5-138 L90 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL
SYSTEM SETUP CHAPTER 5: SETTINGS
5
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)
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}
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
PHASE VT F5
CONNECTION
made to the system as “Wye” or “Delta.” An open-delta source VT connection is entered as “Delta.”
5.5.2 Power system
SETTINGS SYSTEM SETUP POWER SYSTEM
VOLTAGE BANK F5
PHASE VT F5
CONNECTION: Wye
Range: Wye, Delta
PHASE VT F5
SECONDARY: 66.4 V
Range: 25.0 to 240.0 V in steps of 0.1
PHASE VT F5
RATIO: 1.00 :1
Range: 1.00 to 24000.00 in steps of 0.01
AUXILIARY VT F5
CONNECTION: Vag
Range: Vn, Vag, Vbg, Vcg, Vab, Vbc, Vca
AUXILIARY VT F5
SECONDARY: 66.4 V
Range: 25.0 to 240.0 V in steps of 0.1
AUXILIARY VT F5
RATIO: 1.00 :1
Range: 1.00 to 24000.00 in steps of 0.01
The nominal PHASE VT F5 SECONDARY voltage setting is the voltage across the relay input terminals when 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 / = 66.4.
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.
POWER SYSTEM
NOMINAL FREQUENCY:
60 Hz
Range: 25 to 60 Hz in steps of 1
PHASE ROTATION:
ABC
Range: ABC, ACB
FREQUENCY AND PHASE
REFERENCE: SRC 1
Range: SRC 1, SRC 2, SRC 3, SRC 4
FREQUENCYTRACKING:
Enabled
Range: Disabled, Enabled
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