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4.77
Date Code 20170814
Instruction Manual
SEL-700G Relay
Protection and Logic Functions
Group Settings (SET Command)
Out-of-Step Element
The SEL-700G contains an out-of-step element to detect out-of-step
conditions between two electrical sources. Two interconnected systems can
experience an out-of-step condition for several reasons. For example, loss of
excitation can cause a generator to lose synchronism with the rest of the
system. Similarly, delayed tripping of a generator breaker to isolate a fault can
cause the generator to go out of step with the rest of the system.
Detecting and isolating an out-of-step condition as early as possible is
imperative, because the resulting high peak currents, winding stresses, and
high shaft torques can be very damaging to the generator and the associated
generator step-up transformer.
The SEL-700G implements two out-of-step tripping schemes: single blinder
and double blinder. Users can select whichever scheme suits their application,
or they can disable out-of-step protection.
Set E78 := 1B or 2B to enable out-of-step protection elements. If out-of-step
protection is not necessary, set E78 := N.
Table 4.15
Out-of-Step Protection Settings
Setting Prompt
Setting Range
Setting Name :=
Factory Default
OUT-OF-STEP PROT
N, 1B, 2B
E78 := 1B
FORWARD REACH
0.1–100.0 ohms
a
a
Ranges and default settings shown are for 5 A CT. Multiply by 5 for 1 A rated CTs.
78FWD := 8
REVERSE REACH
0.1–100.0 ohms
78REV := 8
RIGHT BLINDER
b
b
Right/Left Blinder settings apply to single-blinder scheme (1B) only.
0.1–50.0 ohms
78R1 := 6
LEFT BLINDER
0.1–50.0 ohms
78R2 := 6
OUTER BLINDER
c
c
Outer/Inner Blinder and OOS Delay settings apply to double-blinder scheme (2B) only.
0.2–100.0 ohms
78R1 := 6
INNER BLINDER
0.1–50.0 ohms
78R2 := 6
OOS DELAY
0.00–1.00 s
78D := 0.05
OOS TRIP DELAY
0.00–1.00 s
78TD := 0
OOS TRIP DUR
0.00–5.00 s
78TDURD := 0
POS-SEQ CURRENT
0.25-30.00 A
d
d
Range and default setting shown are for 5 A CT. Divide by 5 for 1 A rated CTs.
50ABC := 0.25
OOS TRQCTRL
SEL
OGIC
OOSTC := 1
Содержание SEL-700G Series
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