To limit current chopping in Vacuum Circuit Breakers (VCB), the contact material used has
- A. Low vapour pressure and high conductivity properties
- B. High vapour pressure and high conductivity properties
- C. High vapour pressure and low conductivity properties
- D. The inductance and capacitance of the system only
Answer: C. High vapour pressure and low conductivity properties
Explanation: To limit current chopping in vacuum circuit breakers, contact alloys (such as Cu-Bi or Cu-Cr) must have high vapor pressure and low thermal conductivity to maintain metal vapor at low current zero crossings.