The "ORION" APK-OI (Tx-transmitter, Rx-receiver) are developed for transmission and reception of relay protection (RP) and emergency control schemes (ECS) between power facilities. The terminals have an optical interface and use a dedicated single-mode optical fiber. Data transmission channel formed by terminals is full duplex (WDM).The optical fiber significantly improves the reliability and safety parameters. The terminals set (Tx and Rx) has the ability to automatically switch to a redundant  optical fiber and work in optical channels with multiplexers.