Siemens siprotec SJ62 User Manual page 49

2 Functions
Transformation
Ratio of Voltage
Transformers (VTs)
Trip and Close
Command Dura-
tion (CB)
Current Flow Moni-
toring (CB)
Circuit Breaker
Maintenance (CBM)
47
In address 206 Vph / Vdelta the adjustment factor between phase voltage and dis-
placement voltage is communicated to the device. This information is relevant for the
detection of ground faults (in grounded systems and non-grounded systems), opera-
tional measured value V
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:
(secondary voltage, address 206 Vph / Vdelta) has the relation
The factor V /V
ph N
to 3/ √3 = √3 = 1.73 which must be used if the V
formation ratios, i.e. the formation of the displacement voltage via an interconnected
transformer set, the factor must be corrected accordingly.
Please take into consideration that also the calculated secondary V
by the value set in address 206 Vph / Vdelta. Thus, even if the V
connected, address 206 Vph / Vdelta has an impact on the secondary operational
measured value V .
N
Address 210 TMin TRIP CMD is used to set the minimum time the tripping contacts
will remain closed. This setting applies to all protective functions that initiate tripping.
Address 211 TMax CLOSE CMD is used to set the maximum time the closing contacts
will remain closed. This setting applies to the integrated reclosing function This setting
must be long enough to allow the circuit breaker contacts to reliably engage. An ex-
cessive duration causes no problem since the closing command is interrupted in the
event another trip is initiated by a protective function.
Address 212 BkrClosed I MIN corresponds to the threshold value of the integrated
current flow monitoring system. This parameter is used by several protection functions
(e.g. voltage protection with current criterion, breaker failure protection, overload pro-
tection, restart inhibit for motors and CB maintenance). If the configured current value
exceeds the setting, the circuit-breaker is considered closed.
The threshold value setting applies to all three phases, and must take into consider-
ation all used protective functions.
With regard to breaker failure protection, the threshold value must be set at a level
below the minimum fault current for which breaker failure protection must operate. A
setting of 10% below the minimum fault current for which breaker failure protection
must operate is recommended. The pickup value should not be set too low, otherwise,
the danger exists that transients in the current transformer secondary circuit could lead
to extended drop out times if extremely high currents are switched off.
When using the device for motor protection, overload 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 cool-down behaviour. For this application, the
set value must be lower than the minimum no-load current of the motor.
Parameters 260 to 267 are assigned to CB maintenance. The parameters and the dif-
ferent procedures are explained in the setting notes of this function (see Section
2.23.3).
and measured-quantity monitoring.
N
N
voltage is connected. For other trans-
-voltage is divided
N
-voltage is not
N
SIPROTEC 4, 7SJ62/63/64 Handbuch
C53000-G1140-C147-A, Edition 07.2015