The company has signed a deal with utility Alinta Energy to utilize its DIRIS and TurboRotoscan systems to inspect 19 generators manufactured by GE, Alstom, Mitsubishi and Brush at seven Alinta plants.
Gareth Williams, manager of Alinta’s power generation engineering services, said that “the biggest win” for the company was “the ability to use this technology on non-GE units and apply it across our whole fleet. This makes such inspections quicker and easier to perform and is endorsed as a best practice by our insurance company, which indicates that most generator claims arise through rotor removal and replacement activities.”
He added: “Proving the technology’s reliability was important because the generator monitoring system provides the current condition of the generator and indicates any issues or early warnings of failures. It also provides us with greater flexibility as the inspection work can be done while the generator rotor remains in place.”
The DIRIS robot will provide Alinta with robotic instrumentation and tooling to allow remote inspection of the turbogenerator. It performs critical tests of the generator stator iron core laminations, stator radial wedging system and conducting a visual (video-type) inspection of the inside surfaces of the rotor and stator.
These tests would normally be part of a typical overhaul regime after a lengthy process of removing the rotor and utilizing manual and semi-automated tooling. GE said that the low flux test “permits the identification of short circuits between the stator iron core laminations, which could otherwise develop into critical hot spots and severely damage the generator”.
The tightness test of the radial wedging system permits identifying loose wedges, which could otherwise promote movement of the stator bars and damage to the stator winding insulation system.
Meanwhile, the robotic technology TurboRotoscan will perform inspections of the generator retaining rings while the rotor remains in place and while the retaining rings are mounted on the rotor. The scanner also contains an eddy current probe to check the retaining ring outside surfaces.
The new generator inspections will begin next month and be performed through to 2020.