Fig.1

The B-H and B-P curve of silicon steel sheet in DC bias"

Fig.2

The relationship between flux and exciting current in transformer DC bias"

Fig.3

The typical B- λ curve"

Fig.4

The wiring diagram of parallel testing with two same specification transformers"

"

Fig.5

Typical of measuring points noise and vibration signal frequency domain image"

Tab.2

Testing result of no-load DC bias with SSZ10–150000/220"

Fig.6

The change between exciting current and sound power level in no-load DC bias testing with SSZ10 – 150000/220"

Fig.7

DC bias testing noise and vibration spectrum characteristics with SSZ10 – 150000/220"

Fig.8

The coil arrangement of single-phase transformer core"

Tab.3

Testing result of no-load DC bias with DSP–223000/500"

Fig.9

The relationship between transformer noise and DC bias current"

Fig.10

The coil arrangement of single-phase and selfcoupled transformer core"

Fig.11

The curve of noise and DC bias"

Fig.12

The spectrum three-dimension graph of on-load magnetic bias-error gears – 2A in starting process"

Fig.13

The comparison of vibration acceleration of tank wall measuring point in several conditions"

Tab.4

Testing result of DC bias with ODFS–334000/500"