Abstract
AbstractCurrently, the International Electrotechnical Commission (IEC) standard (IEC62271-100) requires that the transformer limited fault (TLF) interruption shall be verified in the test duty T10, the amplitude factor of which is defined as 1.7 for the transient recovery voltage (TRV). But, the TRV measurements for the TLF at various transformers show that the factor is mostly lower than 1.7. The reason for the low values is considered to be that the short-circuit inductance of transformer at the TRV frequency region is lower than that at the power frequency, and consequently the factor is lower than the standard value 1.7. But, the frequency-dependence of the short-circuit inductance of transformer has not been clarified yet. We measured the short-circuit inductances of model transformer with and without the iron core. The short-circuit inductance with the iron core becomes small and equals to one without the iron core at the TRV frequency region. We concluded that this is the reason for the phenomena o...
Highlights
The capacity of power transformers tends to increase due to the increased capacity of the power systems
The reason is thought that the transient recovery voltage (TRV) frequency of transformer limited fault (TLF) interruption is over several kHz range, and the short circuit inductance of transformer will change at the high frequency region
The short-circuit inductance with the iron core is equal to the inductance without the iron core at high frequency
Summary
The capacity of power transformers tends to increase due to the increased capacity of the power systems. Transient Recovery Voltage (TRV) after current interruption, is a voltage oscillation which becomes dominant due to the leakage inductance and stray capacitance of transformer. The reason is thought that the TRV frequency of TLF interruption is over several kHz range, and the short circuit inductance of transformer will change at the high frequency region. The dependency of short circuit inductance of transformer on the frequency was investigated [7,8]. The frequency responses of short circuit inductance for the transformer model were measured with and without the iron core. It is thought that the change of the short circuit inductance value at high frequency region is caused by this phenomenon. The short circuit inductance becomes small in the high frequency region
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