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 passedfor blocking to be active in time.
Events
The FLX function generates events and registers from the status changes of triggering and calculation
statuses. To main event buffer it’s possible to select status “On” or “Off” messages.
12 latest registers where the triggering event of the function (start, trip or blocked) is recorded with
time stamp and process data values are available in the function.
Table. 5.6.6. - 238. Event codes of FLX function.
Event Number
Event channel
Event block name
Event Code
Description
2752
43
FLX1
0
Flocator triggered On
2753
43
FLX1
1
Flocator triggered Off
2754
43
FLX1
2
Flocator Calculation On
2755
43
FLX1
3
Flocator Calculation Off
In the table below is presented the structure of FLX function register content. This information is
available in 12 last recorded events.
Table. 5.6.6. - 239. Register content.
Date & Time
Event
code
Fault
type
Fault direction
Fault
reactance
Fault
Current
Fault
Current
Fault
distance
Setting
group in
use
dd.mm.yyyy
hh:mm:ss.mss
2752-
2755 Descr.
L1-L2;
L2-L3;
L3-L1;
L1-N;
L2-N;
L3-N;
L1-L2-
L3
Not detected;
Forward; Reverse
In Ohms
In per
unit
value
In
primary
value
In km
SG 1-8
5.6.7. Total harmonic distortion monitor (THD)
Total harmonic distortion monitor function (THD) is used for monitoring the current harmonic content.
THD is a measurement of the harmonic distortion present and is de ned as the ratio of the sum of
powers of all harmonic components to the power of fundamental frequency.
Harmonics can be caused by different sources in the electric networks like electric machine drives,
thyristor controls etc. Monitoring of the THD of the currents can be used to alarm in case if the
harmonic content rises too high in cases if either the electric quality requirement exist in the protected
unit or in cases if process generated harmonics needs to be monitored.
THD function measures constantly phase and residual current magnitudes and the harmonic content of
the monitored signals up to 31.st harmonic component. When the THD function is activated the THD
measurements are available for displays also. User has possibility to set also the alarming limits for
each measured channels if required by the application.
THD of the measured signals can be selected either amplitude- or power ratio THD. The difference is in
the calculation formula:
AQ-F255
Instruction manual
Version: 2.00
293
© Arcteq Relays Ltd