Question: ____________ is the common method of applying brushes to the commntator?

• 1. Radial
• 2. Trailing
• 3. Reaction
• 4. All of the above

Question: The insulation between windings and grounded core and the insulation between the windings of the same phase is called__________________?

• 1. minor insulation
• 2. major insulation
• 3. either of the above
• 4. none of the above

Question: The surge phenomenon is particularly important in case of_______________?

• 1. low voltage transformers
• 2. medium voltage transformers
• 3. high voltage transformers
• 4. any of the above

Question: A practical formula for determining the thickness of insulation between low voltage and high voltage windings is__________________?

• 1. 1 + 0.2 kVmm
• 2. 2 + 0.5 kVmm
• 3. 4 + 0.7 kV mm
• 4. 5 + 0.9 kV mm

Question: For large power transformers, self oil cooled type or air blast type which of the following values of current density may be used?

• 1. 1.0 to 1.2 A/mm2
• 2. 1.5 to 2.0 A/mm2
• 3. 2.2 to 3.2 A/mm2
• 4. 3.2 to 4.2 A/mm2

Question: The usual values of maximum flux densities for distribution transformers using hot rolled silicon steel are______________?

• 1. 0.5 to 0.8 Wb/m2
• 2. 0.8 to 1.0 Wb/m2
• 3. 1.1 to 1.35 Wb/m2
• 4. 1.4 to 1.8 Wb/m2

Question: The flash point of transformer oil should be higher than_______________?

• 1. 40°C
• 2. 60°C
• 3. 80°C
• 4. 104°C

Question: The high voltage winding is usually which of the following type ?

• 1. Cylindrical winding with circular conductors
• 2. Cross-over winding with either circular or small rectangular conductors
• 3. Continuous disc type winding with rectangular conductors
• 4. All of the above types

Question: D.C. windings are____________?

• 1. sometimes 2-layer type
• 2. never 2-layer type
• 3. always 2-layer type
• 4. none of the above

Question: For 275 kV transformers, using cold rolled grain oriented steel, which of the following values of flux density may be used?

• 1. 1.0 Wb/m2
• 2. 1.1 Wb/m2
• 3. 1.3 Wb/m2
• 4. 1.6 Wb/m2