4.5.3.5
Operation principle
The function can be enabled and disabled with the
Operation setting. The
corresponding parameter values are "On" and "Off".
The operation of ROVPTOV can be described by using a module diagram. All the
modules in the diagram are explained in the next sections.
OPERATE
Level
detector
URES
BLOCK
START
Blocking
logic
t
Timer
U
O
Figure 487: Functional module diagram
Level detector
The residual voltage is compared to the set
Start value. If the value exceeds the set
Start value, the level detector sends an enable signal to the timer.
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
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.
Protection functions
1MRS759142 F
868
REX640
Technical Manual