Thytronic Pro-N NVA100X-D

238
NVA100X-D - Manual - 02 - 2016
FUNCTION CHARACTERISTICS
External fault stabilization by means of operating dual-slope percentage characteristic
The start of the fi rst threshold of the differential protection on L1 phase (ST I
d
-L1) occurs when all the
following conditions are met:
87 Enable = ON
I
dL1
≥ I
d
>
I
dL1
≥ K1/100) ∙ I
SL1
I
dL1
≥ K2/100) ∙ I
SL1
- Q
87H
-REST-L1
= OFF
87
SatDet-L1
= OFF
BLK1 87 = OFF
where:
87 enable parameter for both the differential protection thresholds,
I
d
> adjustment of the minimum threshold (or maximum sensitivity) of the differential protection,
K1 adjustment as a percentage of the slope of the fi rst segment of the operating characteristic of
differential protection,
K2 adjustment as a percentage of the slope of the second segment of the operating characteristic
of differential protection,
Q y-axis intercept of the line of the second segment of the operating characteristic of differential
protection,
87H
-REST-L1
logic state output of the the second and fi fth harmonic restraint for phase L1,
87
SatDet-L1
logic state output of the CT’s saturation detector for phase L1,
BLK1 87 logic state output of the logic block function of the differential protection.
All differential elements can be enabled or disabled by setting ON or OFF the 87T Enable param-
eter inside the Set \ Profi le A(or B) \ Differential 87G-87M-87T \ Common confi guration menu.
The I
d
>, K1, K2 and Q parameters are available inside the Input sequence \ Id> Element \ defi nite
time.
Similarly the start of the fi rst threshold of the differential protection on L2 (ST I
d
>-L2) or L3 (ST I
d
>-L3)
phase occurs when all the following conditions are met:
87 Enable = ON
I
dL2
≥ I
d
>
I
dL2
≥ K1/100) ∙ I
SL2
I
dL2
≥ K2/100) ∙ I
SL2
- Q
87H
-REST-L2
= OFF
87
SatDet-L2
= OFF
BLK1 87 = OFF
87 Enable = ON
I
dL3
≥ I
d
>
I
dL3
≥ K3/100) ∙ I
SL3
I
dL3
≥ K2/100) ∙ I
SL3
- Q
87H
-REST-L3
= OFF
87
SatDet-L3
= OFF
BLK1 87 = OFF
where 87H
-REST-L2
and 87H
-REST-L3
are the output state of the second or fi fth harmonic restraint
for L2 and L3 phases respectively, 87
SatDet-L2
and 87
SatDet-L3
are the output state of the saturation
detector for L2 and L3 phases.
The start of the fi rst differential protection element (ST I
d
>) occurs at the instant of occurrence of
the threshold start in at least one of the L1, L2, L3 phases.
If the three conditions that led to the start of the fi rst threshold of the differential protection on L1,
L2, L3 phases are maintained all for the duration of intentional delay t
d
>, when the time expires the
element trips.
The start of the second threshold of the differential protection on L1 phase (ST I
d
>>-L1) occurs when
all the following conditions are met:
87 Enable = ON
I
dL1
≥ I
d
>>
BLK1 87 = OFF
where I
d
>> is the setting threshold of the differential protection element.
Similarly the start of the second threshold of the differential protection on L2 (ST I
d
>>-L2) or L3
(ST I
d
>>-L3) phase occurs when all the following conditions are met:
87 Enable = ON
I
dL2
≥ I
d
>>
BLK1 87 = OFF
87 Enable = ON
I
dL3
≥ I
d
>>
BLK1 87 = OFF
The operation of the second differential protection threshold (TR I
d
>>) occurs at the instant when the
intervention occurs the threshold in at least one of the L1, L2, L3 phases.
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