Schweitzer Engineering Laboratories SEL-751 - Table 4.2 CT Configuration Settings; Table 4.3 Voltage Configuration Settings

4.4
SEL-751 Relay Instruction Manual Date Code 20170927
Protection and Logic Functions
Group Settings (SET Command)
Enter as many as 16 characters, including letters A–Z (not case sensitive),
numbers 0–9, periods (.), dashes (-), and spaces. Suggested identifiers include
the location or number of the protected feeder.
Configuration
Settings
The CT ratio settings configure the relay to accurately scale measured values
and report the primary quantities. Calculate the phase and neutral current CT
ratios by dividing the primary rating by the secondary rating.
EXAMPLE 4.1 Phase CT Ratio Setting Calculation
Consider an application where the phase CT rating is 100:5 A.
Set CTR := 100/5 := 20.
Table 4.3 shows the voltage settings. The voltage configuration settings con-
figure the relay voltage inputs to correctly measure and scale the voltage sig-
nals. The relay can be ordered with different secondary voltage input
configurations—standard voltage inputs rated for 300 Vac or LEA voltage
inputs rated for 8 Vac. Refer to Figure 2.21 for different voltage connections.
The voltage configuration settings configure the relay voltage inputs to cor-
rectly measure and scale the voltage signals. The relay can be ordered with
different secondary voltage input configurations—standard voltage inputs
rated for 300 Vac or LEA voltage inputs rated for 8 Vac. Refer to Figure 2.21
for different voltage connections.
The PTR and PTRS settings are applicable and available for setting when the
relay is ordered with standard voltage inputs (300 Vac). The LEA_R,
LEA_SC, LEA_S_R, and LEA_S_SC settings are applicable to the relay with
LEA inputs (8 Vac). The LEA_R and LEA_S_R settings are settable while the
LEA_SC and LEA_S_SC settings are autocalculated by the relay and not
Table 4.2 CT Configuration Settings
Setting Prompt Setting Range
Setting Name :=
Fac to ry Defa ult
PHASE CT RATIO 1–5000 CTR := 120
NEUTRAL CT RATIO 1–5000 CTRN := 120
Table 4.3 Voltage Configuration Settings
Setting Prompt Setting Range
Setting Name :=
Fac to ry Defa ult
PHASE PT RATIO 1.00–10000.00 PTR := 180.00
PHASE LEA RATIO 37.50–500000.00 LEA_R := 180.00
PHASE LEA SCALE 1.00–13333.33
a
a
Autocalculated.
LEA_SC := 4.80
SYNCV PT RATIO 1.00–10000.00 PTRS := 180.00
SYNCV LEA RATIO 37.50–500000.00 LEA_S_R := 180.00
SYNCV LEA SCALE 1.00–13333.33
a
LEA_S_SC := 4.80
XFMR CONNECTION WYE, DELTA DELTA_Y := DELTA
VS CONNECTION VS, 3V0 VSCONN := VS
LINE VOLTAGE OFF, 20.00–250.00 V
b
b
The line voltage setting range is 20.00–480.00 if DELTA_Y := WYE.
VNOM := 120.00
SINGLE V INPUT Y, N SINGLEV := N