GE Power ManagementL90 Line Differential Relay5-255 SETTINGS 5.3 SYSTEM SETUP5b) VOLTAGE BANKSPATH: SETTINGS ÖØ SYSTEM SETUP Ö AC INPUTS ÖØ VOLTAGE BANK X1‘X’ = F, M, or U. ‘F’, ‘M’, and ‘U’ are module slot position letters. See also the INTRODUCTION TO AC SOURCES section.Up to 3 banks of phase/auxiliary VTs can be set.With VTs installed, the relay can be used to perform voltage measurements as well as power calculations. Enter the PHASEVT xx CONNECTION made to the system as "Wye" or "Delta". An open-delta source VT connection would be entered as"Delta". See the typical wiring diagram in the HARDWARE chapter for details.The nominal Phase VT Secondary Voltage setting is the voltage across the relay input terminals when nominal volt-age is applied to the VT primary.For example, on a system with a 13.8 kV nominal primary voltage and with a 14400:120 Volt VT in a Delta connec-tion, the secondary voltage would be 115, i.e. (13800 / 14400) × 120. For a Wye connection, the voltage valueentered must be the phase to neutral voltage which would be 115 / = 66.4.On a 14.4 kV system with a Delta connection and a VT primary to secondary turns ratio of 14400:120, the voltagevalue entered would be 120, i.e. 14400 / 120.5.3.2 POWER SYSTEMPATH: SETTINGS ÖØ SYSTEM SETUP ÖØ POWER SYSTEMThe power system NOMINAL FREQUENCY value is used as a default to set the digital sampling rate if the system frequencycannot be measured from available signals. This may happen if the signals are not present or are heavily distorted. Beforereverting to the nominal frequency, the frequency tracking algorithm holds the last valid frequency measurement for a safeperiod of time while waiting for the signals to reappear or for the distortions to decay.The phase sequence of the power system is required to properly calculate sequence components and power parameters.The PHASE ROTATION setting matches the power system phase sequence. Note that this setting informs the relay of theactual system phase sequence, either ABC or ACB. CT and VT inputs on the relay, labeled as A, B, and C, must be con-nected to system phases A, B, and C for correct operation. VOLTAGE BANK X5PHASE VT X5CONNECTION: WyeRange: Wye, DeltaMESSAGE PHASE VT X5SECONDARY: 66.4 VRange: 50.0 to 240.0 V in steps of 0.1MESSAGE PHASE VT X5RATIO: 1.00 :1Range: 1.00 to 24000.00 in steps of 1.00MESSAGE AUXILIARY VT X5CONNECTION: VagRange: Vn, Vag, Vbg, Vcg, Vab, Vbc, VcaMESSAGE AUXILIARY VT X5SECONDARY: 66.4 VRange: 50.0 to 240.0 V in steps of 0.1MESSAGE AUXILIARY VT X5RATIO: 1.00 :1Range: 1.00 to 24000.00 in steps of 1.00 POWER SYSTEMNOMINAL FREQUENCY:60 HzRange: 25 to 60 Hz in steps of 1MESSAGE PHASE ROTATION:ABCRange: ABC, ACBMESSAGE FREQUENCY AND PHASEREFERENCE: SRC 1Range: SRC 1, SRC 2,..., SRC 6MESSAGE FREQUENCY TRACKING:EnabledRange: Disabled, EnabledNOTE3
