4.42
SEL-787 Relay Instruction Manual Date Code 20150130
Protection and Logic Functions
Basic Protection
The neutral overcurrent and time-overcurrent elements, 50N11T, 50N12T, and
51N1T, respond to neutral channel current IN1 as shown in Figure 4.19 and
Figure 4.24.
Figure 4.24 Neutral Time-Overcurrent Elements 51N1T and 51N2T
Relay Word Bit ORED51T
Relay Word bit ORED51T is asserted if any of the relay word bits 51P1T,
51P2T, 51G1T, 51G2T, 51Q1T, 51Q2T, OR 51N1T are asserted.
NEUT IOC DELAY 0.00–5.00 sec 50N12D := 0.50
NEUT IOC TRQCTRL SEL
OGIC 50N12TC := 1
a
For I
NOM
=5 A.
b
For I
NOM
=1 A.
Table 4.15 Neutral Time-Overcurrent Settings
Setting Prompt Setting Range
Setting Name :=
Fac tory Default
NEUT 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.
51N1P := OFF
NEUT TOC CURVE U1, U2, U3, U4, U5,
C1, C2, C3, C4, C5
51N1C := U3
NEUT TOC TDIAL 0.50–15.00
c
0.05–1.00
d
c
For 51_C := U_.
d
For 51_C := C_.
51N1TD := 1.50
EM RESET DELAY Y, N 51N1RS := N
CONST TIME ADDER 0.00–1.00 sec 51N1CT := 0.00
MIN RESPONSE TIM 0.00–1.00 sec 51N1MR := 0.00
NEUT TOC TRQCTRL SEL
OGIC 51N1TC := 1
Table 4.14 Neutral Overcurrent Settings (Sheet 2 of 2)
Setting Prompt Setting Range
Setting Name :=
Fac tory Default
51N1P
|IN1|
Setting
51N1TC
Torque Control Switch
SEL
OGIC
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
(From Figure 4.14)
51N1T Neutral
Time-Overcurrent Element
Curve Timing and Reset Timing
51N1P Pickup
51N1C Curve Type
51N1TD Time Dial
51N1RS Electromechanical
Reset? (Y/N)
51N1CT Const. Time Add.
51N1MR Min. Response
Settings
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