Surge Protection Device for Ex Application

Abstract

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.

Verification of intrinsic safety on instrumentation loop

“…Entity parameter verification for two SPDs connected in series at the field18 T A B L E 8 Intrinsically safe verification for nonsimple IS system with two SPDs in series connection…”