Pick-up characteristics
Pick-up of the HOC function is controlled by Ihset pu, Ih/IL (depends of the selected operating mode)
setting parameter, which de nes the maximum allowed measured current before action from the
function. The function constantly calculates the ratio in between of the Ihset pu or Ih/IL and measured
magnitude (Im) per all three phases. Reset ratio of 97 % is inbuilt in the function and is always related
to the Ihset / Ih/IL value. 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. 5.4.6. - 83. Pick-up characteristics setting
Name
Range
Step
Default
Description
Ihset pu
0.05 … 2.00 x In
0.01 x In
0.20 x In
Pick-up setting
(per unit monitoring)
Ih/IL
5.00…200.00 %
0.01 %
20.00 %
Pick-up setting
(percentage monitoring)
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 trip and reset
This function supports de nite time delay (DT) and inverse de nite minimum time (IDMT) delay types.
For detailed information on these delay types refer to chapter General properties of a protection
function.
Events and registers
The HOC 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 HOC 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.
AQ-T257
Instruction manual
Version: 2.00
© Arcteq Relays Ltd
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