Reliability is one of the most important aspects we should be focused on especially when it comes to Plant Maintenance. Frequent shutdowns in plant could be caused by poor maintenance management and lack of advance tools to keep the system running. For a plant working 24/7, most of the running equipments should be treated critically and monitored regularly. However, Redundant Systems are used to save the plant from shutdowns if failure occurs. Aside from back-up power we should always thought of back-up systems that will manually or automatically take over the operations in the event of fault or alarm. In this article, I will share with you the redundant systems that I have encountered by working in Maintenance Department and Engineering Design.