This paper has summed up and compared the differences in technology between the microcomputer protections and the old routine protections

and pointed out the principles of the protection arrangment in the power network

bused on the practice of design

test and operation in the all systems of our province and through out the country. Two chief problems

i. e. the coordination of two reclosures and the interface of switching the high-frequency protections to the by-pass bus

have been analyzed and discussed deeply. At last

the auther expressed the opinion upon the application of the microcomputer protections.