General settings
The following general settings de ne the general behavior of the function. These settings are static i.e.
it is not possible change them with setting group switching.
Name
Description
Range Step Default
Measured
magnitude
De nes if the ratio between positive and negative sequence currents are
supervised or if only negative sequence is used in unbalance detection.
1:I2pu
2:I2/I1
-
1:I2pu
Pick-up characteristics
Pick-up of the CUB function is controlled by I2set or I2/I1set setting parameters, which de ne the
maximum allowed measured negative sequence current or negative/positive sequence current ratio
before action from the function. The function constantly calculates the ratio in between of the Iset and
measured magnitude (Im). Reset ratio of 97 % is inbuilt in the function and is always related to the
Ixset value. The reset ratio is common for both modes.
Table. 5.4.7. - 89. Pick-up characteristics setting
Name
Description
Range
Step
Default
I2set
Pick-up setting for I2 mode
0.01…40.00xIn
0.01xIn
0.2xIn
I2/I1set
Pick-up setting for I2/I1 mode
1…200%
0.01%
20%
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.
AQ-F255
Instruction manual
Version: 2.00
93
© Arcteq Relays Ltd