A) Stainless steel B) Hard pressed carbon C) Copper tungsten alloy D) Porcelain. Ans : (C)
A) power factor B) armature reaction C) circuit conditions D) all of the above. Ans : (D)
A) peak voltage B) supply voltage C) restriking voltage D) recovery voltage. Ans : (C)
A) material of contacts B) high temperature of surrounding medium C) increase of mean free path D) increase of field strength. Ans : (A)
A) Conductor of electricity B) Dielectric C) Semi-conductor D) Inactive gas. Ans : (B)
A) the ambient temperature B) the amount of surface contamination C) the shape of the contact faces D) the mechanical force applied. Ans : (A)
A) Minimum oil circuit breaker B) Vacuum circuit breaker C) Air break circuit breaker D) SF6 gas circuit breaker. Ans : (C)
A) Low specific resistance and low melting point B) Low specific resistance and high melting point C) High specific resistance and low melting point D) High specific resistance and high melting point. Ans : (A)
A) 10 A B) 25 A C) 50 A D) 100 A. Ans : (D)
A) Leading the arc current by 90o B) Lagging the arc current by 90o C) In phase with the arc current D) In phase opposition to the arc current. Ans : (C)