used by most power distribution systems.Alternating current is cheaper to generate and has fewer energy losses than direct current when transmitting electricity over long distances. Although for very long distances (more than 1000 km), direct current can often be better.
What is the difference between alternating current and direct current?
Recommended Reading
- What is Electricity
- What is a Circuit?
- Voltage, Current, Resistance, and Ohm's Law
- Electric Power
Why do we use alternating current for mains electricity?
- wye (Y) - wye (Y) is used for small current and high voltage.
- Delta (Δ) - Delta (Δ) is used for large currents and low voltages.
- Delta (Δ) - wye (Y) is used for step-up transformers i.e., at generating stations.
- wye (Y) - Delta (Δ) is used for step-down transformers i.e., at the end of the transmission.
What devices use alternating current?
Devices such as televisions, stereos, and videos use these alternating currents by turning them to the right flux. The Effect Of Alternating Current On The Body A current of 50 or 60 Hz passing through the body may cause a heartbeat, involving involuntary muscles.
What is meant by alternating current electricity?
Definition: Alternating Current (AC) is a type of electrical current, in which the direction of the flow of electrons switches back and forth at regular intervals or cycles. Current flowing in power lines and normal household electricity that comes from a wall outlet is alternating current.
What is DC and AC current difference?
Electric current flows in two ways as an alternating current (AC) or direct current (DC). In alternating current, the current keeps switching directions periodically – forward and backward. While in the direct current it flows in a single direction steadily.
Why AC current is used in homes?
The main factor that went into the choice of AC over DC was that AC is more efficient. Its ability to travel back and forth made gave it the ability to travel over longer distances. Thus making it able to power more homes.
What is alternating current and how does it work?
Alternating current (AC) is an electric current that periodically reverses its direction, in contrast to direct current (DC) which only flows in a single direction which cannot change sporadically.
Is house electricity AC or DC?
AC - Alternating CurrentWhen you plug things into the outlet in your house, you don't get DC. Household outlets are AC - Alternating Current. This current has a frequency of 60 Hz and would look something like this (if you plotted current as a function of time).
Are batteries AC or DC?
DCBatteries provide DC, which is generated from a chemical reaction inside of the battery.
Does a TV use AC or DC?
For electronics, like TV, laptop, whatever, you will always need DC, and significantly lower than 160V/315V (rectified AC).
What devices use AC current?
AC is also the more popular current when it comes to powering electric motors, a device that converts electric energy into mechanical energy. Some household appliances that we use that rely on this are, but aren't limited to: refrigerators, dishwashers, garbage disposals, and toasters.
Which is safer AC or DC?
Alternating current (A.C) is five times more dangerous than Direct current (D.C). The frequency of the alternating current is the main reason for this severe effect on the human body. The frequency of 60 cycles is in an extremely harmful range. At this frequency, even a small voltage of 25 volts can kill a person.
Why is AC current better than DC?
Alternating current is cheaper to generate and has fewer energy losses than direct current when transmitting electricity over long distances. Although for very long distances (more than 1000 km), direct current can often be better.
What produces AC current?
An alternating current is produced by an electric generator. An electric generator consists of a magnet and a loop of wire which rotates in the magnetic field of the magnet.
What is an example of an AC power source?
An ac is produced by an alternating emf, which is generated in a power plant, as described in Induced Electric Fields. If the ac source varies periodically, particularly sinusoidally, the circuit is known as an ac circuit. Examples include the commercial and residential power that serves so many of our needs.
Define the period of alternating current.
The period of Alternating current is the time taken by it to complete one cycle.
Define the frequency of the alternating current.
The frequency of AC is the number of cycles completed by the alternating current in one second.
Give one method of generating sinusoidal alternating current.
A sinusoidal AC can be generated by rotating a coil in a uniform magnetic field at a constant rate.
What is the RMS value of an AC?
The RMS value of an AC is the square root of the mean of the squares of the instantaneous values taken over a complete cycle.
What are the advantages of AC over DC current?
Alternating current can be stepped up or stepped down using a transformer. Using electronic supply units, AC can be converted into DC. Alternatin...
Define period of alternating current.
Period of alternating is the time taken by it to complete one cycle.
Define frequency of an alternating current.
The frequency of AC is the number of cycles completed by the AC in one second.
What is the mean value of an AC?
Mean value of AC is the mean or average of the instantaneous values of AC taken over half a cycle.
Curriculum
- Most students of electricity begin their study with what is known as direct current (DC), which is electricity flowing in a constant direction, and/or possessing a voltage with constant polarity. DC is the kind of electricity made by a battery (with definite positive and negative terminals), or the k…
Other uses
- Whereas the familiar battery symbol is used as a generic symbol for any DC voltage source, the circle with the wavy line inside is the generic symbol for any AC voltage source.
Purpose
- One might wonder why anyone would bother with such a thing as AC. It is true that in some cases AC holds no practical advantage over DC. In applications where electricity is used to dissipate energy in the form of heat, the polarity or direction of current is irrelevant, so long as there is enough voltage and current to the load to produce the desired heat (power dissipation). Howeve…
Operation
- Notice how the polarity of the voltage across the wire coils reverses as the opposite poles of the rotating magnet pass by. Connected to a load, this reversing voltage polarity will create a reversing current direction in the circuit. The faster the alternators shaft is turned, the faster the magnet will spin, resulting in an alternating voltage and current that switches directions more of…
Construction
- While DC generators work on the same general principle of electromagnetic induction, their construction is not as simple as their AC counterparts. With a DC generator, the coil of wire is mounted in the shaft where the magnet is on the AC alternator, and electrical connections are made to this spinning coil via stationary carbon brushes contacting copper strips on the rotatin…
Safety
- The problems involved with making and breaking electrical contact with a moving coil should be obvious (sparking and heat), especially if the shaft of the generator is revolving at high speed. If the atmosphere surrounding the machine contains flammable or explosive vapors, the practical problems of spark-producing brush contacts are even greater. An AC generator (alternator) doe…
Benefits
- The benefits of AC over DC with regard to generator design are also reflected in electric motors. While DC motors require the use of brushes to make electrical contact with moving coils of wire, AC motors do not. In fact, AC and DC motor designs are very similar to their generator counterparts (identical for the sake of this tutorial), the AC motor being dependent upon the reve…
Quotes
- So we know that AC generators and AC motors tend to be simpler than DC generators and DC motors. This relative simplicity translates into greater reliability and lower manufacturing cost. But what else is AC good for? Surely there must be more to it than design details of generators and motors! Indeed there is. There is an effect of electromagnetism known as mutual induction, whe…
Significance
- The fundamental significance of a transformer is its ability to step voltage up or down from the powered coil to the unpowered coil. The AC voltage induced in the unpowered (secondary) coil is equal to the AC voltage across the powered (primary) coil multiplied by the ratio of secondary coil turns to primary coil turns. If the secondary coil is powering a load, the current through the seco…
Example
- If the winding ratio is reversed so that the primary coil has less turns than the secondary coil, the transformer steps up the voltage from the source level to a higher level at the load: Figure below
Advantages
- The transformers ability to step AC voltage up or down with ease gives AC an advantage unmatched by DC in the realm of power distribution in figure below. When transmitting electrical power over long distances, it is far more efficient to do so with stepped-up voltages and stepped-down currents (smaller-diameter wire with less resistive power losses), then step the voltage ba…
Overview
Alternating current (AC) is an electric current which periodically reverses direction and changes its magnitude continuously with time in contrast to direct current (DC) which flows only in one direction. Alternating current is the form in which electric power is delivered to businesses and residences, and it is the form of electrical energy that consumers typically use when they plug kitchen applian…
History
The first alternator to produce alternating current was a dynamo electric generator based on Michael Faraday's principles constructed by the French instrument maker Hippolyte Pixii in 1832. Pixii later added a commutator to his device to produce the (then) more commonly used direct current. The earliest recorded practical application of alternating current is by Guillaume Duchenne, …
Transmission, distribution, and domestic power supply
Electrical energy is distributed as alternating current because AC voltage may be increased or decreased with a transformer. This allows the power to be transmitted through power lines efficiently at high voltage, which reduces the energy lost as heat due to resistance of the wire, and transformed to a lower, safer, voltage for use. Use of a higher voltage leads to significantly more effici…
AC power supply frequencies
The frequency of the electrical system varies by country and sometimes within a country; most electric power is generated at either 50 or 60 Hertz. Some countries have a mixture of 50 Hz and 60 Hz supplies, notably electricity power transmission in Japan. A low frequency eases the design of electric motors, particularly for hoisting, crushing and rolling applications, and commutator-type traction motors for applications such as railways. However, low frequency also causes noticeabl…
Effects at high frequencies
A direct current flows uniformly throughout the cross-section of a uniform wire. An alternating current of any frequency is forced away from the wire's center, toward its outer surface. This is because the acceleration of an electric charge in an alternating current produces waves of electromagnetic radiation that cancel the propagation of electricity toward the center of materials with high conductivity. This phenomenon is called skin effect. At very high frequencies the curren…
Mathematics of AC voltages
Alternating currents are accompanied (or caused) by alternating voltages. An AC voltage v can be described mathematically as a function of time by the following equation:
,
where
Information transmission
Alternating current is used to transmit information, as in the cases of telephone and cable television. Information signals are carried over a wide range of AC frequencies. POTS telephone signals have a frequency of about 3 kHz, close to the baseband audio frequency. Cable television and other cable-transmitted information currents may alternate at frequencies of tens to thousands of megahertz. These frequencies are similar to the electromagnetic wave frequencies often used t…
See also
• AC power
• Electrical wiring
• Heavy-duty power plugs
• Hertz
• Mains power systems