Question: The stator of a D.C. machine comprises of_____________?

• 1. main poles
• 2. interpoles
• 3. frame
• 4. all of the above

Question: Which of the following in an application of D.C. motors?

• 1. Traction
• 2. Drives for process industry
• 3. Battery driven vehicles
• 4. All of the above

Question: The cylindrical windings using circular conductors are used for current rating of____________?

• 1. upto 20 A
• 2. upto 40 A
• 3. upto 60 A
• 4. upto 80 A

Question: The laminations of the armature of a D.C. machine are usually ___________ thick?

• 1. 0.1 to 0.2 mm
• 2. 0.2 to 0.3 mm
• 3. 0.3 to 0.4 mm
• 4. 0.4 to 0.5 mm

Question: ___________ brushes are fragile and cause excessive wear of commutator?

• 1. Natural graphite
• 2. Hard carbon
• 3. Electro graphitic
• 4. Metal graphite

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