Introduction
In this article, we will explore the concept, working principle, advantages, disadvantages and role of signal isolators in various applications. Signal isolators are a particularly important electronic device that plays an indispensable role in modern industrial and electronic systems.
1
The Importance of Signal Isolation
Signal isolation plays a key role in industrial and electronic systems. It is mainly used to eliminate various interferences during operation. Whether it is the signal transmission of sensors and transmitters, or the signal transmission of data acquisition systems, PLCs and DCS systems,
signal isolation plays a vital role. By providing electrical isolation between two parts of the circuit, signal isolators effectively avoid signal interference. This is very important to ensure the stable operation of electronic equipment and prevent misoperation. The main functions are shown
in the following figure:
2
Basic Concepts of Signal Isolators
Signal isolators are special electronic devices that are used to separate or isolate one electrical signal from another in a control system. They provide electrical (galvanic) isolation between input and output circuits, which is very important in various industrial and engineering applications
to prevent interference and ensure safety. In addition, signal isolators can also be used to enhance and protect process signals, ensuring that signals from sensors and transmitters can be accurately and correctly transmitted to the control system. This protects sensitive control equipment
from voltage spikes, ground loops, and other electrical-related interference, while also ensuring the quality and integrity of the signal. The general wiring diagram is as follows:
3
Types of signal isolators
3.1
Resistor input isolators
Resistor input isolators are mainly used for measurements such as temperature, pressure, and strain. These measurements are usually converted into resistance values and then transmitted to the control system. In this process, resistor input signal isolators play an important role in maintaining signal accuracy and reducing noise. They provide a stable and reliable data transmission platform for various measurement devices.
3.2
Galvanic isolators
Galvanic isolators provide electrical isolation between input and output current signals. They maintain a specific current level proportional to the input current on the output side while isolating the two sides to prevent any unwanted interaction. This is very important to ensure accurate
transmission of current signals and prevent problems such as current leakage.
3.3
Millivolt isolators
Millivolt isolators are commonly used in various applications where accurate measurement and signal integrity are critical. These isolators can handle low-level voltage signals in the millivolt range and maintain separation between input and output circuits to prevent ground loops and
interference. This is extremely valuable for data acquisition and processing of precision instruments.
4
Types of Signal Isolators
4.1
Active Isolators
An active isolator is an electronic device that uses active components such as amplifiers, operational amplifiers, or other active circuits to provide isolation between two circuits. It includes a power supply for operation. Active isolators can actively manipulate the signal between input and
output, allowing signal conditioning, amplification, or inversion as needed. This makes active isolators widely used in a variety of complex electronic systems.
4.2
Passive Isolators
Passive isolators do not require an external power supply or power supply to operate. It relies entirely on passive electronic components such as resistors, capacitors, transformers, and optocouplers to provide isolation between two circuits. Although they do not actively amplify or
manipulate signals, they can still provide effective isolation for human-machine applications. This makes passive isolators important in applications where circuit safety and stability need to be guaranteed.
5
Advantages and Disadvantages of Signal Isolators
The main advantages of signal isolators include providing electrical isolation to prevent ground loops, reducing the risk of damage caused by voltage spikes or transients, maintaining signal integrity, ensuring accurate measurements, eliminating electromagnetic interference (EMI), and
improving safety in industrial applications.
However, due to the presence of isolation components, the signal may drop. This is an important factor that designers need to consider when using signal isolators.
6
Application of signal isolators
Signal isolators are widely used in process control in industrial environments to separate control circuits from measurement circuits, as well as safe electrical isolation in medical and chemical environments. In these occasions, signal isolators can not only improve the operating efficiency
and stability of equipment, but also effectively protect the safety of operators and equipment.
Summary
Signal isolators play a vital role in modern industrial and electronic systems. There are various types and types of signal isolators, including resistive input isolators, current or voltage isolators, millivolt isolators, as well as active isolators and passive isolators. These different isolators have
their own characteristics and advantages and are suitable for different application scenarios.
They ensure the accurate transmission of various signals in complex environments, while also providing effective electrical isolation to prevent interference and protect equipment. Although there are some problems that may cause signal drop, the advantages of signal isolators clearly
outweigh their disadvantages. Their application in industrial process control and even medical and chemical environments has been widely recognized.
