Pick-up characteristics
Pick-up and activation of the THD function alarm is controlled by
IsetPh, IsetI01
and
IsetI02 pick-up
setting parameters, which de nes the maximum allowed measured current THD before action from the
function. In order to have alarm signals activated from the function, the corresponding pick-up element
needs to be activated by the
Enable PH, Enable I01
and
Enable I02
setting parameters. Each pick-up
element can be activated individually. The function constantly calculates the ratio in between of the
setting values and measured magnitude (Im) per all three phases. Reset ratio of 97 % is inbuilt in the
function and is always related to the settingvalue. The setting value is common for all measured phases
and single-, dual- or all phases Im exceed of the Iset value will cause pick-up operation of the function.
Table. 5.6.6. - 225. Pick-up characteristics setting
Name
Range
Step
Default
Description
Enable
PH
On
Off
-
Off
Enable of the THD alarm function from phase currents.
Enable
I01
On
Off
-
Off
Enable of the THD alarm function from residual current input I01.
Enable
I02
On
Off
-
Off
Enable of the THD alarm function from residual current input I02.
IsetPh
0.10 …
200.00% 0.01% 20.00%
Pick-up setting for THD alarm element from the phase currents. The measured THD
value has to be over this setting on at least one of the measured phases to activate
the alarm signal.
IsetI01 0.10 …
200.00% 0.01% 20.00%
Pick-up setting for THD alarm element from the residual current I01. The measured
THD value has to be over this setting to activate the alarm signal.
IsetI02 0.10 …
200.00% 0.01% 20.00%
Pick-up setting for THD alarm element from the residual current I02. The measured
THD value has to be over this setting to activate the alarm signal.
The pick-up activation of the function is not directly equal to start-signal generation of the function.
Start signal is allowed if blocking condition is not active.
Function 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 current 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 passedfor blocking to be active in time.
Operating time characteristics for activation and reset
The operating timers’ behavior of the function can be set for activation and the cold load pick up
situation monitoring and release.
AQ-T257
Instruction manual
Version: 2.00
285
© Arcteq Relays Ltd
