在电气工程领域，有一个被广泛认可的准则：“电流互感器的二次侧不能开路，电压互感器二次侧不能短路。”这句话在实际工作中被视为“圣经”般的存在。电气工程师们在进行电流互感器二次线的拆除工作时，都会先用短接片或短接线将二次侧短接，然后再进行拆线或接线操作。这种做法是确保人员安全的正确方式。
In the field of electrical engineering, there is a widely recognized criterion: "The secondary side of the current transformer shall not be open, and the secondary side of the voltage transformer shall not be short." This phrase is considered "biblical" in practice. When removing the secondary line of the current transformer, electrical engineers will first short-circuit the secondary side with a short-circuit splinter or a short-circuit cable, and then disassemble or connect the cable. This approach is the right way to ensure the safety of personnel.
我个人在拆除电度表的电流线时，就曾亲身经历过短接不牢靠导致端子处噼里啪啦放电的现象。那么，为什么电流互感器的二次侧不能开路呢？其背后的原理是什么？又会产生什么样的后果呢？接下来，我们将对此进行详细的分析，以便大家能够更好地理解。
I personally experienced the phenomenon of crackling discharge at the terminal when I removed the current line of the meter. So, why can't the secondary side of the current transformer be open? What is the principle behind it? What are the consequences? Next, we will carry out a detailed analysis of this, so that you can better understand.
正常运行中的电流互感器
Current transformer
电流互感器正常工作的时候，次级所接负载为电流表或电度表电流线圈以及变送器等，这些线圈的阻抗都很小，基本上运行在短路状态。
When the current transformer works normally, the secondary load is ammeter or watt-hour meter current coil and transmitter, etc. The impedance of these coils is very small, basically running in the short-circuit state.
这种情况下，电流互感器的一次电流和次级电流所产生的磁通相互抵消，使铁芯中的磁通密度维持在较低水平，通常在零点几特斯拉（磁通密度的单位：T），由于次级电阻很小，所以次级电压也很低。
In this case, the magnetic flux generated by the primary current and secondary current of the current transformer cancels each other, so that the magnetic flux density in the core is maintained at a low level, usually at a few tenths of a tesla (the unit of magnetic flux density: T), because the secondary resistance is small, the secondary voltage is also low.
电流互感器二次侧开路情况下
Secondary side open circuit
当电流互感器次级绕组开路时，这时候一次电流如果没有变化，二次回路断开，或者电阻很大，那么二次侧的电流为0，或者非常小，二次线圈或铁芯的磁通量就很小，不能抵消掉一次磁通量。这时候一次电流全部变为励磁电流，使铁心饱和，这个变化是突然的，叫突变，它的磁通密度高达几个特斯拉以上。
When the secondary winding of the current transformer is open, if the primary current does not change, the secondary circuit is disconnected, or the resistance is very large, then the secondary side of the current is 0, or very small, the magnetic flux of the secondary coil or core is very small, and the primary magnetic flux cannot be offset. At this time, all the primary current becomes exciting current, so that the core is saturated, this change is sudden, called mutation, and its magnetic flux density is as high as several Tesla.
电流互感器二次开路的后果
consequence
这种情况后出现后，会产生一下后果：
After this situation occurs, it will have the following consequences:
1. 二次产生数千伏电压（这个没有验证过，是照抄的理论），高电压可能击穿电流互感器的绝缘，使整个配电设备外壳带电，也可能让检修人员触电，有生命危险。
1. The secondary generation of thousands of volts (this has not been verified, is copied from the theory), high voltage may break down the insulation of the current transformer, so that the entire distribution equipment housing is charged, and may also allow maintenance personnel to be electrocuted, which is dangerous to life.
2. 铁芯突变饱和会使互感器的铁芯损耗增加，铁芯会发热，损坏互感器。
2. The sudden saturation of the core will increase the core loss of the transformer, and the core will heat up and damage the transformer.
3. 互感器饱铁芯饱和，计量失准，CT比差和角差加大。
3. Transformer core saturation, measurement misalignment, CT specific difference and Angle difference increase.
