Large current interruption, arc, crack, crack resistance, copper-tungsten alloy, tungsten grain size, GCB (gus circuit breaker)
Copper-tungsten contacts are known to have hexagonal-shaped cracks on the surface due to thermal shock of arc when interrupting a large current. These cracks are likely to be cathode spots and accelerate the contact erosion as well as hindering extinction of arc. In addition, such cracks stretch to the inside of the contact in an alternating succession of current interruption, and eventually the contact becomes defective. This time, we report our newly developed contact material which has fewer cracks when interrupting a large current.