Introduction to Some Relevant Knowledge About Isolation Safety Barriers
发布时间：
2022-05-06
Introduction to Some Relevant Knowledge About Isolation Safety Barriers I. Application Advantages of Selecting Isolation Safety Barriers Compared with Zener safety barriers, isolation-type safety barriers, although more expensive, still offer numerous advantages and distinctive features. The same isolation-type safety barrier provides users with considerable convenience, leading an increasing number of users to favor this type. Safety barriers must be explosion-proof certified; the most common type is intrinsically safe.
Introduction to Some Relevant Knowledge About Isolation Safety Barriers
I. Application Advantages of Isolation Safety Barriers
Although isolation safety barriers are more expensive than Zener safety barriers, they still offer numerous advantages and distinctive features. The same type of isolation safety barrier provides users with significant convenience, which is why an increasing number of customers are opting for isolation safety barriers. Safety barriers must be explosion-proof certified; the most common type is intrinsically safe.
Characteristics and Fault-Handling Methods of Isolation Safety Barriers:
(1) Isolation safety barriers are used to permit grounding of field instruments and to allow field instruments to operate without isolation.
(2) Isolation safety barriers effectively isolate field-loop signals in hazardous areas from loop signals in safe areas. As a result, intrinsically safe automatic control systems no longer require an intrinsically safe grounding system, thereby simplifying the implementation of intrinsically safe explosion-proof systems.
(3) The use of isolation safety barriers significantly enhances the anti-interference capability of the detection and control loops, thereby improving system reliability.
(4) The isolation safety barrier features a large number of protective circuits, reducing the likelihood of accidental failure. It permits live maintenance of field instruments, thereby shortening project startup preparation time and minimizing downtime.
(5) When both DCS and ESD systems are deployed, selecting a safety barrier with one input and two outputs can effectively isolate the two systems and prevent mutual interference.
(6) Isolation safety barriers exhibit robust signal-processing capabilities, including digital input state control, mV-to-4–20 mA conversion for Pt100 sensors, and more. This enhances the convenience, rationality, and effectiveness of field instrumentation and control system applications.
(7) Loop-powered isolation safety barriers not only retain the advantages of active isolation safety barriers but also offer the same ease of wiring as Zener safety barriers, eliminating the need for a separate 24 V power supply. They are particularly well suited for DCS systems in which I/O cards are directly powered.
II. Troubleshooting Methods for Common Faults of Isolation Safety Barriers
1. The power indicator light is off, or the LCD screen is not displaying.
(1) Verify that the instrument’s power connection is correct and secure.
(2) Check whether the power supply voltage is normal.
(3) Check whether the positive and negative terminals of the 24V power supply are reversed.
2. No signal output.
(1) Has the input signal been correctly connected to the input terminal?
(2) Does the input signal type match the instrument’s input type?
(3) Are the output terminals securely fastened?
(4) Ensure that the detachable external terminals are fully seated.
(5) Open circuit in the external output circuit.
3. Large deviation in output values.
(1) Are the positive and negative leads of the thermocouple input connected in reverse?
(2) Verify that the three-wire connection is correct when connecting the resistance thermometer input.
(3) Is the polarity of the output wiring reversed?
(4) When outputting current, is the sum of the external load resistances greater than the specified resistance (for 4–20 mA output)?
(5) When the output voltage is applied, is the external load resistance less than 500 kΩ?
(6) Undervoltage of the power supply.
4. Unstable output signal.
(1) Check that the wiring is secure.
(2) Check whether the input signal is stable.
(3) Check that the output circuit wiring is secure.
(4) Check the surrounding environment of the instrument for any high-power electromagnetic equipment.
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