1、一次匝数少，二次匝数多

1, one turn is small, the second turns are many 

用于电力系统中的电流互感器，其一次绕组通常是一次设备的进、出导线，只有1匝或2匝;其二次匝数却很多。如：变比为1250/1的电流互感器，其一次为1匝，二次匝数有1250匝。

For the current transformer in the electrical system, the first winding is usually a device in and out of a wire, only one turn or two. The second turn is a lot. For example: a current transformer of 1250/1, one turn for one turn, and the second turn for a number of 1250 turns. 

2、铁芯中工作磁密很低，系统故障时磁密大

The iron core is very low in the work, and the system failure is large 

正常运行时，电流互感器铁芯中工作磁密很低，其一次与二次保持安匝平衡。当系统故障时，由于故障电流很大，二次电压很高，励磁电流增大，铁芯中磁密急剧升高，甚至使铁芯饱和。

In normal operation, the working magnet is low in the iron core of the current transformer. When the system fails, the secondary voltage is very high due to the fault current, the excitation current increases, the magnetightness of the iron core rises sharply, even the core saturates. 

3、高内阻，电流源

High internal resistance, current source 

正常工况下，铁芯中的磁密很低，励磁阻抗很大，而二次匝数很多。从二次侧看进去，其阻抗很大。负载阻抗与电流互感器的内阻相比，可以忽略不计，故负载阻抗的变化对二次电流的影响不大，可称之为电流源。

Under normal working conditions, the magnetic tightness in the iron core is very low, the excitation impedance is very large, and the second turn is a lot. From the second side, the impedance is large. The load impedance is negligible compared with the internal resistance of current transformer, so the change of load impedance is not very important to secondary current, which can be called current source. 

4、需要二次负载小(相对电压互感器)

Need secondary load (relative voltage transformer) 

电流互感器的二次负责如果很大，运行时其二次电压很高，励磁电流必然增大，从而使电流变换的误差增大。特别是在系统故障时，电流互感器一次电流可能达额定电流的数十倍，致使铁芯饱和，电流变换误差很大，不满足继电保护的要求，甚至使保护误动。

The secondary responsibility of the current transformer is large, the second voltage is high, the excitation current must increase, and the error of the current transformation increases. Especially when system failure, current transformer primary current may amount to tens of times the rated current, the iron core saturation, current transformation error is very big, do not meet the requirements of relay protection, and even make the protection misoperation. 

5、二次回路不得开路

The second circuit shall not be opened 

电流互感器的二次回路不得开路。如果在运行中二次回路开路，二次电流消失，去磁作用也随之消失，铁芯中的磁密很高;又由于二次匝数特多，二次电压会很高，有时可达数千伏，危及二次设备及人身安全。

The secondary circuit of current transformer may not be opened. If the second circuit starts off in the running loop, the secondary current disappears, the demagnetizing effect disappears, and the magnetic density of the iron core is high. Due to the number of secondary turns, the secondary voltage can be high, sometimes up to a thousand volts, endangering secondary equipment and personal safety.