Sel SEL-351S - Table 9.8 Main Relay Functions that Change with VSCONN, When PTCONN = WYE

9.51
Date Code 20080103 Instruction Manual SEL-351S Relay
Setting the Relay
Settings Explanations
voltage input VS-NS is used in certain relay elements, as shown in Ta ble 9.8
and Table 9.9. When VSCONN = 3V0, some relay elements are unavailable
or cannot be selected. This Instruction Manual explains these differences in
relation to each affected element or setting. To indicate the state of VSCONN
in SEL
OGIC control equations, Relay Word bit 3V0 operates as shown in
Figure 9.21.
Refer to Relay Settings (Serial Port Command SET and Front Panel) on
page SET.1.
VNOM = 67.00 V secondary (when PTCONN = WYE) or 116.05 V
secondary (when PTCONN = DELTA) is the factory default value. See
Potential Transformer Ratios and PT Nominal Secondary Voltage Settings on
page 9.53 for details on using VNOM with numeric setting values.
VNOM = OFF, if selected, causes several relay elements and functions to be
disabled or nonselectable, as shown in Table 9.10. The relay interprets setting
VNOM = OFF as indicating that valid three-phase voltages are not connected
to relay terminals VA, VB, VC, and N. See Figure 2.30 for an example
application that uses VNOM = OFF. This selection is intended to allow the
remaining relay features to be used with just one phase voltage connected,
without any of the sequence-voltage-based elements misoperating because of
erroneous quantities.
Table 9.8 Main Relay Functions That Change With VSCONN, When
PTCONN = WYE
Relay Function When VSCONN=VS When VSCONN=3V0
Zero-sequence voltage-polarized
ground directional elements (ORDER
setting choices “V”, “S”, and “U”)
Uses 3V
0
calculated
from V
A
, V
B
, V
C
.
Uses V
S
·(PTRS/PTR)
as 3V
0
a
.
a
The PTRS/PTR adjustment brings the broken-delta 3V
0
quantity to the same base voltage as
the relay impedance settings, which are based on the V
A
, V
B
, V
C
voltage base.
Wattmetric and incremental
conductance elements (ORDER setting
choice “P”).
Uses 3V
0
calculated
from V
A
, V
B
, V
C
Uses V
S
·(PTRS/PTR)
as 3V
0
a
.
Synchronism check elements Available Not available
Three-phase power elements
(EPWR = 3P1–3P4). See
Power Elements (Available in Firmware
Version 7) on page 3.59.
No difference
Uses a three-phase power formula, including
3V
0
calculated from V
A
, V
B
, V
C
.
Three-phase power metering
(MW3P, MVAR3P, etc.)
No difference
Uses the sum of the single-phase power
calculations from V
A
, V
B
, V
C
, I
A
, I
B
, I
C
(primary values).
Quantity “3V0” in Metering,
Fast Meter, Load Profile Recorder
(LDP), and Distributed Network
Protocol (DNP).
No difference
Uses 3V
0
calculated from V
A
, V
B
, V
C
(primary value).
Quantity “VS” in Metering,
Fast Meter, Load Profile, and DNP.
No difference
Uses V
S
as VS (primary value).