Current Distribution of High Speed Parallel DC Fuses for HVDC Protection

This paper discusses fuse interrupting tests under 4000 V DC with low inductance. For the fuse breaking tests, the I2 current of IEC269 requires a pre-arcing of approximately 3 ms and arcing time about 5 ms with a transition time less than 1% of the total operation time. By contrast, in a case of short-circuit of a voltage source inverter, the current with very high di/dt occurs because of capacitor discharge with a very low inductance current loop. In this paper, to confirm the fuse breaking under very high di/dt condition, 3 large rated current fuses are connected in parallel and the breaking tests under 4000 V DC are validated in experiments. Finally, in a term of the fuse pre-arc i2t, the experimental results and the calculation using a simple model are compared.