# Power System - GE L90 Instruction Manual

Line current differential system.

SYSTEM SETUP
The same rule applies for current sums from CTs with different secondary taps (5 A and 1 A).
5.5.1.2 Voltage banks
SETTINGS  SYSTEM SETUP  AC INPUTS  VOLTAGE BANK F5(L5)
 VOLTAGE BANK F5
Because energy parameters are accumulated, these values should be recorded and then reset immediately prior to
changing VT characteristics.
Two banks of phase/auxiliary VTs can be set, where voltage banks are denoted in the following format (X represents the
module slot position letter):
Xa, where X = {F, L} and a = {5}
5
See the Introduction to AC Sources section at the beginning of this chapter for details.
With VTs installed, the relay can perform voltage measurements as well as power calculations. Enter the
made to the system as "Wye" or "Delta." An open-delta source VT connection is entered as "Delta."
CONNECTION
The nominal
voltage 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
connection, the secondary voltage is 115; that is, (13800 / 14400) × 120. For a wye connection, the voltage value
entered must be the phase to neutral voltage, which is 115 /
On a 14.4 kV system with a delta connection and a VT primary to secondary turns ratio of 14400:120, the voltage
value entered is 120; that is, 14400 / 120.

## 5.5.2 Power system

SETTINGS  SYSTEM SETUP  POWER SYSTEM
 POWER SYSTEM
5-122
PHASE VT F5
CONNECTION: Wye
PHASE VT F5
SECONDARY: 66.4 V
PHASE VT F5
RATIO: 1.00 :1
AUXILIARY VT F5
CONNECTION: Vag
AUXILIARY VT F5
SECONDARY: 66.4 V
AUXILIARY VT F5
RATIO: 1.00 :1
voltage setting is the voltage across the relay input terminals when nominal
PHASE VT F5 SECONDARY
NOMINAL FREQUENCY:
60 Hz
PHASE ROTATION:
ABC
FREQUENCY AND PHASE
REFERENCE: SRC 1
FREQUENCYTRACKING:
Enabled
Range: Wye, Delta
Range: 25.0 to 240.0 V in steps of 0.1
Range: 1.00 to 24000.00 in steps of 0.01
Range: Vn, Vag, Vbg, Vcg, Vab, Vbc, Vca
Range: 25.0 to 240.0 V in steps of 0.1
Range: 1.00 to 24000.00 in steps of 0.01
= 66.4.
Range: 25 to 60 Hz in steps of 1
Range: ABC, ACB
Range: SRC 1, SRC 2, SRC 3, SRC 4
Range: Disabled, Enabled
L90 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL
CHAPTER 5: SETTINGS
PHASE VT F5