定径机传动装置晶闸管经常击穿的解决方法

Solution to Thyristor Frequency Breakdown of Driving Device for Sizing Mill

分析了无缝厂定径机组主传动调速装置晶闸管经常击穿的原因，是国产晶闸管与61LA70的触发电路不匹配，在逆变时晶闸管有时触发不开，造成换相失败产生很大的短路电流使晶闸管击穿。由于定径机不需要频繁正反转和快速停车，通过PLC控制调速装置正、反组脉冲的开通与封锁，使装置不进入逆变状态，避免了逆变失败，解决了晶闸管经常击穿的问题。

Analyze the reasons of the thyristor frequency breakdown for the main drive speed regulation device of sizing mill unit in the seamless steel tube mill. The reason is that domestic thyristor doesn＇ t match with 6RA70 trigger circuit and the thyristor sometimes can＇ t trigger out during reverse change, as the result the short circuit current break down the thyristor caused by phase change failure. As the sizing mill doesn＇ t need frequent forward and reverse rotary, fast stop and PLC control the switch on and blocking of the forward and reverse group pulse for the speed regulating device, which will not enable the device turn into reverse change status, the reverse change failure is avoided, and the problem is solved.