Intrinsic Safety: Enhancing Power Output for Hazardous Environments
Introduction
Intrinsic safety is a crucial technique used to ensure safety in hazardous environments where the presence of flammable gases poses a constant threat. It allows for the use of electrical equipment in areas classified as Zone 0 or 20, where hazards are continuously present for long periods. With intrinsic safety, live maintenance can be performed safely, making it an indispensable technique in industries such as oil and gas, marine, and logistics.
The concept of intrinsic safety originated in the early twentieth century as a means to prevent the ignition of firedamp, primarily methane, and other volatile gases in coal mines. Over time, national standards and regulations were established, and various advancements in intrinsic safety technology were introduced. In this article, we will explore the evolution of intrinsic safety, the challenges it addresses, and the potential for increasing power output in hazardous area apparatus.
The Evolution of Intrinsic Safety
Applications of Intrinsic Safety
Initially, intrinsic safety was primarily used for transferring the output of hazardous area sensors, such as thermocouples, RTDs, strain gauges, and switch contacts, from a hazardous to a safe area. However, advancements in semiconductor technology enabled the development of active intrinsically safe hazardous area equipment powered from the safe area
In the mid to late 1960s, semiconductors that functioned at low voltages and currents, became available. This enabled the development of active intrinsically safe equipment, including proximity detectors and loop-powered transmitters. Integrated circuits and low-power microcontrollers further expanded the applications of active intrinsically safe equipment.
Despite advancements in intrinsically safe power, practical intrinsic safety remains a low-power technique. Commercially available Zener barriers and galvanic isolators can supply around 0.8W of matched power in a hydrogen atmosphere. While this is sufficient for many instrumentation applications, it limits the power of hazardous area apparatus powered from a safe area. However, innovative design approaches can increase the usable power in a hazardous area by approximately five times.
Increasing Usable Power in Hazardous Areas
To increase the usable power in hazardous areas, three key areas need to be considered: the interface between safe and hazardous areas, transmission of power to the hazardous area apparatus, and limitation of energy storage and high surface temperatures in the apparatus.
Interface Design and Limitations
International intrinsic safety standards define ignition curves for resistive limited sources, which determine the minimum voltage and current that may cause ignition. These curves vary for different gas groups. The interface between the safe and hazardous areas, whether it’s a Zener barrier, galvanic isolator, or power supply with an intrinsically safe output, must adhere to these ignition curves. A 1.5 factor of safety is typically applied to these curves for hazardous areas in Zone 0 or 1.
Power Transmission
Power transmission from the interface to the hazardous area apparatus is limited by parameters such as capacitance and inductance. International standards define maximum capacitance and inductance values based on the gas in which the apparatus is located. The output voltage and current of the interface determine these values. Intrinsic safety standards also provide guidelines for cable length, considering factors such as the L/R ratio.
Overcoming Power Limitations
In some cases, power limitations can be overcome by employing alternative explosion protection methods, such as Ex m encapsulation, Ex d flameproof, or Ex e increased safety. However, one elegant solution that retains the benefits of intrinsic safety is combining multiple galvanically isolated power supplies at the hazardous area apparatus. This reduces the current flowing in each conductor and allows for longer cable lengths.
Extending Usable Power: A Case Study
At ADOTT Solutions, we specialize in engineering solutions for hazardous environments. One of our recent projects involved the development of a cutting-edge Portable Remote Controller System for power-demanding applications in explosive and non-explosive environments. This project required us to overcome challenges such as wide operational temperature range, size constraints, and weight limitations.
To meet the unique requirements of the marine, logistics, and oil & gas industries, our team leveraged our expertise in intrinsic safety engineering. We implemented innovative problem-solving techniques and collaborated closely with the client to ensure a user-centric design. The result was a comprehensive Ex-system that enhanced the product’s functionality and versatility.
The Portable Remote Controller System incorporated a range of features, including an Ex-touch screen display, Windows-compatible Ex-hardware, a high-capacity Ex battery with Over-Current and Over-Voltage protection modules, and Ultra High-Frequency radio communication for reliable data transmission. Precision engineering allowed us to meet size and weight constraints, while thorough testing and validation ensured compliance with international explosion-proof industry standards.
Conclusion
Intrinsic safety is a critical technique for ensuring safety in hazardous environments. While it remains a low-power protection concept, advancements in technology and innovative design approaches have the potential to increase the usable power in hazardous area apparatus. By carefully considering the interface design, power transmission, and energy limitations, it is possible to extend the scope of intrinsically safe equipment to include applications that require higher operational power.
ADOTT Solutions, with our expertise in intrinsic safety engineering, continues to push the boundaries of what is possible in hazardous environments. Our recent project, the Portable Remote Controller System, exemplifies our commitment to delivering outstanding performance, reliability, and safety compliance. Trust ADOTT Solutions to provide comprehensive engineering solutions for your hazardous area requirements.
Source article: www.hazardexonthenet.net
