Application Guide - NP900 Series
166 (504
)
A996A
3.2.15.3
U
SING
B
LOCK SETTING TO PREVENT NUISANCE TRIPS
To prevent the relay from tripping in a situation where the network is de-energized it is
advised to use the
Block setting
parameter. When the measured voltage drops below the
set value relay will not give an alarm or trip signal. If the measured voltage has dropped
below the
Block setting
the blocking will persist until all of the line voltages have risen over
the
U< pick-up setting
. Please see the image for a visualization of this function.
Figure 3.2.15.3-85 Block setting operation example. If Block setting is set to zero blocking
is not in use.
3.2.15.4
F
UNCTION BLOCKING
In the blocking element the block signal is checked in the beginning of each program
cycle. Blocking signal is received from the blocking matrix for the function dedicated input.
If the blocking signal is not activated when the pick-up element activates, an ALARM or
TRIP signal is generated.
If blocking signal is active when pick-up element activates a BLOCKED signal will be
generated and the function shall not process the situation further.
From blocking of the function a HMI display event as well as time stamped blocking event
with information of the startup voltage values and fault type is issued.
Blocking signal can be tested also in the commissioning phase of the stage by software
switch signal when relay common and global testing mode is activated.
Содержание NP900 Series
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Страница 49: ...Application Guide NP900 Series 49 504 A996A Figure 3 2 1 3 25 Definite time operating characteristics...
Страница 50: ...Application Guide NP900 Series 50 504 A996A Figure 3 2 1 3 26 IEC predefined characteristics NI VI LTI and EI...
Страница 52: ...Application Guide NP900 Series 52 504 A996A Figure 3 2 1 3 28 IEEE predefined characteristics EI MI and VI...
Страница 243: ...Application Guide NP900 Series 243 504 A996A Figure 3 3 2 1 122 NPS biased thermal trip curves with kNPS values 7 and 10...
Страница 491: ...Application Guide NP900 Series 491 504 A996A 3 7 5 6 SETTING EXAMPLE...
Страница 504: ...Application Guide NP900 Series 504 504 A996A A996A...