Question: A current density of __________ is ilsed for large power transformers with forced circulation of oil or with water cooling coils?

• 1. 1.5 to 2.5 A/mm2
• 2. 3.5 to 4.5 A/mm2
• 3. 4.0 to 5.0 A/mm2
• 4. 5.4 to 6.2 A/mm2

Question: Which of the following is the basic consideration in the design of insulation ?

• 1. Electrical considerations
• 2. Mechanical considerations
• 3. Thermal considerations
• 4. All of the above

Question: The voltage control in electric supply networks in required on account of which of the following reasons ?

• 1. Adjustment of voltage at consumers premises within statutory limits
• 2. Control of active and reactive power
• 3. Adjustment of short period daily and seasonal voltage variations in accordance with variations of load
• 4. All of the above

Question: Transformers with a capacity of up to __________ have a cooling radiator system with natural cooling?

• 1. 2 MVA
• 2. 5 MVA
• 3. 7.5 MVA
• 4. 10 MVA

Question: The heat dissipating capability of transformers of ratings higher than 30 kVA in increased by providing which of the following ?

• 1. Corrugations
• 2. Fins
• 3. Tubes
• 4. All of the above

Question: The forced oil and air circulation method is usual one for transformers of capacities____________?

• 1. upto 5 MVA
• 2. upto 10 MVA
• 3. upto 20 MVA
• 4. 30 MVA upwards

Question: Disc windings are primarily used in_____________-?

• 1. short capacity transformers
• 2. medium capacity transformers
• 3. high capacity transformers
• 4. any of the above

Question: Helical windings are used in________________?

• 1. distribution transformers
• 2. power transformers
• 3. shell type transformers
• 4. none of the above

Question: The cold rolled grain oriented steel has ___________ permeability in the direction of the grain orientation?

• 1. minimum
• 2. maximum
• 3. nil
• 4. none of the above

Question: Multi-layer helical windings are commonly used in the transformers as high voltage windings_______________?

• 1. upto 20 kV
• 2. upto 50 kV
• 3. upto 80 kV
• 4. for 110 kV and above