A. minimum
B. maximum
C. nil
D. none of the above
Related Mcqs:
- The cold rolled grain oriented steel has _________ permeability in the direction of the grain orientation?
A. minimum
B. maximum
C. nil
D. none of the above - For 275 kV transformers, using cold rolled grain oriented steel, which of the following values of flux density may be used?
A. 1.0 Wb/m2
B. 1.1 Wb/m2
C. 1.3 Wb/m2
D. 1.6 Wb/m2
E. None of the above - Hot rolled sheets have ___________ value of permeability?
A. zero
B. low
C. high
D. none of the above - In transformers using hot rolled steel, the cross-section of the yoke is made about __________ greater than that of the core?
A. 5 percent
B. 10 percent
C. 15 percent
D. 30 percent
E. none of the above - The usual values of maximum flux densities for distribution transformers using hot rolled silicon steel are______________?
A. 0.5 to 0.8 Wb/m2
B. 0.8 to 1.0 Wb/m2
C. 1.1 to 1.35 Wb/m2
D. 1.4 to 1.8 Wb/m2 - __________ has a low relative permeability and is used principally in field frames when cost is of primary importance and extra weight is not objectionable?
A. Cast steel
B. Aluminium
C. Soft steel
D. Cast iron - The noise produced by a ___________ cooled machine is less as the rotor moves in a medium of smaller density?
A. air
B. hydrogen
C. either A. or B.
D. none of the above - In self cooled motors the cooling time constant is about ___________ than the heating time constant because cooling conditions are worse at standstill?
A. 2 to 3 times greater
B. 3 to 4 times greater
C. 4 to 5 times greater
D. none of the above - The laminations of the armature of a D.C. machine are usually ___________ thick?
A. 0.1 to 0.2 mm
B. 0.2 to 0.3 mm
C. 0.3 to 0.4 mm
D. 0.4 to 0.5 mm - ___________ brushes are fragile and cause excessive wear of commutator?
A. Natural graphite
B. Hard carbon
C. Electro graphitic
D. Metal graphite
