MiCOM P921/P922/P923 - Schneider - error

P92X/EN IN/F22Page 12/12InstallationMiCOM P921/P922/P9237.2 RS485 PortConnections to the RS485 port are made using ring terminals. It is recommended that a 2core screened cable is used with a maximum total length of 1000m or 200nF total cablecapacitance.A typical cable specification would be:− Each core: 16/0.2 mm copper conductors PVC insulated− Nominal size: 0.5 mm 2 per core− Screen: Overall braid, PVC sheathedRefer to chapter P92x/EN CO, paragraph 2.2 for references of RS232/RS485 converters.7.3 Protective Conductor (Earth) ConnectionEvery relay must be connected to the local earth bar using the M4 earth studs in the bottomleft hand corner of the relay case. The minimum recommended wire size is 2.5 mm 2andshould have a ring terminal at the relay end. Due to the limitations of the ring terminal, themaximum wire size that can be used for any of the medium or heavy duty terminals is6.0 mm 2 per wire. If a greater cross-sectional area is required, two parallel connected wires,each terminated in a separate ring terminal at the relay, or a metal earth bar could be used.NOTE:To prevent any possibility of electrolytic action between brass orcopper earth conductors and the rear panel of the relay, precautionsshould be taken to isolate them from one another. This could beachieved in a number of ways, including placing a nickel-plated orinsulating washer between the conductor and the relay case, or usingtinned ring terminals.