Sel 751A - Table 4.10 Negative-Sequence Time-Overcurrent Settings; Figure 4.4 Maximum Phase Time-Overcurrent Elements 51 P1 T and 51 P2 T

4.12
SEL-751A Relay Instruction Manual Date Code 20100129
Protection and Logic Functions
Basic Protection
The maximum phase time-overcurrent elements, 51P1T and 51P2T, respond
to the highest of A, B, and C phase currents as shown Figure 4.4.
Figure 4.4 Maximum Phase Time-Overcurrent Elements 51P1T and 51P2T
The negative-sequence time-overcurrent element 51QT responds to the 3I2
current as shown Figure 4.5.
Table 4.10 Negative-Sequence Time-Overcurrent Settings
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
a
For I
NOM
= 5 A.
b
For I
NOM
= 1 A.
51QP := 6.00
51QP := 1.2
TOC CURVE SEL U1, U2, U3, U4, U5, C1, C2,
C3, C4, C5
51QC := U3
TOC TIME DIAL 0.50–15.00
c
,
0.05–1.00
d
c
For 51_C := U_ .
d
For 51_C := C_.
51QTD := 3.00
EM RESET DELAY Y, N 51QRS := N
CONST TIME ADDER 0.00–1.00 sec 51QCT := 0.00
MIN RESPONSE TIM 0.00–1.00 51QMR := 0.00
TOC TRQ CONTROL SEL
OGIC 51QTC := 1
51P1P
|IP|
Setting
51P1TC
Torque Control Switch
SELOGIC
Torque Control
Pickup
Curve
Timeout
Reset
51P1P
51P1R
51P1T
51P1TC Torque Control
State Switch Position
Logical 1 Closed
Logical 0 Open
Setting
51P1RS = Reset Timing
Y Electromechanical
N 1 Cycle
Relay
Word
Bits
SELOGIC
Setting
51P1T Phase
Time-Overcurrent Element
Curve Timing and Reset Timing
Settings
51P1P Pickup
51P1C Curve Type
51P1TD Time Dial
51P1RS Electromechanical
Reset? (Y/N)
51P1CT Const. Time Add.
51P1MR Min. Response
(From Figure 4.1)
Controls the Torque Control Switch
Note: 51P1T element shown above; 51P2T is similar.