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Functions
152
7UM62 Manual
C53000-G1176-C149-3
Setting Values
Address
serves to specify the measured quantities used by the
protection feature. The default setting (normal case) is specified for phase-to-phase
voltages (=
). The phase-earth-voltages should be selected for low-voltage
machines with grounded neutral conductor (=
). It should be noted that even
if phase-earth voltages are selected as measured quantities, the setting values of the
protection functions are referred to phase-to-phase voltages.
The setting of limit values and time delays of the overvoltage protection depends on
the speed with which the voltage regulator can regulate voltage variations. The
protection must not intervene into the regulation process of the fault-free functioning
voltage regulator. For this reason, the two-stage characteristic must always be above
the voltage time characteristic of the regulation procedure.
The long-time stage
U> and
must intervene in case of steady-state
overvoltages. It is set to approximately 110 % to 115 % U
N
and, depending on the
regulator speed, to a range between 1.5 s and 5 s.
In case of a full-load rejection of the generator, the voltage increases first in relation to
the transient voltage. Only by this time, the voltage regulator reduces it again to its
nominal value. The U>>-stage is set as short-time stage in a way that the transient
procedure in case of a full-load rejection does not lead to a tripping. For example, for
about 130 % U
N
with a
delay of zero to 0.5 s are typical
values.
All setting times are additional time delays which do not include the operating times
(measuring time, drop-out time) of the protective function.
The drop-out ratio at the address
can be adapted in small
steps to the operating conditions and used for highly precise signalizations (e.g.
network infeed of wind power stations).
2.20.2.1 Settings of the Overvoltage Protection
2.20.2.2 Information for the Overvoltage Protection
Addr.
Setting Title
Setting Options
Default Setting
Comments
4101
OVERVOLTAGE
OFF
ON
Block relay for trip com-
mands
OFF
Overvoltage Protection
4102
U>
30.0..170.0 V
115.0 V
U> Pickup
4103
T U>
0.00..60.00 sec;
∞
3.00 sec
T U> Time Delay
4104
U>>
30.0..170.0 V
130.0 V
U>> Pickup
4105
T U>>
0.00..60.00 sec;
∞
0.50 sec
T U>> Time Delay
4106A
U> DOUT RATIO
0.90..0.99
0.95
U> Drop Out Ratio
4107A
VALUES U>
Voltage protection with U-
Phase-Phase
Voltage protection with U-
Phase-earth
Voltage protection
with U-Phase-
Phase
Measurement Values for U>
F.No.
Alarm
Comments
06513 >BLOCK O/V
>BLOCK overvoltage protection