The Technical Characteristics of Intrinsically Safe Barriers

Intrinsically Safe Barrier in Explosion-Proof Systems

Intrinsically Safe Barrier plays a crucial role in the design of intrinsically safe explosion-proof systems. It is installed in safe locations, containing intrinsically safe and non-intrinsically safe circuits. By restricting current and voltage through specific limiting circuits, it restricts the energy sent to the field intrinsically safe loop, preventing hazardous energy from entering the intrinsically safe circuit from the non-intrinsically safe circuit. The Intrinsically Safe Barrier is referred to as an associated apparatus in intrinsically safe explosion-proof systems.

Intrinsically Safe Barrier as a safety keeper, acts as the safety interface of the intrinsically safe loop. It can bidirectionally transmit electrical signals between the safe zone (non-intrinsically safe) and the hazardous zone (intrinsically safe), and can restrict the energy transfer from the safe zone to the hazardous zone due to a fault. Commonly Intrinsically Safe Barriers include Zener and isolating types. Because Intrinsically Safe Barriers are designed as an energy-limiting interface between field devices and control room equipment, they can ensure that the energy sent to the field devices through it is intrinsically safe, regardless of whether the control room equipment is operating normally or under fault conditions.

Installation and Debugging of Intrinsically Safe Barriers

When installing Intrinsically Safe Barriers, ensure that the environmental conditions meet the usage requirements. The wiring of the intrinsically safe and non-intrinsically safe circuits of the isolating safety barriers should be laid separately in wiring ducts and each should use its independent protective conduit. Other power lines, including those used for intrinsically safe circuits, are not allowed in the protective conduits of the intrinsically safe side. Wires leading to hazardous locations should use intrinsically safe wires marked in blue, and the cross-sectional area of the conductor should be greater than 0.5mm², with an insulation strength greater than 500V.

Before debugging the powered isolating safety barriers, it is crucial to verify that the model, wiring method, and circuit polarity of the isolating safety barriers conform to the design and product specifications. Failure to comply may result in harm to personnel and equipment. It is strictly forbidden to test the insulation strength between the terminals of the isolating safety barriers with a megohmmeter. If it is necessary to check the system's insulation strength, first disconnect all wiring to avoid blowing the quick-acting fuse inside the safety barrier.

Protective Functions of Intrinsically Safe Barriers

Intrinsically Safe Barriers are mainly composed of current limiting circuits, voltage limiting circuits, and quick-acting fuses. They have the following protective functions:

Overvoltage protection

When the input voltage on the safe side exceeds the normal operating voltage, the safety barrier will automatically cut off the input power supply, making the Intrinsically Safe Barrier remain in an off state. The output voltage and current to the hazardous side on site will be zero. After the input voltage returns to normal, the safety barrier will automatically resume operation.

Short-circuit protection

When a short circuit to ground occurs on the hazardous side, the output part of the safety barrier will automatically shut off, and the output voltage and current will be zero. After the short-circuit fault is cleared, the safety barrier will automatically resume operation.

Advantages of Intrinsically Safe Barriers

The advantages of isolating safety barriers

Although isolating safety barriers are more expensive, their benefits and features bring users great convenience, leading more and more users to choose isolating safety barriers.

Improving system reliability

Using isolating safety barriers can effectively isolate signals between the hazardous and safe zones, greatly enhancing the anti-interference ability of detection and control loops, and improving system reliability.

Simplifying construction

The use of isolating safety barriers eliminates the need for intrinsically safe grounding systems in intrinsically safe automated control systems, simplifying the construction process.

Field instrument grounding

Allowing field instruments to be grounded and the use of non-isolated field instruments.

Protective function circuit

Isolating safety barriers have various protective function circuits, reducing the likelihood of accidental damage, and allowing for live maintenance of field instruments, shortening project start-up preparation time, and reducing downtime.

Powerful signal processing capabilities

Isolating safety barriers have strong signal processing capabilities, such as controlling the input state of switch quantities, converting mV, Pt100 to 4～20mA, etc., providing greater convenience for the application of field instruments and control systems.

System isolation

When users simultaneously apply DCS and ESD, the selection of a dual-output Intrinsically Safe Barrier can effectively isolate the two systems, avoiding mutual interference between the systems.

Through these technical characteristics, the application of Intrinsically Safe Barriers in industrial automation and safety management can better ensure the safety of equipment and personnel, providing reliable explosion-proof solutions for various industries.