Application Guide - NP900 Series
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A996A
3.2.16.7
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, a START signal
is generated and the function proceeds to the time characteristics calculation.
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. If START function has
been activated before blocking signal it will reset and the release time characteristics are
processed as in case of when pick-up signal is reset.
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.
User settable variables are binary signals from the system. Blocking signal needs to reach
the IED minimum of 5 ms before the set operating delay has passed for blocking to be
active in time.
3.2.16.8
O
PERATING TIME CHARACTERISTICS FOR TRIP AND RESET
This function supports definite time delay (DT) and inverse definite minimum time (IDMT)
delay types. For detailed information on these delay types refer to chapter General
properties of a protection function.
3.2.16.9
E
VENTS AND REGISTERS
The VUB function generates events and registers from the status changes of start, trip
and blocked. To main event buffer is possible to select status “On” or “Off” messages. The
VUB function offers four independent instances which events are segregated for each
instance operation.
In the function is available 12 last registers where the triggering event of the function
(start, trip or blocked) is recorded with time stamp and process data values.
