外文翻譯---負載運行的變壓器-其他專業(yè)-閱讀頁
2025-02-08 09:45本頁面
【正文】 equivalent winding having the same number of turns 1N as the primary. With 2N changes to 1N , since the are proportional to turns, 2212 )/(39。39。 NINI ? must be equal to 22NI .. 2122 )/( INNI ? . For impedance , since any secondary voltage V bees VNN )/( 21 , and secondary current I bees INN )/( 12 , then any secondary impedance, including load impedance, must bee IVNNIV /)/(39。 221? . Consequently, 22212 )/(39。 XNNX ? . If the primary turns are taken as reference turns, the process is called referring to the primary side. There are a few checks which can be made to see if the procedure outlined is valid. For example, the copper loss in the referred secondary winding must be the same as in the original secondary otherwise the primary would have to supply a different loss power. 39。 222 RI must be equal to 222RI . ）222122122 /()/( NNRNNI ?? does in fact reduce to 222RI . Similarly the stored magic energy in the leakage field )2/1( 2LI which is proportional to 2239。39。39。2R , 39。2I , measurements from the primary terminals would be unable to detect any difference in secondary ampereturns, kVA demand or copper loss, under normal power frequency operation. There is no point in choosing any basis other than equal turns on primary and referred secondary, but it is sometimes convenient to refer the primary to the secondary winding. In this case, if all the subscript 1’s are interchanged for the subscript 2’s, the necessary referring constants are easily found。1 RR ? , 2139。 similarly 139。 XX ? . The equivalent circuit for the general case where 21 NN ? except that mr has been added to allow for iron loss and an ideal lossless transformation has been included before the secondary terminals to return 39。 capacitance effects must be taken into account whenever the rate of change of voltage would give rise to appreciable capacitance currents, dtCdVIc /? . They are important at high voltages 8 and at frequencies much beyond 100 cycles/sec. A further point is not the only possible equivalent circuit even for power frequencies .An alternative , treating the transformer as a threeor fourterminal work, gives rise to a representation which is just as accurate and has some advantages for the circuit engineer who treats all devices as circuit elements with certain transfer properties. The circuit on this basis would have a turns ratio having a phase shift as well as a magnitude change, and the impedances would not be the same as those of the windings. The circuit would not explain the phenomena within the device like the effects of saturation, so for an understanding of internal behaviour . There are two ways of looking at the equivalent circuit: (a) viewed from the primary as a sink but the referred load impedance connected acros
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鄂ICP備17016276號-1