Three Phase Distribution Transformer FAQ 2

11. For three phase distribution transformer in operation, the upper oil temperature should not exceed _______ (D)

A, 80°C B, 85°C C, 90°C D, 95°C

12. When the load increases, the secondary current of the three phase distribution transformer will _______ (C)

A. Decrease B. Remain unchanged C. Increase proportionally D. Significantly increase

13. The capacities of two transformers T1 and T2 meeting the parallel conditions are S1 and S2 respectively. It is known that S1>S2, after paralleling, when the load gradually increases, _____（B）

A. T1 is fully loaded first B. T2 is fully loaded first

C. T1 and T2 are fully loaded at the same time D. Unable to judge

14. When the oil-immersed power transformer has a large capacity, it is equipped with a "breather", and the source of its respiration is mainly _____ (C)

A. Changes in load current B. Changes in ambient temperature

C. Expansion and contraction of the shell D. Changes in ambient air pressure

15. The 10kV system is a running three phase distribution transformer. When a single-phase ground fault occurs on the primary line, if the transformer is not overloaded, then _____. (B)

A. Still running continuously B. Only allowed to run for two hours

C. Only allowed to run for half an hour D. Stop running immediately

16. The rated capacity of a transformer is: the three phase distribution transformer tap changer is in the II gear, and the rated voltage of the rated frequency is _____ guaranteed value once. (D)

A. Active power input B. Apparent power input C. Active power output D. Apparent power output

17. For a transformer in operation, the magnetic flux in the iron core is determined by _____ (B)

A. Supply voltage B. Load current C. Core material D. Output power

18. The voltage of the transformer remains the same, when the load increases, the output voltage will _____ (C)

A.increased B.decreased  C.unchanged  D.indeterminate

19. The secondary rated voltage of the transformer refers to the voltage in which of the following situations_____（A）

A. Full load B. Empty load C. Light load D. Any load

20. When the power supply voltage increases, the no-load current of the transformer will _____ (B)

A. Decrease B. No change C. Increase proportionally D. Significantly increase