Nonlinear elements are used in various types of electrical circuits. They play an important role, but their use requires appropriate preparation of the entire system. What are nonlinear elements of an electrical circuit and how do they differ from linear elements?
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What are nonlinear electrical circuit elements?
The term nonlinear elements of an electric circuit refers to those elements that do not satisfy the principle of proportionality concerning current and voltage. In other words, the current-voltage characteristic of these elements is not a straight line. The nonlinear relationship between current and voltage that is formed depends on many factors.
A characteristic feature of nonlinear elements of a given system is the lack of constant resistance. It changes, depending on the value of current and voltage in the circuit. This property means that nonlinear elements can behave differently, depending on the operating conditions.
Nonlinear elements, in the context of current-voltage characteristics, are not a straight line, but can take on very different shapes. Special electrical equipment or modular equipment is necessary to perform appropriate measurements.
Nonlinear elements in electrical equipment (examples)
Nonlinear elements are used in many electrical circuits. One example is the diode, which is found in many devices. It is responsible for passing current in a unidirectional manner, in the direction of conduction. In the reverse direction, however, it is basically completely blocked. The nonlinearity of the diode is related to the fact of unidirectional passage, because the current flowing in the direction of conduction suddenly increases until a certain threshold voltage is reached.
The second example of a nonlinear element is a transistor. This applies to both bipolar and unipolar models. Depending on the specifics of the system, they can function as switches or amplifiers. Analyzing the current-voltage characteristics, it can be seen that in the case of transistors, it is very complicated. It depends on factors such as: base voltage or gate voltage. In this case, nonlinearity results from too small a change in the control voltage and a change to a large current at the output.
A non-linear element in the circuit may also be a thyristor, a varistor, or act as a diac or triac.
The difference between linear and nonlinear elements of electrical circuits
When talking about the difference between linear and nonlinear elements in electrical circuits, it can be noted that the fundamental difference is related to the relationship between current and voltage.
Linear elements are those components of electrical systems that satisfy Ohm's law. In the case of linear elements, it is observed that voltage and current are characterized by proportionality. Therefore, creating a voltage characteristic (IV), a straight line is created. The relationship between voltage and current is linear, which means that an increase in one parameter value will always cause an equal increase in the other value. Therefore, the relationships can be described using linear differential equations. In relation to linear elements, the so-called superposition occurs, which in practice means that the generated responses to input signals in the system can be summed up.
In the case of nonlinear elements, the relationship between current and voltage is not observed, which results in the formation of a nonlinear function of the current-voltage characteristic. The formation of the function is influenced by many external factors, such as temperature or the level of current voltage. To describe the relationships, it is necessary to use nonlinear mathematical equations. Additionally, the law of superposition does not occur. In practice, this means that input signals cannot be summed. The changes are not proportional.
Application of nonlinear elements in electrical circuits
Nonlinear elements are present in industries such as electronics . In the form of diodes, they are used in computer power supplies and mobile device chargers. As transistors, they are used in microprocessors and audio amplifiers.
Nonlinear elements are also found in lighting regulators, they allow for engine control, and they are found in power strips where they act as overvoltage protection. They are elements used in digital clocks and as signal generators. They are also used in photocells or digital cameras.
Installation cables create an electrical circuit, but they are not nonlinear in themselves. However, if they are to operate in such systems, they must be properly matched so that the entire circuit functions correctly and without failure. Cables and wires must be able to carry pulse current and must be resistant to electromagnetic interference. Their role is to minimize voltage drops that could disrupt the operation of individual components. Circuits with at least one nonlinear element must be characterized by high resistance to surges and protection against overheating, regardless of the voltage source.
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