Question: The permissible flux density in case of cold rolled grain oriented steel is around__________?

• 1. 1.7 Wb/m2
• 2. 2.7 Wb/m2
• 3. 3.7 Wb/m2
• 4. 4.7 Wb/m2

Question: Sumpner’s test is conducted on transformers to determine_____________?

• 1. temperature
• 2. stray losses
• 3. all-day efficiency
• 4. none of the above

Question: The dielectric strength of transformer oil is expected to be______________?

• 1. lkV
• 2. 33 kV
• 3. 100 kV
• 4. 330 kV

Question: No-load on a transformer is carried out to determine______________?

• 1. copper loss
• 2. magnetising current
• 3. magnetising current and loss
• 4. efficiency of the transformer

Question: The path of a magnetic flux in a transformer should have______________?

• 1. high resistance
• 2. high reluctance
• 3. low resistance
• 4. low reluctance

Question: The no-load current drawn by transformer is usually what per cent of the full-load current ?

• 1. 0.2 to 0.5 per cent
• 2. 2 to 5 per cent
• 3. 12 to 15 per cent
• 4. 20 to 30 per cent

Question: The degree of mechanical vibrations produced by the laminations of a transformer depends on____________?

• 1. tightness of clamping
• 2. gauge of laminations
• 3. size of laminations
• 4. all of the above

Question: A transformer core is laminated to__________?

• 1. reduce hysteresis loss
• 2. reduce eddy current losses
• 3. reduce copper losses
• 4. reduce all above losses

Question: In a transformer the energy is conveyed from primary to secondary_________?

• 1. through cooling coil
• 2. through air
• 3. by the flux
• 4. none of the above

Question: Which of the following does not change in a transformer ?

• 1. Current
• 2. Voltage
• 3. Frequency
• 4. All of the above