Table 1045:
Operation mode types
Operation Mode
Description
"Under"
If the input signal
AI_VALUE
is lower than
the set value of the "Start value" setting, the
level detector enables the timer module.
"Over"
If the input signal
AI_VALUE
exceeds the set
value of the
Start value
setting, the level de-
tector enables the timer module.
The
Absolute hysteresis setting can be used for preventing unnecessary oscillations
if the input signal is slightly above or below the
Start value setting. After leaving the
hysteresis area, the start condition has to be fulfilled again and it is not sufficient
for the signal to only return to the hysteresis area. If the
ENA_ADD
input is activated,
the threshold value of the internal comparator is the sum of the
Start value Add
and
Start value settings. The resulting threshold value for the comparator can be
increased or decreased depending on the sign and value of the
Start value Add
setting.
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 starting condition disappears
before the module operates, the reset timer is activated. If the reset timer reaches
the value set by
Reset delay time, the operation 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.
4.11.5
Application
The function block can be used for any general analog signal protection, either
underprotection or overprotection. The setting range is wide, allowing various
protection schemes for the function. Thus, the absolute hysteresis can be set to
a value that suits the application.
1MRS759142 F
Protection functions
REX640
Technical Manual
1107