A070687 V2 EN
Figure 241: Functional module diagram. I
1
and I
2
represent positive and
negative phase sequence currents. I_A, I_B and I_C represent
phase currents.
I
2
/I
1
The I
2
/I
1
module calculates the ratio of the negative and positive sequence current.
It reports the calculated value to the level detector.
Level detector
The level detector compares the calculated ratio of the negative- and positive-
sequence currents to the set Start value. If the calculated value exceeds the set Start
value and the min current check module has exceeded the value of Min phase
current, the level detector reports the exceeding of the value to the timer.
Min current check
The min current check module checks whether the measured phase currents are
above the set Min phase current. At least one of the phase currents needs to be
above the set limit to enable the level detector module.
Timer
Once activated, the timer activates the START output. The time characteristic is
according to DT. When the operation timer has reached the value set by Operate
delay time, the OPERATE output is activated. If the fault disappears before the
module operates, the reset timer is activated. If the reset timer reaches the value set
by Reset delay time, the operate timer resets and the START output is deactivated.
The timer calculates the start duration value START_DUR, which indicates the
percentage ratio of the start situation and the set operation time. The value is
available in the monitored data view.
Blocking logic
There are three operation modes in the blocking functionality. The operation modes
are controlled by the BLOCK input and the global setting "Configuration/System/
Blocking mode" which selects the blocking mode. The BLOCK input can be
controlled by a binary input, a horizontal communication input or an internal signal
1YHT530004D05 D Section 4
Protection functions
615 series 453
Technical Manual
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