5
Voltage-check
function
The voltage-check function is required when a
disconnected bus/line is to be connected to an
energized section of a network. By means of the
threshold voltages U
max
and U
min
of the syn-
chro-check module, the threshold values for an
energized or non-energized bus/line are set. Fur-
thermore, the energizing direction is supervised
by the voltage-check function. The energizing
direction of the module can be selected by means
of function selector switches and the settings
determine which side of the circuit breaker to
be closed shall be energized or non-energized.
For the voltage-check function the energizing
direction of each stage can be selected from four
different alternatives. The available energizing
directions are as follows:
a) U
1
≥
U
max
, U
3
≤
U
min
or
U
1
≤
U
min
, U
3
≥
U
max
b) U
1
≥
U
max
, U
3
≤
U
min
c) U
1
≤
U
min
, U
3
≥
U
max
d) U
1
≤
U
min
, U
3
≤
U
min
or
U
1
≥
U
max
, U
3
≤
U
min
or
U
1
≤
U
min
, U
3
≥
U
max
VC
U
1
U
3
Fig. 3. Influence of voltage-check conditions on the delivering of a closing signal.
When the voltage-check conditions are fulfilled,
they have to persist continuously for a pre-set
operate time (dead time), before the releasing
of a final closing signal is permitted. Thus, it is
assured that the non-energized time of the net-
work is long enough for releasing a closing sig-
nal and that it, is not caused by short-time volt-
age failures in the network sections. When the
voltage-check conditions have been fulfilled long
enough a closing signal is delivered to the cir-
cuit breaker.
Settings for the
voltage-check
function
- The threshold voltage U
max
, above which the
measured bus/line network voltage must be
before the network is considered to be ener-
gized. The set threshold voltage value is the
same for the voltage-check function of both
stages. The set threshold value applies to the
synchro-check function as well.
- The threshold value U
min
, below which the
measured bus/line network voltage must be
before the network is considered to be non-
energized. The set threshold voltage value is
the same for the voltage-check function of
both stages.
Note!
Because the setting ranges of the threshold vol-
tages U
max
and U
min
partly overlap each other,
the setting conditions may be such, that the set-
ting of the non-energized threshold value U
min
is higher than the setting of the energized thres-
hold value U
max
. The setting parameters should
be done carefully by the user to avoid the set-
ting conditions mentioned above.
- Operate time t
VC
for the energizing opera-
tion (dead time). The set operate time applies
to the voltage-check function of both stages.
- The energizing direction is separately selected
by means of function selector switches for both
voltage-check stages. The energizing direction
of stage 1 is selected by means of switches SGF/1
and SGF/2 and the direction of stage 2 is se-
lected with switches SGF/5 and SGF/6; See
chapter "Function selector switches". For ex-
ample, when the energizing direction of stage
1 is selected to be U1
→
U3 (SGF/1=1, SGF/
2=0), the voltage U1 shall be higher than U
max
and the voltage U3 lower than U
min
before
the conditions of the energizing direction are
fulfilled.
- The voltage-check functions of the separate
stages are optional, i.e. these functions may
be activated or set out of operation by means
of function selector switches. The voltage
check function of stage 1 and stage 2 is acti-
vated or deactivated by means of switches
SGF/4 and SGF/8, respectively; See chapter
"Function selector switches".
