Experimental investigation of different fault indicators for Synchronous machine failure analysis

Fault indicators signifying major failures in Synchronous machines (SM) are highlighted. A 15 megawatt (MW) SM was chosen in which, electro-mechanical faults were made by suitably altering physical disposition of machine parts. Finite element simulation of the motor model helped build signature for ideal and fault conditions in time and frequency domains for different fault indicators. Measurements were performed for stator parameters like phase voltage, current, stator current of the exciter and also through slip-ring for various rotor parameters, such as field winding voltage, current, shaft voltage and current. Comparison of simulation and measured results indicates field current and shaft voltage as two major fault detecting parameters. Stator exciter current proves to be an ideal indicator for semiconductor failures and even carries signatures for electro-mechanical faults. Notwithstanding the limitations of accessibility for measurement, information from field current and shaft voltage can be corroborated together for a combined fault diagnostic strategy.