What are the functions for isolators ?

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What are the functions for isolators ?

Postby maryzhu » Fri Apr 07, 2017 7:10 am

In recent days, as an electronic engineer in isolators [url removed, stealth advertusug detected - admin], I am going to make a project related to isolators. Today I come to this forum to turn to you to discuss my understandings are appropriate.

Here are my personal understandings:

The electronic project for isolators begins now:

In the industrial production process to achieve monitoring and control need to use a variety of automated instruments, control systems and executive machines
Structure, the signal transmission between them both weak to millivolt-level, micro-level small signal, there are dozens of volts, or even thousands of volts, hundreds of amps of large signals; both low-frequency DC signal, there are high-frequency Pulse signals, etc., constitute the system often found in the instrument and equipment between the signal transmission interfere with each other, resulting in system instability or even misuse. In addition to this situation in addition to each instrument, the performance of the equipment itself, such as the impact of anti-electromagnetic interference, there is a very important factor is due to instrument and equipment between the signal reference point there is a potential difference between, thus forming a " "Caused by the signal transmission process distortion. Therefore, to ensure the stability and reliable operation of the system, "ground loop" problem is in the system signal processing must solve the problem.

[image removed, stealth advertising detected-- admin]

Solve the "ground loop" approach

According to theoretical and practical analysis, there are three solutions:

The first option: all field devices are not grounded, so that all process loops have only one ground point, can not form a loop, this approach seems simple, but in practice is often difficult to achieve, because some equipment requirements must be grounded To ensure the accuracy of measurement or to ensure personal safety, some equipment may be due to long-term corrosion and wear or climate impact after the formation of a new grounding point.

The second option: the two points of the same potential, but because the grounding point of the resistance by geological conditions and climate change and many other factors, this program can not be done in practice.

The third solution: the use of signal isolation method in each process loop, disconnect the process loop, without affecting the normal transmission of the process signal, thus completely solve the problem of ground loops.

Isolator common power supply mode has independent power supply, loop power supply and output circuit power supply.

Separate power supply isolators:


Need to be equipped with independent 20 ~ 35VDC DC power supply. The advantages of this approach is the isolation of high precision transmission; power, input and output completely isolated, multi-system power supply without isolation, to ensure high anti-jamming performance, the input signal can be converted to other types of models.

Loop-powered isolators:

In the actual industrial monitoring system, DCS, PLC or other display instrument with the use of internal power supply more and more widely. Circuit-powered isolators are often unable to meet these card pieces on the signal isolation transmission accuracy requirements and high-speed transmission system voltage requirements of the conditions. Therefore, the output loop-powered isolator retains the superior performance of the independent power supply isolator and meets the requirements of the output circuit power supply interface.

Ps: Excuse me if I was wrong in words or expressions as I am a green hand in the field of isolators. I need continual learnings:

What is your idea ? Do you agree with my ideas ? Any of your ideas would be highly appreciated.

May someone would like to help ?

thanks in advance.
maryzhu
 
Posts: 6
Joined: Fri Mar 03, 2017 2:09 am

Re: What are the functions for isolators ?

Postby joeroot » Fri Jun 09, 2017 12:01 pm

Need to be equipped with independent 20 ~ 35VDC DC power supply. The advantages of this approach is the isolation of high precision transmission; power, input and output completely isolated, multi-system power supply without isolation, to ensure high anti-jamming performance, the input signal can be converted to other types of models.
joeroot
 
Posts: 1
Joined: Fri Jun 09, 2017 11:59 am


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