1. Three single phase transformers, each of 100 KVA rating are connected in delta. If one of the transformers is taken out of service, the capacity of the system will be
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2. Three units of 1:5 transformer are connected in delta star to supply a 3-phase load from a 400V 3- Phase source. The line voltage for load side is
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3. In a transformer Pi is iron loss at rated voltage and Pc is copper loss at rated current. If the maximum efficiency occurs at 75% of full load, then which one of the following is correct?
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4. A transformer designed for operation on 60 hz supply is worked on 50Hz supply system without changing its voltage and current rating. When compared with full load effeciency at 60 Hz, The transformer efficiency on full load at 50Hz will be
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5. A single phase transformer has a maximum efficiency of 90% at full load and unity power factor. Efficiency at half load at the same power factor is
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6. In a transformer, primary and secondary voltages are
7. The dielectric strength of transformer oil is expected to be
8. In a transformer following winding has got more cross-sectional area
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9. A transformer can not raise or lower the voltage of dc supply because
10. Spacers are provided between adjacent coils
11. What KVA rating is required for a transformer that must handle a maximum load current of 8A with a secondary voltage of 2KV?
12. The hysteresis cycle for the material of a transformer is
13. Which of the following transformer is smallest?
14. In a 3-phase delta connected transformer, one of the phase is burnt up, then it works with
15. The magnetising current in a transformer is rich in
16. Varnishes protects the inslating material against
17. A transformer has negative voltage regulation when its load factor is
18. A transformer having 1000 turns in primary winding is connected to a single phase 250V ac supply. For inducing 400V in secondary winding , the number of turns in secondary winding must be
19. The leakage flux in transformer depends upon the
20. The full load copper loss of the transformer is twice its core loss. At what percentage of full load, will the efficiecy is maximum
21. The full load copper loss of the transformer is twice its core loss. At what percentage of full load, will the efficiecy is maximum
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