Schweitzer Engineering Laboratories SEL-700G Series, Instruction Manual

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4.129
Date Code 20170814 Instruction Manual SEL-700G Relay
Protection and Logic Functions
Group Settings (SET Command)
If both of the internal enables:
are deasserted, then factor k2 is ignored as a logic enable for the DIRQGE
internal enable. This effectively puts less restrictions on the operation of the
negative-sequence voltage-polarized directional element.
If enable setting EDIR := AUTO, setting k2 is set automatically at:
k2 := 0.2
For setting k2 = 0.2, the negative-sequence current (I
2
) magnitude has to be
greater than 1/5 of the zero-sequence current (I
0
) magnitude in order for the
negative-sequence voltage-polarized directional elements to be enabled
(|I
2
| > 0.2 • |I
0
|). Again, this presumes that at least one of the internal enables
DIRVE or DIRIE is asserted.
50GFP/50GRP—Forward/Reverse Directional Residual-Ground
Current Pickup.
If setting ORDER does not contain V or I (no zero-
sequence voltage-polarized or channel
IN
current-polarized directional
elements are enabled), then settings 50GFP and 50GRP are not made or
displayed.
The 50GFP setting (3I
0
current value) is the pickup for the forward fault
detector 50GF of the zero-sequence voltage-polarized and channel
IN
current-
polarized directional elements (see Figure 4.75). Ideally, this setting is above
normal load unbalance and below the lowest expected zero-sequence current
magnitude for unbalanced forward faults.
The 50GRP setting (3I
0
current value) is the pickup for the reverse fault
detector 50GR of the zero-sequence voltage-polarized and channel
IN
current-
polarized directional elements (see Figure 4.75). Ideally, this setting is above
normal load unbalance and below the lowest expected zero-sequence current
magnitude for unbalanced reverse faults.
If enable setting EDIR := AUTO, the settings 50GFP and 50GRP are set
automatically at:
50GFP = 0.50 A secondary (5 A nominal phase current inputs,
IA
,
IB
,
IC
)
50GRP = 0.25 A secondary (5 A nominal phase current inputs,
IA
,
IB
,
IC
)
50GFP = 0.10 A secondary (1 A nominal phase current inputs,
IA
,
IB
,
IC
)
50GRP = 0.05 A secondary (1 A nominal phase current inputs, IA , IB , IC )
a0—Positive-Sequence Current Restraint Factor, I
0
/I
1
.
If setting
ORDER does not contain V or I (no zero-sequence voltage-polarized or
channel
IN
current-polarized directional elements are enabled), then setting a0
is not made or displayed.
Refer to Figure 4.75. The a0 factor increases the security of the zero-sequence
voltage-polarized and channel
IN
current-polarized directional elements. This
factor keeps the elements from operating for zero-sequence current (system
DIRVE internal enable for the zero-sequence voltage-polarized
directional element that controls the neutral-ground and
residual-ground overcurrent elements
DIRIE internal enable for the channel
IN
current-polarized
directional element that controls the neutral-ground and
residual-ground overcurrent elements