working principle:
First, the signal of the transmitter or the instrument is modulated by the semiconductor device, and then is isolated and converted by the light-sensing or magnetic-inductance device, and then demodulated and converted back to the original signal before isolation, and at the same time, the power supply of the isolated signal is isolated. . Ensure absolute independence between transformed signals, power supply, and ground.
Features:
One: Protect the lower-level control loop.
Second: Weaken the impact of environmental noise on the test circuit.
Three: Suppress the interference of common ground, frequency converter, solenoid valve and unknown pulse to the equipment; meanwhile, it has the function of limiting pressure and flow for lower-level equipment. It is the transmitter, meter, frequency converter, solenoid valve PLC/DCS input and output, and communication. The loyal protection of the interface. Standard series rail structure, easy to install, and effective isolation: input, output and potential between power supply and earth. Can overcome the inverter noise and various high and low frequency pulsation interference.
What are the main types of signal isolator?
1) Isolator: In order to increase the load capacity of the instrument and ensure that the instruments connected to the same signal do not interfere with each other in industrial production, the electrical safety performance is improved. Need to input the voltage, current or frequency, resistance and other signals to collect, amplify, calculate, and anti-jamming processing, and then output the isolated current and voltage signals, safe to send to the secondary instrument or plc \ dcs use.
2) Distribution: The industrial site generally needs to adopt the two-wire transmission method. It is necessary to provide 24V power distribution for the primary instrument such as the transmitter, and at the same time, it must collect, amplify, calculate, and perform anti-interference on the input current signal. After processing, the isolated current and voltage signals are output for use by subsequent secondary meters or other meters.
3) Safety Barriers: Some special industrial sites (such as gas companies and chemical plants) not only require two-wire transmission, but also provide power distribution and signal isolation functions. They also need to have safety explosion-proof performance to reliably contain power. Power, prevention of ignition between power supply, signal and ground, current limiting, voltage limiting, double signal limiting and power supply loops limit energy entering hazardous locations within safe limits.
Signal isolators installation and maintenance should pay attention to what matters?
Due to different manufacturers, the production process and wiring definition of the isolator are not all the same, but the use situation is basically the same, so the protection requirements and maintenance of the product are basically the same.
1. Read the instructions carefully before use.
2. When used as signal isolation, the input should be cascaded into the loop circuit and the output connected to the sampling loop.
3. When used as isolated power distribution, the input should be incorporated into the power circuit and the output terminated.
4. If it is not working properly, check whether the wiring is correct and pay attention to the presence or absence of polarity and polarity.
Why is the signal received by the PLC sometimes inaccurate and with poor stability?
There are many reasons for this phenomenon. The potential difference between signal reference points of different instruments is an important factor. Because of this "poor" caused interference current between the instrument signal, resulting in PLC error and poor stability. Therefore, there is a common reference point for the signals of different equipment and instruments. The isolator completely isolates the inputs/outputs electrically and forms a common reference point in the PLC analog interface board. This solves the problem of achieving an ideal condition.
Is the 4-20mA channel isolated and there is no room for power in the cabinet?
A passive signal isolator, which can achieve 4-20mA signal isolation and no external power supply. PH1033 is such a product. Now that there are so many brands of isolators on the market, prices vary. How can we choose? The isolator is located between two system channels, so the first choice of isolator must be to determine the input and output functions, and to make the isolator input and output modes (voltage type, current type, loop-powered type, etc.) adapt to the front and rear channel interface modes. In addition, there are many important parameters such as accuracy, power consumption, noise, dielectric strength, and bus communication function that relate to product performance. For example, noise is related to accuracy, power consumption is related to reliability, and these require careful selection by the user. In short, the main principles for selecting isolators are their suitability, reliability, and cost-effectiveness.
The on-site two-wire pressure transmitter signal received by DCS is not stable. How to solve it?
The two-wire transmitter is used frequently in the industrial automation field and is the same as other industrial field devices. The two-wire transmitter also suffers from interference and interference. According to DCS analog board interface mode (current or loop power supply type), the isolation distributors with different functions are selected. In principle, it is required to provide the transmitter with isolated power and ensure that each transmitter has an independent power supply. The transmitter signal is isolated to the DCS. PLC analog board interface is a two-wire loop power supply, and the need for signal isolation, how to choose the product? The second-line loop power supply is a common analog interface. The product that fits this interface is called a two-wire loop isolation product. The isolating devices inside the isolation transmitter are all transformers. On the one hand, the signals are transmitted. On the other hand, the power at the power supply side is also transmitted to the input section, so that the various circuits of the input section can work normally. Examples PH2217 distribution products. There are several commonly used two-wire distributor? Commonly used two-wire isolation distributors have two series of varieties to choose from. The common point of the two series products is that they can provide an independent isolated power supply to the two-wire transmitter through isolation from the external power supply; the power distribution of the transmitter depends on the PLC and DCS analog input on site.
First, the signal of the transmitter or the instrument is modulated by the semiconductor device, and then is isolated and converted by the light-sensing or magnetic-inductance device, and then demodulated and converted back to the original signal before isolation, and at the same time, the power supply of the isolated signal is isolated. . Ensure absolute independence between transformed signals, power supply, and ground.
Features:
One: Protect the lower-level control loop.
Second: Weaken the impact of environmental noise on the test circuit.
Three: Suppress the interference of common ground, frequency converter, solenoid valve and unknown pulse to the equipment; meanwhile, it has the function of limiting pressure and flow for lower-level equipment. It is the transmitter, meter, frequency converter, solenoid valve PLC/DCS input and output, and communication. The loyal protection of the interface. Standard series rail structure, easy to install, and effective isolation: input, output and potential between power supply and earth. Can overcome the inverter noise and various high and low frequency pulsation interference.
What are the main types of signal isolator?
1) Isolator: In order to increase the load capacity of the instrument and ensure that the instruments connected to the same signal do not interfere with each other in industrial production, the electrical safety performance is improved. Need to input the voltage, current or frequency, resistance and other signals to collect, amplify, calculate, and anti-jamming processing, and then output the isolated current and voltage signals, safe to send to the secondary instrument or plc \ dcs use.
2) Distribution: The industrial site generally needs to adopt the two-wire transmission method. It is necessary to provide 24V power distribution for the primary instrument such as the transmitter, and at the same time, it must collect, amplify, calculate, and perform anti-interference on the input current signal. After processing, the isolated current and voltage signals are output for use by subsequent secondary meters or other meters.
3) Safety Barriers: Some special industrial sites (such as gas companies and chemical plants) not only require two-wire transmission, but also provide power distribution and signal isolation functions. They also need to have safety explosion-proof performance to reliably contain power. Power, prevention of ignition between power supply, signal and ground, current limiting, voltage limiting, double signal limiting and power supply loops limit energy entering hazardous locations within safe limits.
Signal isolators installation and maintenance should pay attention to what matters?
Due to different manufacturers, the production process and wiring definition of the isolator are not all the same, but the use situation is basically the same, so the protection requirements and maintenance of the product are basically the same.
1. Read the instructions carefully before use.
2. When used as signal isolation, the input should be cascaded into the loop circuit and the output connected to the sampling loop.
3. When used as isolated power distribution, the input should be incorporated into the power circuit and the output terminated.
4. If it is not working properly, check whether the wiring is correct and pay attention to the presence or absence of polarity and polarity.
Why is the signal received by the PLC sometimes inaccurate and with poor stability?
There are many reasons for this phenomenon. The potential difference between signal reference points of different instruments is an important factor. Because of this "poor" caused interference current between the instrument signal, resulting in PLC error and poor stability. Therefore, there is a common reference point for the signals of different equipment and instruments. The isolator completely isolates the inputs/outputs electrically and forms a common reference point in the PLC analog interface board. This solves the problem of achieving an ideal condition.
Is the 4-20mA channel isolated and there is no room for power in the cabinet?
A passive signal isolator, which can achieve 4-20mA signal isolation and no external power supply. PH1033 is such a product. Now that there are so many brands of isolators on the market, prices vary. How can we choose? The isolator is located between two system channels, so the first choice of isolator must be to determine the input and output functions, and to make the isolator input and output modes (voltage type, current type, loop-powered type, etc.) adapt to the front and rear channel interface modes. In addition, there are many important parameters such as accuracy, power consumption, noise, dielectric strength, and bus communication function that relate to product performance. For example, noise is related to accuracy, power consumption is related to reliability, and these require careful selection by the user. In short, the main principles for selecting isolators are their suitability, reliability, and cost-effectiveness.
The on-site two-wire pressure transmitter signal received by DCS is not stable. How to solve it?
The two-wire transmitter is used frequently in the industrial automation field and is the same as other industrial field devices. The two-wire transmitter also suffers from interference and interference. According to DCS analog board interface mode (current or loop power supply type), the isolation distributors with different functions are selected. In principle, it is required to provide the transmitter with isolated power and ensure that each transmitter has an independent power supply. The transmitter signal is isolated to the DCS. PLC analog board interface is a two-wire loop power supply, and the need for signal isolation, how to choose the product? The second-line loop power supply is a common analog interface. The product that fits this interface is called a two-wire loop isolation product. The isolating devices inside the isolation transmitter are all transformers. On the one hand, the signals are transmitted. On the other hand, the power at the power supply side is also transmitted to the input section, so that the various circuits of the input section can work normally. Examples PH2217 distribution products. There are several commonly used two-wire distributor? Commonly used two-wire isolation distributors have two series of varieties to choose from. The common point of the two series products is that they can provide an independent isolated power supply to the two-wire transmitter through isolation from the external power supply; the power distribution of the transmitter depends on the PLC and DCS analog input on site.
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