Sel 751A - Basic Protection; VNOM Range Check; Overcurrent Elements; Table 4.4 Maximum Phase Overcurrent Settings

4.5
Date Code 20100129 Instruction Manual SEL-751A Relay
Protection and Logic Functions
Basic Protection
VNOM Range Check
The relay performs a range check for the VNOM setting that depends upon the
voltage-input delta or wye configuration. When setting DELTA_Y is DELTA,
then the allowed range of the VNOM is 100–250 V (l-l). When setting
DELTA_Y is WYE, then the allowed range of VNOM is 100–440 V (l-l).
Note that the VNOM setting is always in line-to-line voltage, even when set
for a wye configuration. You should be careful to use a solidly-grounded wye
system for VNOM inputs greater than 250 V (l-l) to avoid a 1.73 increase in
terminal voltages from a line-to-ground fault.
Basic Protection
Overcurrent Elements
Four levels of instantaneous/definite-time elements are available for phase,
neutral, residual, and negative-sequence overcurrent as shown in Table 4.4
through Table 4.7 and in Figure 4.1.
Each element can be torque controlled using appropriate SEL
OGIC control
equations (e.g., when 50P1TC := IN401, the 50P1 element will be operational
only if IN401 is asserted).
Table 4.4 Maximum Phase Overcurrent Settings
Setting Prompt Setting Range
Setting Name :=
Facto ry Defau lt
MAXP OC TRIP LVL OFF, 0.50–100.00 A
a
,
0.10–20.00 A
b
a
For I
NOM
= 5 A.
b
For I
NOM
= 1 A.
50P1P := 10.00
50P1P := 2.00
MAXP OC TRIP DLY 0.00–5.00 sec 50P1D := 0.00
MAXP OC TRQ CON SELOGIC 50P1TC := 1
MAXP OC TRIP LVL OFF, 0.50–100.00 A
a
,
0.10–20.00 A
b
50P2P := 10.00
50P2P := 2.00
MAXP OC TRIP DLY 0.00–5.00 sec 50P2D := 0.00
MAXP OC TRQ CON SELOGIC 50P2TC := 1
MAXP OC TRIP LVL OFF, 0.50–100.00 A
a
,
0.10–20.00 A
b
50P3P := 10.00
50P3P := 2.00
MAXP OC TRIP DLY 0.00–5.00 sec 50P3D := 0.00
MAXP OC TRQ CON SEL
OGIC 50P3TC := 1
MAXP OC TRIP LVL OFF, 0.50–100.00 A
a
,
0.10–20.00 A
b
50P4P := 10.00
50P4P := 2.00
MAXP OC TRIP DLY 0.00–5.00 sec 50P4D := 0.00
MAXP OC TRQ CON SEL
OGIC 50P4TC := 1