Siemens SIPROTEC 7UT613 series Manual page 248

2 Functions
Pickup Seal-in Time
Delay Time
248
active power referenced to the rated apparent power of the protected
object
S Nominal apparent power of protected object
N Obj
Example:
Generator
Current transformer
Voltage transformer
perm. reverse power
In case of setting related to address 5012
Pr pick-up = - 0,03
In case of setting in Watt secondary address 5011
Pr pick-up =
Intermitting pickups are delayed to the set minimum time by means of the pickup seal-
in time under address 5015 T-HOLD. Usually, these are not required and set to
0.00 sec. This parameter can only be set with DIGSI at Additional Settings. If a trip
is desired in case of intermitting reverse power, the maximum time interval that may
pass between two pickup impulses must be set here, if it is supposed to be interpreted
as a continuous pickup.
The following applies to generator applications: If reverse power without emergency
tripping is used, a corresponding time delay must be implemented to bridge any short
reverse power states after synchronisation or power swings subsequent to system
faults (e.g. 3-pole short circuit). Usually, a delay time 5013 T-SV-OPEN of approx.
10.00 sec is set.
In case of faults causing an emergency tripping, the reverse power protection per-
forms a short-time delayed switchoff subsequent to the emergency tripping via an oil-
pressure switch or a position switch at the emergency trip valve. Before tripping, it
must be ensured that the reverse power is only caused by the missing drive power at
the turbine side. A time delay is necessary to bridge the active power swing in case of
sudden valve closing, until a steady state active power value is achieved. A time delay
5014 T-SV-CLOSED of about 1 to 3 s is sufficient for this purpose, whereas a time
delay of about 0.5 s is recommended for gas turbine sets. The set times are additional
delay times not including the operating times (measuring time, dropout time) of the
protective function. Please note that averaging over 16 periods is executed during
"precise" measuring procedures; the operating time is thus respectively higher. This
is recommended when used as reverse power protection for generators, this is recom-
mended (default setting address 5016 Type of meas. = accurate).
In system applications the delay time depends on the type of application and should
overlap with the awaited grading times. The time is important T-SV-OPEN (address
5013). The time T-SV-CLOSED (address 5014) is usually not required in these cases
and set to ∞. As high precision of the active power measurement is usually not re-
quired here, address 5016 Type of meas. = fast can be set, thus enabling also
5.27 MVA
6.3 kV
500 A/5 A
6300 V/100 V
3 % = 0.03
7UT613/63x Manual
C53000-G1176-C160-2