Schweitzer Engineering Laboratories SEL-751 - Table 4.42 Synchronism-Check Settings

4.108
SEL-751 Relay Instruction Manual Date Code 20170927
Protection and Logic Functions
Group Settings (SET Command)
Voltage Input VS Connected Phase-to-Phase or Beyond Delta-Wye Transformer
Sometimes synchronism-check voltage VS cannot be in phase with voltage
VA, VB, or VC (wye connected PTs) or VAB, VBC, or VCA (delta-connected
PTs). This happens in applications where voltage input VS is connected
➤ Phase-to-phase when using a wye-connected relay
➤ Phase-to-neutral when using a delta-connected relay
➤ Beyond a delta-wye transformer
For such applications requiring VS to be at a constant phase angle difference
from any of the possible synchronizing voltages (VA, VB, or VC; VAB, VBC,
or VCA), an angle setting is made with the SYNCPH setting (see Table 4.42
and Setting SYNCPH on page 4.108).
Setting SYNCPH
Enable the two single-phase synchronism-check elements by setting E25 := Y.
Wye-Connected Voltages
The angle setting choices (0, 30, …, 300, or 330 degrees) for setting SYNCPH
are referenced to VA, and they indicate how many degrees VS constantly lags
VA. In this case, voltage input VA-N has to be connected and has to meet the
“healthy voltage” criteria (settings 25VHI and 25VLO—see Figure 4.68). For
situations where VS cannot be in phase with VA, VB, or VC, the angle setting
choices (0, 30, …, 300, or 330 degrees) are referenced to VA.
Delta-Connected Voltages
The angle setting choices (0, 30, …, 300, or 330 degrees) for setting SYNCPH
are referenced to VAB, and they indicate how many degrees VS constantly
lags VAB. In this application, voltage input VA-VB has to be connected and has
Table 4.42 Synchronism-Check Settings
Setting Prompt Setting Range
Setting Name :=
Fac to ry Defa ult
SYNCH CHECK Y, N E25 := N
VS WINDOW LOW 0.00–300.00 V 25VLO := 105.00
VS WINDOW HIGH 0.00–300.00 V 25VHI := 130.00
V RATIO COR FAC 0.50–2.00 25RCF := 1.00
MAX SLIP FREQ 0.05–0.50 Hz 25SF := 0.20
MAX ANGLE 1 0–80 deg 25ANG1 := 25
MAX ANGLE 2 0–80 deg 25ANG2 := 40
SYNCH PHASE VA, VB, VC, or 0, 30, 60, 90, 120,
150, 180, 210, 240, 270, 300, 330
deg lag VA
a
a
Range shown for DELTA_Y := WYE.
SYNCPH := VA
SYNCH PHASE VAB, VBC, VCA, or 0, 30, 60, 90,
120, 150, 180, 210, 240, 270, 300,
330 deg lag VAB
b
b
Range shown for DELTA_Y := DELTA.
SYNCPH := VAB
BRKR CLOSE TIME OFF, 1-1000 ms TCLOSD := 50
BLK SYNCH CHECK SV BSYNCH := 52A
NOTE: The synchronism-check
element is only available when
VSCONN := VS.
NOTE: Settings SYNCPH := 0 and
SYNCPH := VA are effectively the
same (voltage VS is directly
synchronism checked with voltage
VA; VS does not lag VA). The relay
displays the setting entered (SYNCPH
:= VA or SYNCPH := 0).