What is Alternating Current??

Can you imagine your life without electricity? If there is no electricity there will be no progress in our lives. In this tutorial we will learn about what is an alternating current ?Let us first learn how and when electric current came into existence.

电力不是发明的，它以能量的形式存在于性质中。关于电力进行了许多实验。本杰明·富兰克林危险风筝实验证明了闪电是电。尼古拉·特斯拉（Nikola Tesla）和托马斯·爱迪生（Thomas Edison）发明了A.C. Current和D.C.电流。这些科学家就当前符号的标准化进行了斗争。从最后，交替的电流赢得了战斗并成立。

这种交替的电流是由著名的科学家“尼古拉斯·特斯拉（Nicholas Tesla）”发明的，指出了托马斯·阿尔瓦·爱迪生（Thomas Alva Edison）的DC Power Houses的效率低下之后。

What is Alternating Current??

The current, which reverses its direction periodically in second , is called “Alternating Current”.The polarity of the voltage , is reversed periodically in an Alternating Current source. So the current reverses its direction periodically. Hence the name Alternating Current (AC) indicating current is alternating (periodically).

该电流在一秒钟内改变其方向的次数可以定义为交替电流的频率。50Hz频率意味着它在一秒钟内将其变化50次。

在此电流中，带电的粒子在方向上从零移动到最大值，跌至零，并在相反的方向上以相同的值（为负）移动另一个周期。在所有情况下，AC电流在两个方向上处理的值均相等。

它具有大小，方向，并且随时间而变化。AC将以正方向和负方向流动，因此是双向的。一般来说AC waveformis represented by Sinusoidal waveform and its mathematical formula is

A (t) = A sin (2πƒt)

Where ,

一个是信号的大小

t is the time period

f is the frequency of signal

Generation of Alternating Current

Alternating current generating devices are called Alternators. The alternating current can be generated by many methods and by using many circuits. The simplest method of generating AC current is ‘Using Basic Single Coil AC Generator’.

Working principle

An AC generator works depending upon the principle of Faraday’s electromagnetic induction to convert mechanical energy (such as rotation) into electrical energy.

Construction

A simple generator consists of two permanent magnets. They will produce a fixed magnetic field between north & south poles. In this magnetic field, there will be a single rectangular loop of wire which is an important part of the alternator.

它将围绕由极磁体产生的磁场中的固定轴旋转，并切割磁通量。中央轴垂直于两个极点产生的磁场。

Process of Alternating Current Generation

• 一开始，电线是平行到田间，不切断磁通量，即磁力线。所以有没有电压induced in the loop.
• As the wire rotates in a counter-clockwise direction, the wire sides will cut the magnetic lines of force in opposite directions.
• 在任何时间瞬间，循环中的诱导电动势与电线环的旋转角度成正比。
• When the wire loop has rotated for 180^o在相反方向上的力线上，然后在相反方向的电线中进行电子。
• This means, for every complete revolution (360^o）电线，产生一个完整的正弦波形。
• 磁场中的旋转线始终与碳刷和滑动环连接。
• 这些用于转移线圈中诱导的电流。
• The amount of EMF induced in a coil is determined by its speed, strength, and length.
• We know that ‘frequency’ is Number of cycles per second.
• 产生的周期数将取决于旋转线的速度。这意味着线圈的速度越多，频率就越多。这意味着f与n直接成正比，其中“ n”电线旋转数量。
• The periodic reversal of polarity results in the generation of a voltage that has alternating polarity and hence the alternating current.

AC Wave Form

The alternating current can be represented by a waveform, with its amplitude and time period. There are many wave forms with which we can represent the AC current like square wave or triangular wave, but the easiest is to represent it with a sine wave.

对于正弦波的每个完整周期，我们看到正半周期和负半周期。这些正和负半周期将表示AC电流会定期改变其方向。我们将在其他会议上讨论正弦波的所有属性。

Mains (line) supply

提供给家庭的通用电力称为电力电力。此供应中的电流交替流动。从变压器电源线（向上或向下）连接到国内电源线的电源称为“主供应或线路供应”。我们在印度为家庭目的使用的主要供应量为220-240伏，频率为50Hz，而在美国（美国），它的频率为120伏，频率为60Hz。电气设备的制造商将根据电源供应设计其产品，以便它适用于所需的电压和频率范围。

AC比DC的优点

• 如果我们考虑产生AC和DC电流的成本，那么AC当前一代的成本比DC当前一代便宜。
• 使用交替电流的机器设计很简单，与使用直流电流的机器相比，它们的维护也很容易。
• 我们可以将交流电流用于长距离传输，但不能使用DC，因为交流电流的电压范围很高。
• AC current can be easily transformed from low to high voltage or high to low voltage by using a transformer. Hence the range of voltages in AC current is very wide.
• Without any loss we can convert the AC current to DC by using rectifiers and we can limit the magnitude of AC current with the help of an inductor or conductor at a very considerable loss.
• Long distance transmission losses in AC current are very less compared to DC transmission, when the supplied voltage is high.
• AC motors will produce a higher output (higher torque) than DC motors.

缺点

• The peak value of AC current is high, so it is very dangerous to use without insulation.
• 与直流传输相比，交流传输成本非常高。
• It a gives repelling shock of high voltage to a person who touches it and can cause electrocution.
• 有可能干扰通信信号。
• Applications of AC current
• All the electrical appliances we use in our day to day life work with AC current supply only. Ex: T.V., refrigerator, bulb, fan, Air conditioner etc.
• Alternating current is used in equipments where high power signals are transmitted. We use the Alternating Current in high power distribution systems like Antenna wave propagation, radio waves and ultrasonic wave propagation.
• 我们还使用变压器中的交流电流进行长距离传输，以提供许多其他目的。
• 我们主要使用电源需求高的行业中的电流类型。