What's the use of isolating the safety barrier? What are the characteristics?


Release time:

2022-05-09

What's the use of isolating the safety barrier? What are the characteristics? Circuit energy-limiting related equipment that limits the electrical energy of a circuit to achieve an intrinsically safe explosion-proof function is commonly referred to as an isolation barrier. So, what's the use of isolating the safety barrier? What are the characteristics?

What's the use of isolating the safety barrier? What are the characteristics?

隔离安全栅

Circuit energy-limiting related equipment that limits the electrical energy of a circuit to achieve an intrinsically safe explosion-proof function is commonly referred to as an isolation barrier. So, what's the use of isolating the safety barrier? What are the characteristics?

The role of 1. isolation barrier

The isolation barrier usually consists of three parts: the loop energy limiting unit, the current isolation unit and the signal processing unit. The core circuit of the loop energy limiting unit is the basic energy limiting circuit of the isolation barrier. In addition, there are auxiliary circuits to drive the field instrument power circuit and instrument signal acquisition detection circuit. The galvanic isolation unit comprises a transformer isolation element, a mode-to-frequency conversion and a frequency-to-mode conversion circuit. The signal processing unit performs signal processing according to the functional requirements of various isolation barriers. Therefore, in general, the function of the isolation barrier mainly includes circuit energy limitation, current isolation and signal processing.

Characteristics of 2. isolation barrier

There are two kinds of isolation barriers, one is Zener isolation barrier, and the other is isolated isolation barrier. The isolation barrier is more expensive than the Zener gate, but it has more advantages and features.

1. The isolation barrier can effectively isolate the field circuit in the dangerous area from the control system in the safe area of the main control room. This isolation can bring three benefits at the same time: First, the isolation barrier does not require intrinsically safe grounding. Simplifies engineering construction for intrinsically safe explosion-proof applications. Secondly, the anti-interference ability of the detection and control loop is greatly enhanced. Third, allow the field instrument to be grounded, and the field instrument grounding will not interact with the control system grounding.

The application of the isolation barrier can shorten the preparation time for driving and reduce the parking time. This is because the self-protection ability of the isolation barrier is much stronger than that of the Zener barrier, and the possibility of accidental damage is small. At the same time, the isolation fence allows live maintenance of field instruments and reduces parking.

3. The isolation barrier has a powerful signal processing function, which provides more choices for the application of field instruments and control systems, so that the configuration of the entire system is more effective and reasonable.

4. When the user applies DCS and ESD at the same time, choose an isolation barrier with one entrance and two exits, which can effectively isolate the two systems and avoid the failure of one system affecting the normal operation of the other system.

When selecting a suitable isolation barrier, pay attention to the following aspects when using it.

First of all, pay attention to the capacitive and inductive reactance of cables and field devices. Explosion-proof is the explosion-proof system. In addition to the explosion-proof rating required for the isolation barrier, the energy storage of cables and field devices is also a key issue. Especially after parameter certification replaces system certification, engineers should pay special attention to this problem.

Second, pay attention to grounding gas. Zener isolation barrier needs to be grounded, and the grounding resistance should be less than 1.

Third, cables and non-cables should be laid separately in different trunking. and should be clearly marked.

Fourth, pay attention to power failure when replacing.