Function blocking
The block signal is checked in the beginning of each program cycle. The blocking signal is received
from the blocking matrix in the function's 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 the blocking signal is active when the pick-up element activates, a BLOCKED signal is generated and
the function does not process the situation further. If the START function has been activated before the
blocking signal, it resets and the release time characteristics are processed similarly to when the pick-
up signal is reset.
The blocking of the function causes an HMI display event and a-time stamped blocking event with
information of the impedance values.
The blocking signal can also be tested in the commissioning phase by a software switch signal when
the relay's testing mode "Enable stage forcing" is activated (
General
→
Device).
The variables the user can set are binary signals from the system. The blocking signal needs to reach
the device minimum of 5 ms before the set operating delay has passed in order for the blocking to
activate in time.
Events and registers
The underimpedance protection function (abbreviated "UIM" in event block names) generates events
and registers from the status changes in START, TRIP and BLOCKED. The user can select which event
messages are stored in the main event buffer: ON, OFF, or both. The function offers two (2)
independent stages; the events are segregated for each stage operation.
The events triggered by the function are recorded with a time stamp and with process data values.
Table. 5.4.24 - 207. Event messages.
Event block name
Event names
UIM1
Start ON
UIM1
Start OFF
UIM1
Trip ON
UIM1
Trip OFF
UIM1
Block ON
UIM1
Block OFF
UIM2
Start ON
UIM2
Start OFF
UIM2
Trip ON
UIM2
Trip OFF
UIM2
Block ON
UIM2
Block OFF
The function registers its operation into the last twelve (12) time-stamped registers. The register of the
function records the ON event process data for START, TRIP or BLOCKED. The table below
presents the structure of the function's register content.
A
AQ
Q-M257
-M257
Instruction manual
Version: 2.07
260
© Arcteq Relays Ltd
IM00021
Summary of Contents for AQ-M257
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