ABB has announced that it has completed commissioning the turbine control retrofit project for the 750MW Unit 5 at the Four Corners power plant in New Mexico, USA. The plant placed another order for an identical unit known as Unit 4, with increased scope. The scope of the project included a retrofit for one of the turbine rotors, as well as the mechanical-hydraulic controls for the 750MW main steam turbine. The project involved removing the original mechanical governor and retrofitting the wet box actuator and interface to the steam valves, as well as a new overspeed trip system. The controls update included an automatic turbine start-up program and rotor stress monitoring. The expanded scope of work for Unit 4 will include replacing low pressure pilot valve actuators on the boiler feed-pumps with the final element high pressure actuators supplied by the new hydraulic skid to be installed for the main unit. The existing vibration monitoring system will also be replaced with ABB’s turbine vibration monitoring system. Installation and start-up of Unit 4 is scheduled for spring 2010.