5-92 B30 Bus Differential System GE Multilin5.4 SYSTEM SETUP 5 SETTINGS5The FREQUENCY AND PHASE REFERENCE setting determines which signal source is used (and hence which AC signal) forphase angle reference. The AC signal used is prioritized based on the AC inputs that are configured for the signal source:phase voltages takes precedence, followed by auxiliary voltage, then phase currents, and finally ground current.For three phase selection, phase A is used for angle referencing ( ), while Clarke transformation of thephase signals is used for frequency metering and tracking ( ) for better performance dur-ing fault, open pole, and VT and CT fail conditions.The phase reference and frequency tracking AC signals are selected based upon the Source configuration, regardless ofwhether or not a particular signal is actually applied to the relay.Phase angle of the reference signal will always display zero degrees and all other phase angles will be relative to this sig-nal. If the pre-selected reference signal is not measurable at a given time, the phase angles are not referenced.The phase angle referencing is done via a phase locked loop, which can synchronize independent UR-series relays if theyhave the same AC signal reference. This results in very precise correlation of phase angle indications between differentUR-series relays.FREQUENCY TRACKING is set to “Disabled” only in unusual circumstances; consult the factory for special variable-frequency applications.The frequency tracking feature functions only when the B30 is in the “Programmed” mode. If the B30 is “Not Pro-grammed”, then metering values are available but can exhibit significant errors.5.4.3 SIGNAL SOURCESPATH: SETTINGS SYSTEM SETUP SIGNAL SOURCES SOURCE 1(6)Identical menus are available for each source. The "SRC 1" text can be replaced by with a user-defined name appropriatefor the associated source.The first letter in the source identifier represents the module slot position. The number directly following this letter repre-sents either the first bank of four channels (1, 2, 3, 4) called “1” or the second bank of four channels (5, 6, 7, 8) called “5” ina particular CT/VT module. Refer to the Introduction to AC sources section at the beginning of this chapter for additionaldetails on this concept.It is possible to select the sum of all CT combinations. The first channel displayed is the CT to which all others will bereferred. For example, the selection “F1+F5” indicates the sum of each phase from channels “F1” and “F5”, scaled towhichever CT has the higher ratio. Selecting “None” hides the associated actual values.The approach used to configure the AC sources consists of several steps; first step is to specify the information about eachCT and VT input. For CT inputs, this is the nominal primary and secondary current. For VTs, this is the connection type,ratio and nominal secondary voltage. Once the inputs have been specified, the configuration for each source is entered,including specifying which CTs will be summed together. SOURCE 1SOURCE 1 NAME:SRC 1Range: up to six alphanumeric charactersMESSAGE SOURCE 1 PHASE CT:NoneRange: None, F1, F5, F1+F5,... up to a combination ofany 6 CTs. Only Phase CT inputs are displayed.MESSAGE SOURCE 1 GROUND CT:NoneRange: None, F1, F5, F1+F5,... up to a combination ofany 6 CTs. Only Ground CT inputs are displayed.MESSAGE SOURCE 1 PHASE VT:NoneRange: None, F5, L5, S5Only phase voltage inputs will be displayed.MESSAGE SOURCE 1 AUX VT:NoneRange: None, F5, L5, S5Only auxiliary voltage inputs will be displayed.VANGLE REF V A=VFREQUENCY 2V A V B– V C–( ) 3⁄=NOTENOTE
