Power transformers 11 Cellulose 3 Technology: general issues 3 Vibration analysis 3 ABAQUS 2 Acoustic detection 2 Acoustic signals 2 Cellulose degradation 2 Compressive stress 2 DC bias 2 DC transformers 2 Data statistics 2 Distribution regularities 2 Early-warning method 2 Finite element analyse 2 Finite element method 2 Frequency domain analysis 2 Long-term vibration 2 Mechanical stress 2 Multiparameters 2 Normal state 2 Oil filled transformers 2 Oil-impregnated pressboard 2 Operation state 2 Partial discharges 2 Stress aging 2 Thermal 2 Thermal–electrical–mechanical stress aging 2 Transformer 2 Transformer substations 2