Schweitzer Engineering Laboratories SEL-787 - Figure 4.16 Residual Time-Overcurrent Elements 51 G1 T and 51 G2 T; Table 4.11 Winding N Negative-Sequence Time-Overcurrent Settings (N = 1, 2)

4.35
Date Code 20081022 Instruction Manual SEL-787 Relay
Protection and Logic Functions
Basic Protection
The residual time-overcurrent elements, 51G1T and 51G2T, respond to
residual currents IGW1 and IGW2 as shown Figure 4.16.
Figure 4.16 Residual Time-Overcurrent Elements 51G1T and 51G2T
The negative-sequence time-overcurrent element 51QnT responds to the 3I2
current as shown Figure 4.17.
Table 4.11 Winding n Negative-Sequence Time-Overcurrent Settings
(n = 1, 2)
Setting Prompt Setting Range
Setting Name :=
Facto ry Defa ul t
NSEQ TOC LEVEL OFF, 0.50–16.00 A
a
,
0.10–3.20 A
b
a
For I
NOM
=5 A.
b
For I
NOM
=1 A.
51QnP :=OFF
51QnP := OFF
NSEQ TOC CURVE U1, U2, U3, U4, U5, C1, C2,
C3, C4, C5
51QnC := U3
NSEQ TOC TDIAL 0.50–15.00
c
,
0.05–1.00
d
c
For 5 1_ C := U_.
d
For 5 1_ C := C_ .
51QnTD := 3.00
EM RESET DELAY Y, N 51QnRS := N
CONST TIME ADDER 0.00–1.00 sec 51QnCT := 0.00
MIN RESPONSE TIM 0.00–1.00 sec 51QnMR := 0.00
NSEQ TOC TRQCTRL SELOGIC 51QnTC := 1
51GnP
|IGWn|
Setting
51GnTC
Torque Control Switch
SEL
OGIC
Torque Control
Pickup
Curve
Timeout
Reset
51GnP
51GnR
51GnT
51GnTC Torque Control
State Switch Position
Logical 1 Closed
Logical 0 Open
Setting
51GnRS = Reset Timing
Y Electromechanical
N 1 Cycle
Relay
Word
Bits
SELOGIC
Setting
(From Figure 4.14)
Note: 51G1T element shown above; 51G2T is similar.
51G1T Residual
Time-Overcurrent Element
Curve Timing and Reset Timing
51GnP Pickup
51GnC Curve Type
51GnTD Time Dial
51GnRS Electromechanical
Reset? (Y/N)
51GnCT Const. Time Add.
51GnMR Min. Response
Settings