3-26 L90 Line Current Differential System GE Multilin3.3 PILOT CHANNEL COMMUNICATIONS 3 HARDWARE3The current differential function must be “Enabled” for the communications module to properly operate.Refer to SETTINGS GROUPED ELEMENTS LINE DIFFERENTIAL CURRENT DIFFERENTIAL menu.The fiber optic modules (7A to 7W) are designed for back-to-back connections of UR-series relays only. Forconnections to higher-order systems, use the 72 to 77 modules or the 2A and 2B modules.OBSERVING ANY FIBER TRANSMITTER OUTPUT MAY CAUSE INJURY TO THE EYE.3.3.2 FIBER: LED AND ELED TRANSMITTERSThe following figure shows the configuration for the 7A, 7B, 7C, 7H, 7I, and 7J fiber-only modules.Figure 3–27: LED AND ELED FIBER MODULES3.3.3 FIBER-LASER TRANSMITTERSThe following figure shows the configuration for the 72, 73, 7D, and 7K fiber-laser module.Figure 3–28: LASER FIBER MODULESWhen using a laser Interface, attenuators can be necessary to ensure that you do not exceed themaximum optical input power to the receiver.NOTENOTE
