800mAX线机主可控硅损坏保护电路的改进研究

XHD150B-10型800mAX线机具有主可控硅损坏保护电路,但此电路在2只（不同相上的）或任3只以上主可控硅击穿、短路或误导通时,当按下摄影手闸第1挡时,X线机仍会出现异常瞬间曝光现象,这将导致因电压过高而造成高压部件击穿损坏或因暂态电流过大而造成X线机损坏.为此,必须对原电路进行改进.材料：导线少许.方法：将摄影高压预上闸接触器MAG SW-R的3对常开触点与3组反向并联的主可控硅连接次序对调.结论：改进后不会影响原机正常的摄影曝光工作程序.在任1只或2只以上主可控硅击穿、短路或误导通时,可使该机一开机便可发现主可控硅损坏故障,使保护电路工作,从而保证X线机的安全.

Improvement of main thyristor's protection circuit of XHD150B-10 800mA X-ray machine

Although the type of XHD150B-IO 800mA X-ray machine possesses a damage protection electric circuit for the main thyristors, with the first switch of photographic hand valve pressed, abnormal instant exposure still appears when double (in different phase) or more than three main thyristors are broken through, short-circuited or mis-energized, and consequently the high voltage element or X-ray machine will break down. Therefore the original electric circuit must be improved. Material: A few of leads. Method: We exchange the conjunction sequence of three NO (normal open) contacting points of radiograph high voltage preparing work relay--MAG SW- R with three reverse parallel connection of main thyristors. Conclusion: The normal procedure of radiographic exposure won't be disturbed after the improvement. When whichever one or more than two main thyristors is broken through, short-circuited or mis-energized, the spoilage can be detected instantly and the protection circuit works correspondingly, which guarantees the safety of X-ray machine.