GE Multilin B30 Bus Differential System 6-116 ACTUAL VALUES 6.3 METERING66.3METERING 6.3.1 PARALLEL REDUNDANCY PROTOCOL (PRP)The Parallel Redundancy Protocol (PRP) defines a redundancy protocol for high availability in substation automation net-works.PATH: ACTUAL VALUES STATUS PRPTOTAL RECEIVED PORT A is a counter for total messages received (either from DANPs or from SANs) on Port A.TOTAL RECEIVED PORT B is a counter for total messages received (either from DANPs or from SANs) on Port B.TOTAL ERRORS is a counter for total messages received with an error (bad port code, frame length too short).MISMATCHES PORT A is a counter for total messages received with an error on Port A (PRP frame, but port received throughand LAN ID in the frame do not match).MISMATCHES PORT B is a counter for total messages received with an error on Port B (PRP frame, but port received throughand LAN ID in the frame do not match).6.3.2 METERING CONVENTIONSa) UR CONVENTION FOR MEASURING PHASE ANGLESAll phasors calculated by UR-series relays and used for protection, control and metering functions are rotating phasors thatmaintain the correct phase angle relationships with each other at all times.For display and oscillography purposes, all phasor angles in a given relay are referred to an AC input channel pre-selectedby the SETTINGS SYSTEM SETUP POWER SYSTEM FREQUENCY AND PHASE REFERENCE setting. This settingdefines a particular AC signal source to be used as the reference.The relay will first determine if any “Phase VT” bank is indicated in the source. If it is, voltage channel VA of that bank isused as the angle reference. Otherwise, the relay determines if any “Aux VT” bank is indicated; if it is, the auxiliary voltagechannel of that bank is used as the angle reference. If neither of the two conditions is satisfied, then two more steps of thishierarchical procedure to determine the reference signal include “Phase CT” bank and “Ground CT” bank.If the AC signal pre-selected by the relay upon configuration is not measurable, the phase angles are not referenced. Thephase angles are assigned as positive in the leading direction, and are presented as negative in the lagging direction, tomore closely align with power system metering conventions. This is illustrated below. PRPTotal Rx Port A: Range: 0 to 4G, blank if PRP disabledMESSAGE Total Rx Port B: Range: 0 to 4G, blank if PRP disabledMESSAGE Total Errors: Range: 0 to 4G, blank if PRP disabledMESSAGE Mismatches Port A: Range: 0 to 4G, blank if PRP disabledMESSAGE Mismatches Port B: Range: 0 to 4G, blank if PRP disabled
