5-62 B30 Bus Differential System GE Multilin5.2 PRODUCT SETUP 5 SETTINGS5Figure 5–13: INTERLOCKING BUS PROTECTION SCHEME VIA DIRECT INPUTS/OUTPUTSIn the above application, the following settings should be applied. For UR-series IED 1:DIRECT OUTPUT DEVICE ID: “1”DIRECT I/O CH1 RING CONFIGURATION: “Yes”DIRECT I/O CH2 RING CONFIGURATION: “Yes”For UR-series IED 2:DIRECT OUTPUT DEVICE ID: “2”DIRECT I/O CH1 RING CONFIGURATION: “Yes”DIRECT I/O CH2 RING CONFIGURATION: “Yes”For UR-series IED 3:DIRECT OUTPUT DEVICE ID: “3”DIRECT I/O CH1 RING CONFIGURATION: “Yes”DIRECT I/O CH2 RING CONFIGURATION: “Yes”For UR-series IED 4:DIRECT OUTPUT DEVICE ID: “4”DIRECT I/O CH1 RING CONFIGURATION: “Yes”DIRECT I/O CH2 RING CONFIGURATION: “Yes”Message delivery time is approximately 0.2 of power system cycle (at 128 kbps) times number of ‘bridges’ between the ori-gin and destination. Dual-ring configuration effectively reduces the maximum ‘communications distance’ by a factor of two.In this configuration the following delivery times are expected (at 128 kbps) if both rings are healthy:IED 1 to IED 2: 0.2 of power system cycle;IED 1 to IED 3: 0.4 of power system cycle;IED 1 to IED 4: 0.2 of power system cycle;IED 2 to IED 3: 0.2 of power system cycle;IED 2 to IED 4: 0.4 of power system cycle;IED 3 to IED 4: 0.2 of power system cycle.If one ring is broken (say TX2-RX2) the delivery times are as follows:IED 1 to IED 2: 0.2 of power system cycle;IED 1 to IED 3: 0.4 of power system cycle;IED 1 to IED 4: 0.6 of power system cycle;IED 2 to IED 3: 0.2 of power system cycle;IED 2 to IED 4: 0.4 of power system cycle;IED 3 to IED 4: 0.2 of power system cycle.A coordinating timer for this bus protection scheme could be selected to cover the worst case scenario (0.4 of a power sys-tem cycle). Upon detecting a broken ring, the coordination time should be adaptively increased to 0.6 of a power systemcycle. The complete application requires addressing a number of issues such as failure of both the communications rings,failure or out-of-service conditions of one of the relays, etc. Self-monitoring flags of the direct inputs and outputs featurewould be primarily used to address these concerns.842716A1.CDRUR IED 1RX1TX2TX1RX2UR IED 2TX2RX2RX1TX1UR IED 4TX1RX1RX2TX2UR IED 3RX2TX1TX2RX1
