4.160
SEL-700G Relay
Instruction Manual
Date Code 20170814
Protection and Logic Functions
Group Settings (SET Command)
Sometimes the VS voltage cannot be in phase with any one of the voltage
inputs. This happens in applications where voltage input VS is connected
➤
Phase-to-phase when DELTAY_X := WYE
➤
Phase-to-neutral when DELTAY_X := DELTA
➤
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 (VAX, VBX, VCX; or
VABX, VBCX, VCAX), an angle setting is made with the SYNCPX setting.
The angle setting choices (0, 30, …, 300, or 330 degrees) for setting SYNCPX
are referenced to VAX or VABX (for DELTAY_X := WYE or DELTA
respectively), and they indicate how many degrees VS constantly lags the
reference. Use the angle setting in situations where VS cannot be in phase
with one of the voltage inputs.
NOTE:
The settings SYNCPX := 0 and
SYNCPX := VAX or VABX (reference
voltage) are effectively the same
(voltage VS is directly synchronism
checked with the reference; VS does
not lag the reference).
See Figure 4.107 for a few examples of setting SYNCPX. Figure 4.107 (d)
shows a relay wired with delta-connected phase PTs, and a C-phase-to-ground
connected VS input. With ABC rotation, the correct SYNCPX setting for this
example is 270 degrees, the amount that VS (C to Gnd.) lags VABX. See SEL
Application Guide AG2002-02, Compensate for Constant Phase Angle
Difference in Synchronism Check with the SEL-351 Relay Family, for more
information on setting SYNCP with an angle setting. This application guide
was written for the SEL-351, but it is generally applicable to the SEL-700G.
Use the 25VLOX, 25VHIX, 25VDIFX, and GENV+ settings to define the
voltage conditions under which the generator breaker can be closed safely.
The 25VLOX and 25VHIX settings define an acceptable voltage magnitude
window. A close is permitted only if the generator and system voltages are
within this window.
Make the 25VLOX and 25VHIX settings based on the secondary magnitude
of VS. For instance, if a close is acceptable while the system voltage ranges
from 90 percent to 105 percent of nominal, if the synchronism-check PT is
connected phase-to-neutral and the nominal line-to-neutral voltage is 67 V
secondary, then
25VLOX := 0.9 • 67 V secondary = 60.3 V secondary
25VHIX := 1.05 • 67 V secondary = 70.4 V secondary
When a phase-to-phase connected synchronism-check VT is used, the
nominal phase-to-phase voltage would probably be approximately 120 V
secondary, leading to
25VLOX := 0.9 • 120 V secondary = 108 V secondary
25VHIX := 1.05 • 120 V secondary = 126 V secondary
The 25VDIFX setting defines a maximum acceptable percentage difference
between the generator and system voltages. GENV+ defines whether the
generator voltage must be greater than the system voltage. Setting
25VDIFX := OFF disables this supervision and permits a close when both
voltages are within the voltage window described earlier.
For instance, the generator and prime mover manufacturer may recommend
that the generator voltage be between 0 percent and +3 percent of the system
voltage when the generator breaker is closed. In that case, set 25VDIFX := 3%
and GENV+ := Y. If a close is permitted when the generator voltage is within
±5 percent of the system voltage, set 25VDIFX := 5% and GENV+ := N.
Содержание SEL-700G Series
Страница 14: ...This page intentionally left blank ...
Страница 22: ...This page intentionally left blank ...
Страница 32: ...This page intentionally left blank ...
Страница 52: ...This page intentionally left blank ...
Страница 106: ...This page intentionally left blank ...
Страница 510: ...This page intentionally left blank ...
Страница 560: ...This page intentionally left blank ...
Страница 578: ...This page intentionally left blank ...
Страница 588: ...This page intentionally left blank ...
Страница 604: ...This page intentionally left blank ...
Страница 634: ...This page intentionally left blank ...
Страница 738: ...This page intentionally left blank ...
Страница 802: ...This page intentionally left blank ...
Страница 816: ...This page intentionally left blank ...