Read-only parameters
The relay's
Info page displays useful, real-time information on the state of the protection function. It is
accessed either through the relay's HMI display, or through the setting tool software when it is
connected to the relay and its Live Edit mode is active.
Table. 5.4.15 - 147. Information displayed by the function.
Name
Range
Step
Description
df/dt >/< LN
behaviour
1: On
2: Blocked
3: Test
4: Test/Blocked
5: Off
-
Displays the mode of DFT block.
This parameter is visible only when
Allow setting of individual LN
mode is enabled in General menu.
Measured df/dt
0.000...20.000Hz/s
0.001Hz/
s
Rate-of-change-of-frequency at the moment.
df/dt >/<
(1...8) condition
0: Normal
1: Start
2: Trip
3: Blocked
-
Displays the status of the protection function.
df/dt >/< (1...8)
df/dt meas / df/dt
set
0.000...20.000p.u.
0.005p.u. The ratio between the rate-of-change-of-frequency and the pick-up
value.
Expected
operating time
0.000...1800.000s
0.005s
Displays the expected operating time when a fault occurs.
Time remaining
to trip
-1800.000...1800.000s 0.005s
When the function has detected a fault and counts down time
towards a trip, this displays how much time is left before tripping
occurs.
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 startup frequency 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 rate-of-change of frequency function (abbreviated "DFT" 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 events triggered by the function are recorded with a time stamp and with process data values.
A
AQ
Q-M257
-M257
Instruction manual
Version: 2.07
172
© Arcteq Relays Ltd
IM00021
Summary of Contents for AQ-M257
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