Functions
40
7UM62 Manual
C53000-G1176-C149-3
Undervoltage
Seal–In
The
U< undervoltage stage (positive-sequence voltage) is set to a value below
the lowest phase-to-phase voltage permissible during operation, e.g. 80 V.
The seal-in time
limits the pickup seal-in introduced by the
overcurrent/undervoltage. It must be set to a value higher than the
time delay.
The dropout ratio r = I
PU
/I
DO
of the overcurrent pickup I> is specified at the address
. The recommended value is r = 0.95. For special
applications, e.g. overload warning, it can be set to a higher value (0.98).
Example:
Pickup value
1.4
⋅
I
N Gen.
Tripping time delay
3 s
Undervoltage seal-in
0.8
⋅
U
N Gen.
Seal-in time of U<
4 s
Drop-out ratio
0.95
Nominal current I
N, Gen
483 A
Nominal voltage U
N, Gen
6.3 kV
Nominal current I
N, CT, prim
500 A
Nominal voltage U
N, VT, prim
6.3 kV
Nominal current I
N, sec
1 A
Nominal voltage U
N, sec
100 V
The following secondary setting values result from this specification:
2.6.2.1
Settings for the Definite-Time Overcurrent Protection (Stage I>)
The following list indicates the setting ranges and the default settings of a I
N
= 1 A
secondary nominal current. For a secondary nominal current of I
N
= 5 A, these values
must be multiplied by 5.
1.4 I
⋅
N, Gen
I
N, CT, prim
-----------------------------
=
I
N, sec
⋅
1.4 483 A
⋅
500 A
----------------------------
1 A
⋅
1.35 A
=
=
0.8 U
⋅
N, Gen
U
N, VT, prim
--------------------------------
=
c
⋅
0.8 6,3 kV
⋅
6.3 kV
-----------------------------
100 V
⋅
80 V
=
=
I>
U<
Addr.
Setting Title
Setting Options
Default Setting
Comments
1201
O/C I>
OFF
ON
Block relay for trip com-
mands
OFF
Overcurrent Time Protection I>
1202
I>
0.05..20.00 A
1.35 A
I> Pickup
1203
T I>
0.00..60.00 sec;
∞
3.00 sec
T I> Time Delay
1204
U< SEAL-IN
ON
OFF
OFF
State of Undervoltage Seal-in
1205
U<
10.0..125.0 V
80.0 V
Undervoltage Seal-in Pickup
1206
T-SEAL-IN
0.10..60.00 sec
4.00 sec
Duration of Undervoltage Seal-in
1207A
I> DOUT RATIO
0.90..0.99
0.95
I> Drop Out Ratio
