
4.41
Date Code 20170814
Instruction Manual
SEL-700G Relay
Protection and Logic Functions
Group Settings (SET Command)
Loss-of-Potential and Other Supervision
When 64G2 is configured as a third-harmonic voltage differential element, the
relay must have information about the level of third-harmonic voltage at the
generator terminal. If the potential transformers are lost, the 64G2 element
operates and causes an unnecessary trip unless the SEL-700G Relay loss-of-
potential detection logic (by setting 64G2TC := NOT LOPX AND 52AX, for
example) supervises the element.
Note that LOPX is associated with the terminal PTs wired on the X-side.
When external 3V0 is connected to the VS input (DELTAY_X := DELTA
and EXT3V0_X := VS), LOPX should not be used for supervising 64G2.
In hydro-generator applications, where overspeed after load rejection events is
possible, consider using an overfrequency element to disable the third-
harmonic elements. The change in generator frequency during overspeed can
cause unexpected operation of the third-harmonic elements. Other
supervision, such as for breaker position (52AX) or voltage (27PPX1), may be
necessary in some applications, for example, by setting 64G2TC := NOT
LOPX AND NOT 27PPX1.
100% Stator Ground Protection Setting Calculation
Collect the following information before setting the 100% Stator Ground
Protection.
➤
Generator nominal voltage, VNOM_X
➤
Generator grounding transformer ratio to 1 (use 1 if machine is
resistance grounded)
➤
Generator neutral voltage transformer ratio to 1 (use 1 if relay is
connected directly to grounding transformer secondary winding)
➤
Generator neutral voltage during system ground fault
(Capacitive coupling in the generator step-up transformer causes
this voltage). If this voltage is unknown, you can perform this
coordination on a time basis.)
➤
Relay settings PTRX, DELTAY_X, EXT3V0_X, and PTRN
Third-Harmonic Voltage Differential Setting Recommendations (Use
With Four-Wire Potentials or With Open-Delta Potentials and
External 3V0).
This setting procedure assists you in calculating 64G
element settings that offer secure, sensitive detection of stator winding faults.
As described, the 64G2 element characteristic has a midwinding dead band
whose width is governed by the 64G2P setting. The 64G1 neutral overvoltage
element provides sensitive detection of stator faults in the dead band when you
select its settings according to the following procedure.
ZONE 1 TIMER
0.00–400.00 s
64G1D := 0.75
64G1 TRQCTRL
SEL
OGIC
64G1TC := 1
DIFF VOLT LVL
OFF, 0.1–20.0 V
64G2P := 2.5
ZONE 2 RATIO
0.0–5.0
64RAT := 1.0
ZONE 2 TIMER
0.00–400.00 s
64G2D := 0.08
64G2 TRQCTRL
SEL
OGIC
64G2TC := 1
Table 4.6
Stator Ground Protection Settings
(Sheet 2 of 2)
Setting Prompt
Setting Range
Setting Name :=
Factory Default
Содержание SEL-700G Series
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