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

为保护焊机的功率器件过压欠压路。

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;地欠压;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，该制系统还具有过流、过欠压、过热、参数超限等故障诊断与保护功能。