ABB RELION REX640 Technical Manual page 834

Protection functions
Figure 471: Functional module diagram
I /I
2 1
The I
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 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
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
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
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 function. The operation modes
are controlled by the BLOCK input and the global setting in 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 of the protection relay's program. The influence of the BLOCK signal activation
is preselected with the global setting
The
mode, the operation timer is frozen to the prevailing value, but the OPERATE output
is not deactivated when blocking is activated. In the "Block all" mode, the whole
834
I
2
I
1
I3P
I_A
I_B
I_C
BLOCK
/I module calculates the ratio of the negative and positive sequence current.
2 1
Min phase current . At least one of the phase currents needs to be
Reset delay time , the operate timer resets and the START output is
Blocking mode setting has three blocking methods. In the "Freeze timers"
Level
I /I
2 1
detector
Min
current
check
Start value . If the calculated value exceeds the set
Blocking mode .
1MRS759142 F
Timer
OPERATE
t
START
Blocking
logic
Operate
Technical Manual
REX640