A transformer, or simply a "trafo," is a machine used in alternating current (AC) systems to convert voltage through magnetic induction. Transformers have no moving parts, and the transformation is carried out without changing the frequency.
Transformers are generally used in the transmission and distribution of energy. During the transmission of electricity from power plants to end users, voltage transformation and power loss occur in the lines. To minimize this loss, it is necessary to raise the voltage while keeping power constant. This means reducing the current. With transformers, intermediary stations can be set up before the energy reaches the end user, allowing the cross-sectional area of conductors to be reduced. This reduces losses and costs.
Transformers are typically used to raise or lower voltage or current in an electrical circuit. In electronics, they are also used to connect amplifiers in different circuits or to convert DC (direct current) waves into higher AC (alternating current) values. Additionally, transformers in electronics are used to transmit specific frequencies.
What Are the Characteristics of Transformers?
Transformers consist of a core and two coils. This structure transfers electrical energy from one conductor to another. Voltage is applied to one of these two coils on the core, generating a magnetic flux. This magnetic flux undergoes continuous changes in direction and intensity.
The magnetic flux induces voltage in the output coil. In summary, the voltage applied to both coils generates a magnetic field, which transfers energy to the other coil. If the output winding count in the transformer is higher than the input winding count, the output voltage will be greater than the input voltage.
Purposes of Using Transformers
Transformers can be used for multiple purposes and can be encountered in various fields. Generally, they are used for three different purposes:
To increase or decrease the existing voltage or current,
To protect multiple circuits with a common chassis connected to the same power line from short circuits,
To ensure impedance matching.
Where Are Transformers Used?
Transformers can be used wherever electricity is used. They are found in many places where electrical energy exists and are available in various types and sizes depending on the working environment. Transformers are used in the distribution of electrical energy, power plants, and devices that draw energy from the network. In short, if alternating current (AC) is used in a location, a transformer is present. Transformers are available in various types. Now that you know what a transformer is, its features, purposes, and usage areas, you can also learn about its types.
What Are the Types of Transformers?
Transformers are classified based on various criteria, including the number of phases, core type, working environment, and method of increasing or decreasing voltage.
The first transformer classification is based on the number of phases, divided into single-phase and multi-phase transformers:
Single-Phase: These transformers have a single input winding, but the output winding may vary.
Multi-Phase: These transformers have multiple input windings.
Another category is based on core type. Transformers are classified into three main types according to core type: core type, shell type, and distributed type.
Core Type: Core-type cores are used in high-power, high-voltage transformers because the insulation of windings is easier.
Shell Type: In shell-type cores, windings are wound on the central limb. Unlike core types, these are used in low-power, low-voltage transformers.
Distributed Type: These cores have a cross-shaped appearance. The windings are wrapped around the middle leg, resulting in minimal leakage flux, reducing idle working currents.
Transformers can also be classified according to their purpose, with five different transformer types as follows:
Auto Transformer: This type uses a single winding as both input and output, achieving high efficiency with a much smaller size compared to other types.
Measuring Transformer: This type is used for measurement purposes in environments with high current and voltage levels.
Step-Down Transformer: In this type, the output voltage is lower than the input voltage, reducing the electrical energy's voltage. This is one of the most commonly used transformers.
Step-Up Transformer: This type is the opposite of the step-down transformer. The output voltage in these transformers is higher than the input voltage.
Isolation Transformer: The purpose of this type of transformer is to electrically isolate two circuits.
The final type of transformer is categorized by its working environment, with various types available depending on the environment. Examples include underwaterr, underground, and indoor transformers.
How Do Transformers Work?
Transformers operate on a simple principle. An alternating current applied to the coil creates a time-varying magnetic flux on the magnetic core, inducing a voltage in the other coil. The ratio of turns between the primary and secondary windings determines the ratio of input to output voltage, providing upward or downward transformation of voltage.
When an appropriate AC voltage is applied to the primary winding, the current passing through it creates a magnetic field in the core, which completes its circuit on the limb where the secondary winding is wound. According to the induction principle, when subjected to a variable magnetic field, voltage is induced at the ends of the conductive coil. In this scenario, the voltage applied to the primary winding and the magnetic field generated on the limb of the secondary winding induce an electromotive force (EMF) on the secondary coil. This electromotive force is often abbreviated as EMF. Through these methods, voltage is induced on the secondary winding via induction, even though there is no electrical connection between the primary and secondary windings. Auto transformers differ slightly, as they have an electrical connection between the windings since both the input and output circuits are wound on the same core.
When an AC voltage is applied to the primary winding of transformers, a variable magnetic field is created. This magnetic field completes its circuit on the core, where the secondary winding is also located. The applied voltage to the primary winding continuously changes direction and intensity over time, resulting in constant changes in the magnetic field's direction and strength. The alternating field cutting through the secondary winding induces an AC voltage in the winding.
When a direct voltage is applied to the primary winding of transformers, a magnetic field is also generated, but it is static. Since the direction and intensity of this field do not change, no electromotive force (EMF) is induced in the secondary winding.
In transformers, to change and stabilize the voltage with the conversion ratio, the winding taps are taken out. The number of output taps is calculated according to the voltage adjustment range. A 5% voltage adjustment is sufficient for distribution transformers, while adjustments up to 20% may be possible for long-distance, high-power, high-voltage transformers. In transformers, voltage adjustment can be made continuously or in steps by changing the transformation ratio. Stepped voltage adjustments can be made on-load or off-load. For such adjustments, a specially designed tap-changer switch is used.
When adjusting voltage under load, care must be taken to prevent the disconnected winding taps from short-circuiting, as this would cut off power. A tertiary winding, parallel windings, a reactance coil, or resistors can be used for load adjustments.
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