Functions
192
7UM62 Manual
C53000-G1176-C149-3
Pickup Value for
3rd Harmonics
Depending on the selection of the connection type, only one of the two setting
parameters
or
is accessible. The setting values can only be determined
within the framework of a primary test. The following principle is generally valid:
−
The
undervoltage stage is relevant for a connection to a
transformer in the starpoint. The pickup value should be chosen as low as possible.
−
The
overvoltage stage is relevant for a connection via the
broken delta winding of an earthing transformer and for a not connected, but
internally calculated displacement voltage.
Working Area
Due to the strong dependency of the measurable 3rd harmonic from the correspond-
ing working point of the generator, the working area of the 100–%–stator earth fault
protection is only tripped above the active-power threshold set via
and on exceeding a minimum positive phase-sequence voltage
Recommended setting:
P
min
> 40 % P/S
N
U
1 min
> 80 % U
N
Delay Time
The tripping in case of an earth fault is delayed by the time set at address
. The set time is an additional time delay not including the operating
time of the protective function.
2.28.2.1 Settings of the 100–%–Stator Earth Fault Protection with 3rd Harmonics
Addr.
Setting Title
Setting Options
Default Setting
Comments
5201
SEF 3rd HARM.
OFF
ON
Block relay for trip com-
mands
OFF
Stator Earth Fault Protection
3rdHarm.
5202
U0 3.HARM<
0.2..40.0 V
1.0 V
U0 3rd Harmonic< Pickup
5203
U0 3.HARM>
0.2..40.0 V
2.0 V
U0 3rd Harmonic> Pickup
5204
T SEF 3. HARM.
0.00..60.00 sec;
∞
0.50 sec
T SEF 3rd Harmonic Time Delay
5205
P min >
10..100 %; 0
40 %
Release Threshold Pmin>
5206
U1 min >
50.0..125.0 V; 0
80.0 V
Release Threshold U1min>