Sel 751A - Overvoltage Function; Table 4.18 Overvoltage Settings

4.30
SEL-751A Relay Instruction Manual Date Code 20100129
Protection and Logic Functions
Voltage-Based Protection
Overvoltage Function
NOTE: The under- and overvoltage
level settings 27P and 59P are in per
unit nominal voltage, Vnm. The relay
automatically calculates Vnm, using
the settings VNOM and DELTA_Y as
follows:
Vnm = VNOM if DELTA_Y := DELTA;
Vnm = VNOM/1.732 if
DELTA_Y := WYE.
The level settings 27S and 59S are in
secondary voltage.
When you connect the SEL-751A voltage inputs to phase-to-phase connected
VTs (single-phase or three-phase), as in Figure 2.17 or Figure 2.18, the relay
provides two levels of phase-to-phase overvoltage and undervoltage elements.
When you connect the SEL-751A voltage inputs to phase-to-neutral
connected VTs (single-phase or three-phase), as in Figure 2.17 or Figure 2.18,
the relay provides two levels of phase-to-neutral overvoltage and undervoltage
elements. When a synchronism voltage input is present (e.g., VS input shown
in Figure 2.18) the SEL-751A provides two levels of VS under- and
overvoltage elements. These elements can be used to control reclosing logic
described later.
Each of the elements has an associated time delay, except the three-phase
under- and overvoltage elements, 3P27 and 3P59. You can use these elements
as you choose for tripping and warning. Figure 4.18 and Figure 4.19 show the
logic diagram for the undervoltage and overvoltage elements, respectively. To
disable any of these elements, set the level settings equal to OFF.
Table 4.18 Overvoltage Settings
Setting Prompt Setting Range
Setting Name :=
Factory Defau lt
OV TRIP1 LEVEL OFF, 0.02–1.20 xVnm 59P1P := 1.10
OV TRIP1 DELAY 0.0–120.0 sec 59P1D := 0.5
OV TRIP2 LEVEL OFF, 0.02–1.20 xVnm 59P2P := OFF
OV TRIP2 DELAY 0.0–120.0 sec 59P2D := 5.0
ZS OV TRIP1 LVL OFF, 0.02-1.20 xVnm 59G1P := OFF
ZS OV TRIP1 DLY 0.0-120.0 sec 59G1D := 0.5
ZS OV TRIP2 LVL OFF, 0.02-1.20 xVnm 59G2P := OFF
ZS OV TRIP2 DLY 0.0-120.0 sec 59G2D := 5.0
NSQ OV TRIP1 LVL OFF, 0.02-1.20 xVnm 59Q1P := OFF
NSQ OV TRIP1 DLY 0.0-120.0 sec 59Q1D := 0.5
NSQ OV TRIP2 LVL OFF, 0.02-1.20 xVnm 59Q2P := OFF
NSQ OV TRIP2 DLY 0.0-120.0 sec 59Q2D := 5.0
OVS LEVEL 1 OFF, 2.00–300.00 V 59S1P := OFF
OVS DELAY 1 0.0–120.0 sec 59S1D := 0.5
OVS LEVEL 2 OFF, 2.00–300.00 V 59S2P := OFF
OVS DELAY 2 0.0–120.0 sec 59S2D := 0.5