列车主电流监测记录装置由主电路电流传感器和监控主机两部分组成。其中电流传感器采用LEM的LT 4000-S型，量程范围可达6000A，额定有效值为4000A，原次边电流变比为1:5000。监控主机由采样电路、CPU、大容量Flash、显示、报警和电源等模块电路组成，主要负责对经过电流传感器变换之后的列车主电流进行采集、判断和记录，同时提供必要的数据上传、显示和报警功能。      电流传感器的输出信号进入监控主机内，经采样滤波隔离测量后，监控主机对超过正常阀值的数据进行触发操作。       

    本装置在正常工作时，实时采样监测主电流电流变化，并将采集到的数据缓存到内部存储器中。一旦发现主电流值超过所设置的阈值（峰值超过设定值保持一定时间或者是电流变化超过设定值，这些参数都可以通过上位机进行修改），系统会将该时刻前后特定时间段内的持续测量数据记录下来，并将缓存中的数据转存到大容量的Flash中，以供日常维护人员下载后在上位机软件进行连续波形显示和分析。当电流变化达到报警阈值时，系统会触发警报，提醒列车工作人员进行检修。

        The main current monitoring and recording device of the train is composed of two parts, the main circuit current sensor and the monitor host. Current sensor use the LEM of LT 4000-S, the range can be 6000A and rated effective value is 4000A, the original secondary side current ratio is 1:5000. Monitoring host is composed of the sampling circuit, CPU, Flash, display, alarm and power supply module circuit, the main responsibility is to collect, judge and record the train main current after the transformation of the current sensor, and provide the necessary data upload, display and alarm. 

        The output signal of the current sensor is transmitted into the monitoring host, when after sampling filter isolation measure, the monitor host will do triggering action to the over normal threshold data. 

       When the device is in normal operation, it monitors the change of main current in real time and caches the collected data into the internal memory. Once the main current value exceeds the set threshold(the peak value is over the setting value and maintains for a certain period of time or the change of the current exceeds the set value, and these parameters can be modified by the host computer), the system will record the continuous measurement data in a specific time period and cache the data stored in the buffer to the large capacity Flash, in order to provide a continuous wave display and analysis of the upper computer software after downloading. When the current change comes to the alarm threshold, the system will trigger the alarm to remind the train staff to carry out inspection.