In a complex operation like power generation nearly all components are critical, as the loss of one unit can affect many other units down the line, effectively taking a plant offline, or severely limiting the output. The most critical assets that should be closely monitored are turbines, generators, boiler feed-water pumps and ID/FD Fans. These most critical assets have no backup units associated, and machine failure would severely de-rate the plant output, or take it offline completely. If this occurred the asset replacement cost is extremely high, and time consuming to get back online. Generally, a majority of other units can be offline for extended periods of time with reduced impact to production.