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Questions and Answers
What is the current at the secondary side of a transformer with 400 primary turns and 100 secondary turns, if a 20 A current is flowing through the primary?
What is the current at the secondary side of a transformer with 400 primary turns and 100 secondary turns, if a 20 A current is flowing through the primary?
- 800 A
- 80 A
- 5 A
- 40 A (correct)
Why is a transformer considered an efficient machine?
Why is a transformer considered an efficient machine?
- It is a static machine
- The machine can carry overloads up to 50% of its capacity
- Its primary and secondary windings are electrically linked
- Its copper losses are practically negligible (correct)
In a 120-V dc shunt motor rated at 6 hp with armature and shunt field resistances of 0.1 Ω and 100 Ω, if the motor draws a rated armature current of 50 A, what is the efficiency of the motor?
In a 120-V dc shunt motor rated at 6 hp with armature and shunt field resistances of 0.1 Ω and 100 Ω, if the motor draws a rated armature current of 50 A, what is the efficiency of the motor?
- 74.6%
- 73.4% (correct)
- 75.3%
- 72.8%
In a 480/240 V transformer with the secondary open circuited, what is the core loss component current when the primary current is 0.15 A at a power factor of 0.6?
In a 480/240 V transformer with the secondary open circuited, what is the core loss component current when the primary current is 0.15 A at a power factor of 0.6?
If a transformer has 240 turns on the primary and 30 turns on the secondary, and the primary draws 0.3 A from the supply lines, what is the current in the secondary side?
If a transformer has 240 turns on the primary and 30 turns on the secondary, and the primary draws 0.3 A from the supply lines, what is the current in the secondary side?
In a transformer with a load current of 4 A at 0.25 power factor, which resistance value represents the reactive component?
In a transformer with a load current of 4 A at 0.25 power factor, which resistance value represents the reactive component?
