正常運(yùn)行時，二次電流產(chǎn)生的反向磁通抵消一次電流產(chǎn)生的磁通，使得鐵芯中總磁通較小，所以二次電壓接近為零。若二次斷開，二次電流為零，沒有反向磁通的抵消，一次電流產(chǎn)生的磁通就是總磁通，急劇變大，二次側(cè)將會出現(xiàn)高達(dá)數(shù)千伏的電壓，此時危險來臨。

Why Can't the Secondary Side of a Current Transformer Be Open-Circuited?

During normal operation, the reverse magnetic flux generated by the secondary current offsets the magnetic flux generated by the primary current. This keeps the total magnetic flux in the iron core relatively small, so the secondary voltage is close to zero. If the secondary side is disconnected, the secondary current becomes zero, and there is no offset from the reverse magnetic flux. The magnetic flux generated by the primary current then becomes the total magnetic flux, which increases sharply. As a result, the secondary side will develop a voltage as high as several thousand volts, and at this point, dangers arise.