Functions
2.1 General
SIPROTEC, 7SJ62/64, Manual
C53000-G1140-C207-2, Release date 01.2008
48
Transformation Ratio of Voltage Transformers (VTs)
Address
206
Vph / Vdelta
informs the device of the adjustment factor between the phase voltage and the
displacement voltage. This information is relevant for the processing of ground faults (in grounded systems and
ungrounded systems), for the operational measured value VN and measured-variable monitoring.
If the voltage transformer set provides open delta windings and if these windings are connected to the device,
this must be specified accordingly in address
213
(see above margin heading "Voltage Connection"). Since the
voltage transformer ratio is normally as follows:
the factor V
ph
/V
N
(secondary voltage, address
206
Vph / Vdelta
) must be set to 3/
√
3 =
√
3 = 1.73 which
must be used if the V
N
voltage is connected. For other transformation ratios, i.e. the formation of the displace-
ment voltage via an interconnected transformer set, the factor must be corrected accordingly.
Please take into consideration that also the calculated secondary V
0
-voltage is divided by the value set in
address
206
. Thus, even if the V
0
-voltage is not connected, address
206
has an impact on the secondary op-
erational measured value VN.
Trip and Close Command Duration (Breaker)
In address
210
the minimum trip command duration
TMin TRIP CMD
is set. This setting applies to all protec-
tion functions that can initiate tripping.
In address
211
the maximum close command duration
TMax CLOSE CMD
is set. It applies to the integrated
reclosing function. It must be set long enough to ensure that the circuit breaker has securely closed. An exces-
sive duration causes no problem since the closing command is interrupted in the event another trip is initiated
by a protection function.
Current Flow Monitoring (Breaker)
In address
212
BkrClosed I MIN
the pickup threshold of the integrated current flow monitoring function can
be set. This parameter is used by several protection functions (e.g. voltage protection with current criterion,
overload protection, load jam protection, restart inhibit for motors and circuit breaker maintenance). If the set
current value is exceeded, the circuit breaker is considered closed.
The threshold value setting applies to all three phases, and must take into consideration all used protection
functions.
The pickup threshold for the circuit-breaker failure protection is set separately (see 2.16.2).
When using the device as motor protection and using the overload protection, load jam protection and restart
inhibit, the protective relay can distinguish between a running motor and a stopped motor, as well as take into
account the different motor cooldown behavior. For this application, the set value must be lower than the
minimum no-load current of the motor.
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