Level detect
The operating signal is compared to the set
Start value
. If the operating signal
exceeds the set
Start value
, Level detector sends an enabling signal to the Timer
module.
Timer
Once activated, 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 operating signal persists. If a
drop-off situation happens, that is, the fault disappears before the operate delay is
exceeded, the timer reset state is activated. If the reset timer reaches the value set
by
Reset delay time
, the operation timer resets and the START output is deactivated.
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
function is blocked and the timers are reset. In the “Block OPERATE output” mode,
the function operates normally but the OPERATE output is not activated.
4.12.5.6 Operating quantity
Operating quantity in ungrounded SCB
Consider a case of a standard ungrounded shunt capacitor bank as shown in
Figure
644
.
1MRS759142 F
Protection functions
REX640
Technical Manual
1151
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