Zener & Galvanic Barriers

Zener and galvanic barriers are two types of electrical protection devices used in hazardous or explosive environments to prevent the ignition of flammable gases, vapours, or dust.

These barriers are commonly employed in industrial settings such as oil refineries, chemical plants, and mining operations. Their primary function is to limit the electrical energy transferred to a hazardous area, ensuring that it remains below the level that could cause ignition.

To ensure the safety of equipment and personnel in hazardous environments, various industry standards and certifications have been established. Some of the most recognised standards include:

• ATEX: A European Union directive that sets the minimum safety requirements for equipment and protective systems intended for use in potentially explosive atmospheres.
• IECEx: An international certification scheme that ensures the safety of equipment used in explosive atmospheres.

Zener and galvanic barriers are designed to meet the stringent requirements of these standards. They effectively limit the energy transferred to the hazardous area, ensuring it remains below the level that could cause ignition.

Zener barriers achieve this by using Zener diodes to clamp the voltage and divert excess current to the ground in the event of a fault. On the other hand, galvanic barriers provide galvanic isolation between the safe area and the hazardous area, preventing the transfer of potentially dangerous electrical energy.

What Is a Zener Barrier and How Does It Work?

A Zener barrier employs a Zener diode, which is a special type of diode that conducts electricity in reverse bias when the voltage across it exceeds a specific value known as the Zener voltage.

By utilising the Zener effect, these barriers regulate the energy entering the hazardous area below the level that could cause ignition. Zener barriers are commonly used to protect intrinsically safe circuits and devices, such as sensors, transmitters, and switches.

What Is a Galvanic Barrier and How Does It Work?

Galvanic barriers play a vital role in protecting sensitive equipment and preventing potential ignition sources. These barriers, also known as isolation barriers, provide a critical layer of protection by ensuring electrical isolation between hazardous and non-hazardous areas.

Galvanic barriers achieve this isolation by utilising components like transformers or optocouplers, which transmit signals magnetically or optically without a direct electrical connection. This ensures that even if a fault occurs in the non-hazardous area, the hazardous area remains safe.

A common application of galvanic barriers is in intrinsically safe systems, where the energy levels are limited to prevent ignition even in the event of a fault.

Intrinsically Safe Galvanic Isolator

An intrinsically safe galvanic isolator is a specialised type of galvanic barrier designed to meet the stringent requirements of intrinsically safe circuits.

Here are some of the features of galvanic isolators that make them intrinsically safe:

• Energy Limitation: Galvanic isolators strictly limit the electrical energy that can be transferred to the hazardous area, ensuring it remains below the ignition threshold of flammable gases or vapours.
• Fault Tolerance: They are designed to withstand faults like short circuits or overvoltages without compromising safety.
• Compliance with Standards: They meet the requirements of recognised intrinsic safety standards like ATEX and IECEx.

Benefits of Intrinsically Safe Galvanic Isolators

• Enhanced Safety: Minimise the risk of explosions in hazardous areas.
• Simplified Installation: Often easier to install than other protection methods, as they don't require complex grounding arrangements.
• Increased Flexibility: Allows for the use of a wider range of equipment in hazardous areas, including non-intrinsically safe devices, by providing a safe interface.
• Cost-Effectiveness: Can be a cost-effective solution for ensuring safety in hazardous areas, especially when compared to other more complex solutions.

What Is the Difference Between Zener Barrier and Galvanic Barrier?

Both Zener barriers and galvanic barriers are used to protect electrical circuits in hazardous environments, but they achieve this through different mechanisms:

Zener Barriers

• Utilise Zener diodes to limit voltage and divert excess current to the ground, acting as a safety valve to prevent dangerous energy buildup.
• Require a reliable ground connection to function effectively.
• Typically used in applications with lower power requirements and simpler signal types.

Galvanic Barriers

• Provide complete electrical isolation between safe and hazardous areas, preventing any direct current flow between them.
• Employ transformers or optocouplers to transmit signals magnetically or optically, ensuring no direct electrical connection.
• Do not require a ground connection in the hazardous area, simplifying installation in certain environments.
• Often preferred for applications with higher power requirements or complex signal transmission needs.

Types of Zener and Galvanic Barriers

Zener and galvanic barriers come in various types to cater to different signal requirements and application needs in hazardous environments.

Types of Zener Barriers

• Unipolar Zener Barriers: These barriers are designed for single-channel applications, protecting one signal line.
• Bipolar Zener Barriers: These barriers protect two signal lines, making them suitable for differential signal transmission or applications requiring two-wire connections.
• Multi-Channel Zener Barriers: These barriers protect multiple signal lines, offering a compact solution for applications with several signals. They are often used in process control systems where multiple sensors or actuators need protection.

Types of Galvanic Barriers

• Intrinsically Safe Isolator Isolating Repeaters: These devices isolate and repeat analogue signals for safe monitoring and control of equipment in hazardous area.
• Intrinsically Safe Isolator Digital Relay Outputs: These barriers receive digital signals from the hazardous area, isolate them, and then use the signal to activate a relay in the safe area.
• Non-Intrinsically Safe Isolator Digital Inputs: These devices receive digital signals from a non-intrinsically safe area and provide an isolated digital signal for use in a safe area, ensuring the safety of the overall system.

Advantages of Using Zener and Galvanic Barriers

Zener and galvanic barriers offer several advantages for ensuring electrical safety in hazardous environments:

• Increased Safety: They prevent the ignition of flammable gases, vapours, or dust by limiting the electrical energy transferred to the hazardous area.
• Equipment Protection: Zener and galvanic barriers protect sensitive equipment and instrumentation from hazardous electrical faults, surges, and transients.
• Cost-Effectiveness: They can be a cost-effective solution for ensuring safety in hazardous areas, especially when compared to more complex protection methods.

Industrial Applications of Zener and Galvanic Isolation Barriers

Here are some key industrial applications of Zener and galvanic barriers as essential safety components.

Process Control Systems

Zener and galvanic barriers are widely used in process control systems found in industries such as oil and gas, chemical manufacturing, and pharmaceuticals. They provide protection for sensors, transmitters, and other control devices located in hazardous areas.

Industrial Automation

In industrial automation applications, Zener and galvanic barriers are employed to protect programmable logic controllers (PLCs), distributed control systems (DCS), and other automation equipment.

Instrumentation and Measurement

Zener and galvanic barriers are crucial for protecting measurement and instrumentation equipment used in hazardous environments. This includes devices such as pressure transmitters, temperature sensors, level indicators, and flow meters.

Power Distribution

Zener and galvanic barriers play a role in hazardous area power distribution systems. They are used to isolate and protect electrical circuits that supply power to equipment located in potentially explosive atmospheres, preventing the transfer of excessive voltage or current.

Communication and Networking

In hazardous environments, Zener and galvanic barriers are used to safeguard communication and networking equipment, such as fieldbus systems, Ethernet switches, and wireless devices.

How to Select the Suitable Zener and Galvanic Isolation Barrier

Choosing the appropriate Zener or galvanic isolation barrier is crucial for ensuring safety and optimal performance in hazardous environments. Here are some key factors to consider:

Hazardous Area Classification

• Hazardous Area Classification: Determine the specific hazardous area classification (e.g., Zone 0, Zone 1, Zone 2) where the barrier will be installed. This classification will influence the required protection level.
• Choose the Right Barrier: Ensure the barrier you select is certified and approved for use in the identified hazardous area classification.

Signal Type and Requirements

• Identify Signal Type: Determine whether you need to isolate analogue signals or digital signals.
• Consider Signal Characteristics: Evaluate factors like voltage level, current level, frequency, and data transmission speed to select a barrier that can handle the signal requirements without distortion or loss.

Power Requirements

• Determine the Power Source: Identify whether the barrier will be powered by the signal loop or require a separate power supply.
• Consider Power Consumption: If power consumption is a concern, choose a barrier with low power requirements, especially for intrinsically safe applications.

Certifications and Approvals

• Look for recognised certifications: Ensure the barrier has the necessary certifications and approvals for use in hazardous areas, such as ATEX, IECEx, or other relevant standards.
• Verify compliance with local regulations: Check that the barrier complies with any specific local regulations or requirements for hazardous area installations.

Trusted Zener & Galvanic Isolated Barriers Manufacturer, Supplier & Distributor in Malaysia

RS is a leading distributor of high-quality Zener and Galvanic isolation barriers in Malaysia.Our comprehensive selection caters to diverse needs, from simple single-channel barriers to sophisticated multi-channel isolators.

We source our Zener and galvanic barriers from trusted manufacturers like Endress+Hauser, GEORGIN, Phoenix Contact, and Eaton. Our online catalogue of products are competitively priced with options ranging from approximately RM 500 to over RM 2,000, catering to various budgets and application requirements.

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