ABB RELION REX640, Техническое руководство, Страница: 834 / 1960

OPERATE
Level
detector
BLOCK
START
I
2
/I
1
I3P
Min
current
check
t
Timer
I
2
I
1
I_A
I_B
I_C
Blocking
logic
Figure 471: Functional module diagram
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 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
Blocking mode.
The
Blocking mode setting has three blocking methods. In the "Freeze timers"
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
Protection functions 1MRS759142 F
834 REX640
Technical Manual