Based on the fault analysis of retard grid R3 and R4, the grid was scrapped due to contactor tip quality and improper tip installation.

• 根据HW0406号制动电阻栅R3和R4电阻的故障原因分析，电阻栅烧毁以及报废由于接触器触头的质量、触头安装方式不正确导致。