4.14
SEL-751A Relay Instruction Manual Date Code 20100129
Protection and Logic Functions
Basic Protection
The neutral time-overcurrent elements, 51N1T and 51N2T, respond to neutral
channel current IN as shown Figure 4.6.
Figure 4.6 Neutral Time-Overcurrent Elements 51N1T and 51N2T
MIN RESPONSE TIM 0.00–1.00 51N2MR := 0.00
TOC TRQ CONTROL SEL
OGIC 51N2TC := 1
a
For I
NOM
= 5 A.
b
For I
NOM
= 1 A.
c
For I
NOM
= 2.5 mA.
d
For I
NOM
= 50 mA.
e
For 51_C := U_ .
f
For 51_C := C_.
Table 4.12 Residual Time-Overcurrent Settings (Sheet 1 of 2)
Setting Prompt Setting Range
Setting Name :=
Factory Defau lt
TOC TRIP LVL OFF, 0.50–16.00 A
a
,
0.10–3.20 A
b
51G1P := 0.50
51G1P := 0.10
TOC CURVE SEL U1, U2, U3, U4, U5, C1, C2,
C3, C4, C5
51G1C := U3
TOC TIME DIAL 0.50–15.00
c
,
0.05–1.00
d
51G1TD := 1.50
EM RESET DELAY Y, N 51G1RS := N
CONST TIME ADDER 0.00–1.00 sec 51G1CT := 0.00
MIN RESPONSE TIM 0.00–1.00 51G1MR := 0.00
TOC TRQ CONTROL SELOGIC 51G1TC := 1
TOC TRIP LVL OFF, 0.50–16.00 A
a
,
0.10–3.20 A
b
51G2P := 0.50
51G2P := 0.10
Table 4.11 Neutral Time-Overcurrent Settings (Sheet 2 of 2)
Setting Prompt Setting Range
Setting Name :=
Factory Defau lt
51N1P
|IN|
Setting
51N1TC
Torque Control Switch
SELOGIC
Torque Control
Pickup
Curve
Timeout
Reset
51N1P
51N1R
51N1T
51N1TC Torque Control
State Switch Position
Logical 1 Closed
Logical 0 Open
Setting
51N1RS = Reset Timing
Y Electromechanical
N 1 Cycle
Relay
Word
Bits
SELOGIC
Setting
51N1T Neutral
Time-Overcurrent Element
Curve Timing and Reset Timing
Settings
51N1P Pickup
51N1C Curve Type
51N1TD Time Dial
51N1RS Electromechanical
Reset? (Y/N)
51N1CT Const. Time Add.
51N1MR Min. Response
(From Figure 4.1)
Controls the Torque Control Switch
Note: 51N1T element shown above; 51N2T is similar.
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