电流互感器二次侧不许开路运行。因为接在电流互感器副线圈上的仪表线圈的阻抗很小，相当于在副线圈短路状态下运行。互感器副线圈端子上电压只有几伏。因而铁芯中的磁通量是很小的。原线圈磁动势虽然可达到几百安或上千安匝或更大。但是大部分被短路副线圈所建立的去磁磁动势所抵消，只剩下很小一部分作为铁芯的励磁磁动势以建立铁芯中的磁通。如果在运行中时副线圈断开，副边电流等于零，那么起去磁作用的磁动势消失，而原边的磁动势不变，原边被测电流全部成为励磁电流，这将使铁芯中磁通量急剧，铁芯严重发热以致烧坏线圈绝缘，或使高压侧对地短路。另外副线圈开路会感应出很高的电压，这对仪表和操作人员是很危险的所以电流互感器二次侧不许断开。
No open circuit operation is allowed on the secondary side of current transformer. Because the impedance of the instrument coil connected to the secondary coil of the current transformer is very small, it is equivalent to running in the condition of short circuit of the secondary coil. The voltage on the terminal of the secondary coil of the transformer is only a few volts. Therefore, the magnetic flux in the core is very small. Although the magnetic potential of the original coil can reach several hundred amperes or thousands ampere turns or greater. However, most of them are offset by the demagnetization potential created by the short-circuit secondary coil, leaving only a small part of the excitation potential as the core to establish the flux in the core. If the secondary coil is disconnected and the secondary side current equals zero during operation, the magnetic momentum acting as demagnetization disappears, while the original side's magnetic momentum remains unchanged, and all the measured currents on the original side become excitation currents, which will make the magnetic flux in the core sharply increase, and the iron core heats so that the insulation of the coil is damaged or the high-voltage side is short-circuited to the ground. In addition, the secondary coil open circuit will induce a high voltage, which is very dangerous to the instrument and operator, so the secondary side of the current transformer should not be disconnected.
如果电压互感器的二次侧运行中短路，二次线圈的阻抗大大减小，就会出现很大的短路电流，使副线圈因严重发热而烧毁。因此在运行中互感器不允许短路。一般电压互感器二次侧要用熔断器。只有35千伏及以下的互感器中，才在高压侧有熔断器其目的是当互感器发生短路时把它从高压电路中切断，短路电阻小，则电压与电阻的商大，即电流大，危险！
If the secondary side of the voltage transformer is short-circuited in operation, the impedance of the secondary coil will be greatly reduced, and a large short-circuited current will appear, which will cause the secondary coil to burn down due to serious heating. Therefore, short circuit is not allowed in guanl.37ix.com.cn jianchaj.37ix.com.cn gangsug.37ix.com.cnboluoji.07858.netkongzhifa.89ix.comboliji.89ix.comoperation. Generally, fuses are used on the secondary side of voltage transformers. Only in the transformer with 35 kV or less, there is a fuse on the high voltage side. Its purpose is to cut it off from the high voltage circuit when the transformer short circuit occurs. If the short circuit resistance is small, the quotient of voltage and resistance will be large, that is, the current is big and dangerous.