AC generators or alternating current generators. One of the coolest inventions of electrical engineering ever. Unlike the DC motors. It produces pulses of alternating current that we can use for different purposes.
A lot to learn about AC generators: luckily, we will be covering several different things in this article. If interested in learning about the AC generators, you keep reading.
Understanding the Overall Construction
To understand the concept of an AC generator and get familiar with it. We need to know about the construction and mechanism first. Without it, we won’t be able to learn about the AC generators a lot.
Magnets
Magnets are the two main components that make up the whole AC generator. Without magnetic poles, there would be no magnetic field. As a result, the generator won’t be able to produce the alternating current at all.
To learn more about why the magnets are a necessary part of any AC generator. We need to recall the faraday law of electromagnetic induction. It says that a current will induce in that conductor whenever a conductor is exposed to a magnetic field.
We need two magnetic poles around the Armature to ensure that the flux in the coil keeps changing. And as a result, the current will produce in the Armature.
Armature of the AC Generator
The Armature of the AC generator is its essential part. It consists of a rectangular coil of wire that lies between the two poles of magnets. The Armature can turn. The Armature ends connect to the slip rings, which are further in contact with the brushes.
Slip Rings of an AC Generator
After the Armature, the 2nd part of an AC generator is the slip rings. Each slip ring connects to the end of the Armature.
These rings’ purpose is to take the coil’s current-induced due to the magnetic flux change. The current then reaches the stationary part of the generator through the brushes.
Ac Generator Rotor and Stator
The stator and Rotor are the two crucial components that make up the whole AC generator. The stator is a stationary component, holding the armature winding. The main application of the armature winding is to act as a bridge for the current.
The current flows through the winding and reaches the load used for many different applications—the stator base on 3 other parts.
- Stator Frame
- Stator Core
- Armature Winding
The stator frame is the outer layer that holds the core and the armature winding. It can call the protective shell of the two parts.
Besides this, the stator core laminate with steel or iron. The reason behind the lamination is to reduce the eddy currents losses during the operation.
Apart from that, different slots hold the armature winding.
AC Generator Load
Finally, there is a load component attached to the AC generator. It can be anything that consumes the current produced in the generator. The load receives the wind from the Armature through the slip rings and brushes.
Different elements can connect to the AC generator as a load that draws the current. From the generator and consumes it for other applications. The most common type of example of an AC generator load can be a light bulb.
Types of AC Generator
Ac generators are available in different types. Each type has its own applications and configuration. For your convenience, we’ve divided the Ac generators into the following main types.
- Three- Phase generators
- Single- Phase generators
- synchronous generator
- induction generators
Single Phase generator
Single Phase Ac generators are the most common types. That produces an alternating current. Its voltage is usually around 120 to 230volts. And can use for several different applications. It uses two wires to distribute the electricity over the load.
One of the two wires carries the current, called the Phase wire or the live wire. In comparison, the other one is a neutral wire that completes the circuit and allows the current to flow through it.
The Single-phase generator can generate enough electrical energy to feed different small appliances. It can supply power to lights, heating appliances, and other stuff.
But, it would help if you kept in mind that they can not run heavy appliances. If you want to power, you will need a single-phase AC generator.
Three Phase Generator
A Three-phase Ac generator is a type of generator that produces 3 different energy phases. Having the same frequency and amplitude. The phase difference between them is usually kept around about 120 degrees to avoid interruption.
Ac generator can provide stable AC due to the single-phase. It uses for heavy appliances like Air conditions etc. You can run your entire home. Single-phase AC generators as they provide regular electricity.
You need to know about the three-phase AC generator is the division of power as the full capacity divides into 3 different phases. The load components use only 1/3rd part of the total energy.
So, you will need to add the load; otherwise, it can mess things up.
Synchronous Generator
Synchronous Generators are a particular type of Ac generator. That converts mechanical energy into electrical energy at a specific voltage and frequency. It always runs at a constant speed, which knows as the synchronous speed. Pls, click here to find out more!
The working principle of the synchronous generator is also based on the Faraday law of electromagnetic induction. In such generators, the magnets rotate at a constant speed. And the conducting Armature is stationary.
In this case, the flux changes, and as a result, an alternating current is induced. Their main applications include nuclear, thermal, and hydropower system for generating voltages.
Induction Generators
Induction Ac generators are also known as the asynchronous ac generators. They are quite the opposite of the synchronous Ac generators construction. It uses induction motors to produce electrical energy.
Unlike the synchronous generators run at a constant speed. The induction generator usually runs faster than the synchronous speed. Induction generators can work in mini-hydro powerplants, wind turbines, and similar systems.
You must know about the induction generators that they need excitation power from an external source. That external source can be either an electrical grid. Or a phase is correcting capacitor. So, they can’t start a de-energized distribution system.
That sums up the four different types of AC generators. After learning about each of these. we hope you will understand how they work and how they can be useful for a particular application type.
AC Generator Frequency
In Ac generator, the cycles of the Rotor are usually calculated. The number of cycles per second calls the frequency of the AC generator.
Usually, the United States AC generators run at 3600RPM and have 2 poles. After doing the math, we know that the output frequency will be 60Hz.
Generally, you can calculate the frequency of any Ac generator with the help of this formula.
N = 120*f/p
Here N is the synchronous speed, P is the number of poles used in the generator, and f is the frequency. Using this formula, you can calculate the Fre. of anyone.
Apart from that, if you already know about the generator’s frequency. You can calculate the synchronous speed. Likewise, if you know both values, you can learn about the number of a generator’s poles.
Controlling the Frequency of Ac Generator
As already discussed above, we can calculate the frequency of different ac generators. But, the question is, can we control the frequency of the ac generator?
The answer to the question is sure; we can control the frequency of the ac generator. As we already know that the frequency of the ac generator can calculate using two terms.
- Speed of the rotor
- Number of poles
Suppose we change the configuration and set it to a new setup. We can definitely control the ac generator’s frequency. For example, if we increase or decrease the speed of the Rotor, it will affect the frequency.
Likewise, suppose we increase or decrease the poles of an ac generator. In that case, it will also affect the frequency of the generator.
High-Frequency Vs. Low Frequency
After learning about the frequency of an ac generator, you must be thinking about it now. You may be asking whether the high-frequency generators are dangerous or low-frequency generators.
If that is the case, let’s discuss it a bit in detail to make it easy for you. As we already learned that the Ac generator operates with a specific frequency. By frequency, we mean producing a sinusoidal wave that crosses zero and crest to trough.
The higher the frequency, the higher will be the natural zero time. In contrast, the lower the frequency, the lower will be the natural zero period. This means if the generator’s frequency is around 50Hz, its wild zero time will be 100.
If a generator’s frequency is 100Hz, this means the natural zero periods will be 200. Usually, frequencies with lower natural zero time periods are dangerous. You can understand this concept better by considering the voltage of mobile communications or radio waves.
As you can see, they are also electromagnetic pulses. Still, since their frequency is usually higher, no effect on our bodies. For example, the signal of GPS satellite ion L1 carrier frequency is 1574.42MHz.
This frequency is a lot higher, which means it’s natural zero periods will be twice. So, any shock to our body even being in contact with satellites’ voltage.
Losses in AC Generators
According to{“type”:”block”,”srcClientIds”:[“1a0e94c5-28e0-48d2-b334-3858f02f7f1c”],”srcRootClientId”:””} ohm’s law, the current is proportional to the voltage. The resistance of the system remains constant. This means that every system has its own resistance.
This resistance attenuates the total electrical energy produced by the ac generator. Thus, whenever an ac generator design to send power too far away distances. It generates more than the required strength.
Some of the losses due to resistance and Loss will always occur as there is no perfect machine ever invented on the earth’s surface. Sometimes the resistance is due to heat, which dissipates an immense electrical power in the ac generators.
While some times the power loss occurs during the transmission of it. In each case, we need to take care of it and compensate for the value somehow. In the ac generator, the losses are due to several factors, including the following.
- Copper
- Hysteresis
- Eddy current
In copper, the losses are due to the resistance of the material. It depends on the quality of the copper and its natural limitation.
Apart from that, the Loss due to the hysteresis. Because of the molecules’ changing magnetic polarity. Due to this, heat generates, which dissipates power.
The third type of Loss is due to the eddy current. Eddy current is a particular type of wind produced. Inside the ac generators, and it opposes the ac generated power.
These losses cannot cut, as we already mentioned earlier. It is because we can’t make a machine that is 100% efficient. But, we can cut them to certain levels.
