ABB SPAU 140 C User Manual And Technical Description page 24

Synchro-check
function
Settings for the
synchro-check
function
4
The synchro-check function is used for check-
ing whether CB closing is permitted or not.
Before CB operation the following closing con-
ditions must be fulfilled:
- The network sections on both sides of the CB
must be energized. The voltage magnitudes
of the energized networks are determined by
the set value for the upper threshold voltage
U .
max
- The voltage difference over the CB must be
small enough. The voltage difference allowed
is determined by the set voltage difference
value ∆U.
- The frequencies of the network sections (vol-
tages) to be connected shall not differ too
much from each other. The frequency conditi-
ons are fulfilled when the allowed frequency
difference of the networks to be connected is
smaller than the set frequency difference value
∆f.
≥ U ≥ U
U , U
1 max 3
≤ ∆U
U - U
1 3
≤ ∆f
f - f
1 3
∆ϕ ≤ ∆ϕ
13
Fig. 2. Closing conditions to be checked according to the synchronism check scheme. The closing
conditions for operation stage 2 are checked correspondingly between the voltages U2 and U3.
The threshold voltage U
measured bus/line network voltage must be be-
fore the network is considered to be energized.
The set threshold voltage value is the same for
the synchro-check function of both stages.
- Voltage difference allowed, absolute value ∆U.
The set value determines the maximum al-
lowed voltage difference for the synchro-check
function of both stages.
- Frequency difference allowed, absolute value
∆f. The set value determines the maximum
allowed frequency difference for the synchro-
check function of both stages.
- The phase-angle difference allowed, ∆ϕ, is an
absolute value which means that there are no
demands concerning the phase-angle direc-
tion. The set value determines the maximum
allowed phase-angle difference for the synchro-
check function of both stages.
max
, above which the
max
- The network sections to be connected (vol-
tages) have the same phase angle. The phase
angle conditions are fulfilled when the allowed
phase angle difference between the network
voltages is smaller than the set phase angle
difference ∆ϕ.
- The validity time t
valid
tions, achieved from frequency and phase-an-
gle differencies must have a duration of at least
the time needed for closing of the circuit
breaker to be operated (operate time of CB).
When the closing conditions mentioned above
are fulfilled simultaneously, the network voltages
are considered to be synchronized and a closing
command signal to the CB is delivered.
U
1
SC
25
- Operate time of circuit breakers, t
t . The operate time of the circuit breaker
CB23
controlled by a specific stage is separately set
for the stage concerned. In applications, where
the closing signal of the stage is not used di-
rectly for circuit breaker closing, but as a com-
mand signal to the control module CM, the
total operate time for closing is set by calcu-
lating the operate time of the control module
and the circuit breaker.
The operate time of the circuit breaker in the
synchro-check function is used to assure that
the closing conditions, especially at great fre-
quency difference values, are fulfilled at the mo-
ment when the circuit breaker is to be closed.
- The synchro-check functions of the different
stages are optional, i.e. these functions may
be activated or set out of operation by means
of function selector switches. The synchro-
check function of stage 1 and stage 2 is acti-
vated or deactivated by means of switches
SGF/3 and SGF/7, respectively; See chapter
"Function selector switches".
for CB closing condi-
U
3
and
CB13