The detection of degraded materials in turbine generators by chemical analysis

It is of great importance to early detect problem in turbine generators. In the diagnosis technology field, electrical testing such as partial discharge or resistance measurement has been intensively studied so far, but it is still insufficient to attain accurate diagnosis. Chemical analysis of the coolant gas is a candidate method which may enable early detection of problems. An instrument to collect the organic molecules in the generator coolant-gas was manufactured. Over 100 kinds of organic molecules containing aromatic and aliphatic hydrocarbons were detected by GC/MS and compared with organic thermal decomposition products from the insulating material. Some products were regarded as indication molecules informing local overheating. The changes of the organic product concentration in a generator were also estimated as a function of operation time. The concentration gradually increased and seemed to saturate. A simple kinetic model revealed the relationship between equilibrium concentration and individual decomposition rate of each material.