Multiple priorities, changing conditions of weather, manpower, equipment availability, unexpected emergencies, cascading failures, short periods of time to analyze and take action. Equipment availability affects scheduled maintenance and retrofit projects for instrumentation. Daily, weekly, monthly, and annual activities must adjust to weather induced changes in operation. Instrument failures occur without advance warning. Normal maintenance of instruments must be carried out in parallel with system expansion and retrofit projects. New types of cooling technology and operating procedures require on-going changes to the instrumentation. New proprietary vendor equipment and upgrades to existing equipment require learning new procedures and techniques to install and maintain control systems.