In a large channel-type electromagnetic loop network

the power flow of transmission lines is in general high. Should tripping of high voltage transmission line occur

the result will be a metastasis of power flow to the lower. Hence the risk of chain faults. The main characteristics of the channel-type electromagnetic loop network are summarized. Proceeding from the grid structure

system size and other factors

an open-loop criterion system for channel-type electromagnetic loop network is built

which is based on static stability margin

thermal stability margin

power flow transfer ratio and security and stability control amount. On this basis

the variation coefficient method is used to calculate the index weight in order to get a composite indicator of channel-type electromagnetic loop network judgment. This method is verified using the channel-type electromagnetic loop network in Qinghai grid to show that open-loop criterion for electromagnetic loop network is reasonable and effective.