在用瞬时值分析时容易出现疏漏，得出两者相位差等于π/2 的错误结论.本文用矢量法分析理想变压器各物理量之间的相位

关系，并给出正确的瞬时值分析过程，从而指出上述错误结论的来源.

primary coil are in phase. However，many beginners are confused about this point. As a result，possible errors and

omissions in instantaneous value analyses can lead to a clearly wrong conclusion that there is a phase difference of

π/2 between the voltage and the current of the primary coil. In this paper，the phase relations between the physical

quantities of an ideal transformer are analyzed using vector diagrams. The correct instantaneous value analysis is also

given，so that the main reason of the wrong conclusion is pointed out.