引言电力变压器是电力系统和厂矿企业的心脏,变压器的保护在电力系统中十分重要,我国一向延用传统的继电器保护装置,实践证明存在很多缺陷。因该装置使用大量的有触点继电器元件,使接线复杂、整定困难、容易误动或拒动、可靠性较差、且维修和校验工作量大,因而远远落后于当今科学技术发展的要求。随着计算机技术的飞速发展,采用微电子技术的可编程序控制器,是当前工业控制的主要手段和重要的基础设备之一。可编程序控制器的使用大大简化了控制电路,其编程简单、操作方便、功能完备,可以完成逻辑、顺序、定时、 Introduction Power transformers are the heart of power systems and factories and mines. The protection of transformers is very important in the power system. Our country has always been using traditional relay protection devices. Practice has proved that there are many shortcomings. Because the device uses a large number of contact relay components, the wiring is complex, difficult to set, easy to move or refuse to move, poor reliability, and maintenance and calibration workload, which lags far behind the development of today’s science and technology Claim. With the rapid development of computer technology, the programmable logic controller using microelectronic technology is one of the most important industrial equipment and important infrastructure equipment. The use of programmable logic controller greatly simplifies the control circuit, the programming is simple, easy to operate, fully functional, can complete the logic, sequence, timing,