GE C70 Instruction Manual

Also see for C70: Communications manual Communications guide Instruction manual Instruction manual Instruction manual

Contents

CHAPTER 5: SETTINGS SYSTEM SETUPC70 CAPACITOR BANK PROTECTION AND CONTROL SYSTEM – INSTRUCTION MANUAL 5-1255For three phase selection, phase A is used for angle referencing (VANGLE REF = VA), while Clarke transformation of the phasesignals is used for frequency metering and tracking (V FREQUENCY = (2VA - V B - VC) / 3) for better performance during 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 always displays zero degrees and all other phase angles are relative to this signal. If thepre-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 different UR-series relays.FREQUENCY TRACKING is set to “Disabled” only in unusual circumstances; consult GE Grid Solutions for special variable-frequency applications.5.5.3 Signal sourcesSETTINGS  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 letterrepresents 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” in a particular CT/VT module. See the Introduction to AC Sources section at the beginning of this chapter for details.It is possible to select the sum of all CT combinations. The first channel displayed is the CT to which all others are referred.For example, the selection “F1+F5” indicates the sum of each phase from channels “F1” and “F5,” scaled to whichever CThas 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, ratioand nominal secondary voltage. Once the inputs have been specified, the configuration for each source is entered,including specifying which CTs are summed together.5.5.3.1 User selection of AC parameters for comparator elementsCT/VT modules automatically calculate all current and voltage parameters from the available inputs. Users must select thespecific input parameters to be measured by every element in the relevant settings menu. The internal design of theelement specifies which type of parameter to use and provides a setting for source selection. In elements where theparameter can be either fundamental or RMS magnitude, such as phase time overcurrent, two settings are provided. Onesetting specifies the source, the second setting selects between fundamental phasor and RMS.The frequency tracking feature functions only when the C70 is in the “Programmed” mode. If the C70 is “NotProgrammed,” then metering values are available but can exhibit significant errors. SOURCE 1  SOURCE 1 NAME:SRC 1Range: up to 20 alphanumeric characters SOURCE 1 PHASE CT:NoneRange: None, F1,... up to any 6 CTs. Only Phase CTinputs are displayed. SOURCE 1 GROUND CT:NoneRange: None, F1,... up to any 6 CTs. Only Ground CTinputs are displayed. SOURCE 1 PHASE VT:NoneRange: None, F5, M1, M5, U5Only phase voltage inputs are displayed SOURCE 1 AUX VT:NoneRange: None, F5, M1, M5, U5Only auxiliary voltage inputs are displayed