To protect the power component of electric welding machine,overtension and undertension protection are circuit designed.

为护焊机的功率器件设计了电路。

The causes are presented as follows: packer unloading pressure, formation damage, oil tool plugging, formation voidage, the worst formation physical properties and the effect from vicinage wells.

地污染或工具堵塞;地;地物性极差;邻井影响等。

Moreover, the proposed control system is of some fault diagnosis and protection functions, such as overcurrent, overvoltage-undervoltage, overtemperature and parameter overrun.

同时，该电源控制系统还具有流、、热、参数超限等故障诊断与护功能。