Articles

Intrinsic Safety Made Easy

Ts. Dr. Teik Hua Kuan

• Intrinsic Safety
• Hazardous Area (Ex)

This paper aims to provide a quick understanding on the concept of Intrinsically Safe, various available intrinsically safe products and their technologies used including HART and Foundation Fieldbus (FISCO solution and Fieldbus Barrier). The paper begins by introducing the origin and how the concept of Intrinsically Safe (I.S.) is started then it move on to explain how the zener and galvanical/isolation designed and its working principles with the famous ignition curves. barriers are It then attempt to provide a brief comparison on conventional point to point DIN rail mounting barrier solution to a system approach solution. The paper also provides some background on HART and points to take note when using HART and HART Mutiplexer as HART protocol has been available for quite some time. Foundation Fieldbus is a hot topic as a number of recent projects in Malaysia applied foundation Fieldbus technology. This paper outline the concept of Foundation Fieldbus and explain the different between FISCO and Fieldbus Barrier and also point to take note when selecting them.

Practical Approach on Surge Protection Device For Ex Application

Ts. Dr. Teik Hua Kuan

• Surge Protection
• Hazardous Area (Ex)

A reputable Surge Protection Device (SPD) manufacturer designed, tested and produced SPD complying with the internationally accepted standard such as UL 96A, UL1449, IEC 61643, IEC 62305 and etc., where this standard put in place the requirement on the thermal disconnect to prevent SPD from overheated catching fire, housing material from releasing toxic gases and so on. Therefore, when an SPD which carried international approval, the selection is mainly focused on the let-through voltage, kA rating and protection class or zone per ANSI/IEEE C62.4 and IEC 62305-4. This is sufficient when the application is for a safe area (no present of explosive gases). However, when the application involves the presence of explosive gas in a hazardous area, for example, in the Oil and Gas industry, additional consideration will be required. This paper discussed the application and consideration of SPD for hazardous areas with various explosion protection techniques.

Verification of Intrinsic Safety on Instrumentation Loop

Ts. Dr. Teik Hua Kuan

• Intrinsic Safety
• Hazardous Area (Ex)
• Instrumentation

Intrinsic safety is one of the explosion protection techniques implemented in an industry where a flammable substance is present. It is a technique that reduces the electrical energy level at the hazardous area below the ignition curve so that it is not sufficient to initiate an explosion. In addition to limiting the energy to the field, the energy stored in the circuit and thermal ignition due to hot surfaces in hazardous areas must also be considered. Intrinsically safe is the preferred explosion protection method for instrumentation and control signals as it allows live maintenance, the use of an uncertified simple apparatus, and is applicable to all Zones. All intrinsically safe circuits must carry out a safety assessment and verify their compliance with intrinsic safety before implementation to avoid explosion. The verification process could be complex for mixed circuits and non-simple intrinsically safe systems; moreover, there has been much confusion for many years until the 4th Edition of the installation stan dard, IEC 60079-14, provided a clearer picture. This paper carries out an intrinsic safety verification assessment on a mixed circuit involving surge protection devices according to EC and NEC standards. It also highlights the common mistake made by system designers when verifying the safety parameters.

Surge Protection Device for Ex Application

Ts. Dr. Teik Hua Kuan

• Surge Protection
• Hazardous Area (Ex)

A modern process plant is controlled, operated and safeguarded by the sophisticated distributed control system or a programmable logic controller and an emergency shutdown system. This process plant's operation could be seriously affected by lightning, electrical switching, and power outrage. Lightning propagation can travel kilometers away, which has the risk of disturbing the control system's operation. The process plant's control system could damage when it is subjected to surges induced by lightning, power outrage, or heavy load switching. To protect equipment damage from these surges surge protection device is required. A number of the process plant uses flammable material for its production or during the manufacturing processes, explosive gas or vapor is released created an explosive atmosphere known as hazardous (Ex) area. Surge protection device mounted in the Ex area or used in the Ex control loop needs to be carefully selected to protect the equipment and at the same time, it does not become a source of ignition. This paper provides practical consideration and comprehensive detail in revealing the science and engineering behind Ex application on surge protection devices. The technical presentation is limited to equipment protection; structural protection against lightning will not be discussed here.