ABB 塑壳断路器附件，外置中性线电流互感器 CT EXT NEUTRAL 63A XT2；
电流互感器的作用：
The function of current transformer:
将一次回路的高电压和大电流变为二次回路标准的低电压和小电流，使测量仪表和保护装置标准化、小型化，并使其结构轻巧、价格便宜，并便于屏内安装。
The low voltage and small current of the high voltage and large current of the first circuit into the standard of the two circuit, make the measuring instrument and protection device standardized and miniaturized, and make its structure light, cheap, and easy to install in the screen.
隔离高压电路。互感器一次侧和二次侧没有电的联系，只有磁的联系。使二次设备与高电压部分隔离，且互感器二次侧均接地，从而保证了设备和人身的安全.
Isolation high voltage circuit. There is no electrical connection between the primary side and the two side of the transformer, only magnetic connection. The two equipment is isolated from the high voltage part, and the two sides of the transformer are grounded, so as to ensure the safety of the equipment and the human body.
互感器在线路中二次侧（接电流表的那一边）是绝对不允许开路的（断开接线），否则有可能会因为二次侧的高电压而发生危险或事故。
The two side of the transformer in the line (the side of the ammeter) is absolutely not allowed to open the road (disconnected wiring), otherwise it may be dangerous or accident because of the high voltage of the two side.