3.4 Primary Commissioning Tests with the Generator
379
7UM62 Manual
C53000-G1176-C149-3
Figure 3-34
Earth Fault with Busbar Connection
The generator circuit breaker must be closed for this test and the generator
galvanically connected with the load equipment. If the plant conditions do not allow
this, the hints given overleaf under the side title “Directional check without Loading
Resistor” must be observed.
Start up generator and slowly excite until the stator earth fault protection picks up:
alarm “U0> picked up” (not allocated when delivered from factory). At the same time
the alarm “3I0> picked up” should appear, if marshalled.
Read out U
E
and I
EE
under
OPERATIONAL MEASURED VALUES
. If the connections
are correct, this value corresponds with the machine terminal voltage in percent,
referred to rated machine voltage (if applicable, deviating rated primary voltage of
earthing transformer or neutral earthing transformer must be taken into account). This
value also corresponds to the setting value
in address
.
The measured value I
EE2
should be approximately equal to or slightly higher than the
setting value
under address
This is to ensure that the protection zone that
is determined by the setting value
is not reduced by a too slow pick-up.
For protection zone Z the following applies:
Example:
Machine voltage at pick-up
0.1 x U
sec N
Measured value
U
E
= 10 V
Setting value
= 10 V
Protected zone
Z
= 90 %
G
7UM62
U
E
I
EE2
U
N
3
--------
100
3
----------
V
Σ
100
3
----------
V
R
L
Z
U
sec N
U0>
–
U
sec N
----------------------------------
100 %
⋅
=
