Effect of Arc Chute on DC Current Interruption by Liquid Nitrogen in HTS Electrical System of Distributed Propulsion Aircraft

The distributed propulsion aircraft with HTS electrical system is a novel concept for future airliners, which can reduce by more than 70% fuel burn and NO
_x
emissions. The circuit breakers ensure the security of this novel aircraft by isolating electrical faults timely. Solid-state circuit breakers (SSCBs) are preferred due to their fast response and high performance in the cryogenic circumstance. However, the high conduction loss of SSCBs impedes their further application. A mechanical switch using liquid nitrogen (LN
₂
) as an arc extinguishing medium shows excellent DC current interruption performance. The LN
₂
switch is characterized with extremely low contact resistance, and the proper use may reduce the conduction loss of power switches significantly. Nevertheless, the effect of metal type arc chutes on the arcing process in the LN
₂
is still not clear. Thus the objective of this paper is to understand the effect of metal type arc chutes on the current interruption performance of LN
₂
. Silicon iron arc chutes are employed. Neodymium (NdFeB) magnets are used to stretch the arc into the arc chutes. The maximum interrupting current is 1 kV/ 2 kA when only magnets are applied. Further applying the arc chutes leads to a significant drop in the arc voltage and interruption performance. Since the high relative permeability of silicon iron weakens the magnetic field acting on the arc, metal type arc chutes are not recommended. 1 kV / 10 kA fault current is successfully cleared by the combination of resistance type superconducting fault current limiter (R-SFCL) and LN
₂
switch with magnets, during which the R-SFCL responds to the fault within 420 μs, compensating the long clear time of the LN
₂
switch.