Restoring mode Description
Disabled Load restoration is disabled.
Auto In the “Auto” mode, input frequency is continuously compared to the
Restore
start Val
setting. The restore detection module includes a timer with the DT
characteristics. Upon detection of restoring, the operation timer activates the
ST_REST output. When the timer has reached the value of the
Restore delay
time
setting, the RESTORE output is activated if the restoring condition still
persists. If the frequency drops below the
Restore start Val
before the
RESTORE output is activated, the reset timer is activated. If the reset timer
reaches the value of the
Reset delay time
setting, the timer resets and the
ST_REST start output is deactivated.
Manual In the “Manual” mode, a manual restoration is possible through the
MAN_RESTORE input or via communication. The ST_REST output is activated
if the MAN_RESTORE command is available and the frequency has exceeded
the
Restore start Val
setting. The manual restoration includes a timer with
the DT characteristics. When the timer has reached the set value of the
Restore delay time
setting, the RESTORE output is activated if the restoring
condition still persists. If the frequency drops below the
Restore start Val
setting before the RESTORE output is activated, the reset timer is activated. If
the reset timer reaches the value of the
Reset delay time
setting, the timer
resets and the ST_REST start output is deactivated.
A condition can arise where the restoring operation needs to be canceled.
Activating the BLK_REST input for the "Auto" or "Manual" modes cancels the
restoring operation. In the "Manual" restoring mode, the cancellation happens even
if MAN_RESTORE is present.
Once the RESTORE output command is cancelled, the reactivation of RESTORE is
possible only after the reactivation of the OPERATE output, that is, when the next
load-shedding operation is detected.
Blocking logic
There are three operation modes in the blocking functionality. The operation modes
are controlled by the BLOCK input and the Configuration/System/Blocking mode
global setting that selects the blocking mode. The BLOCK input can be controlled
with a binary input, a horizontal communication input or an internal signal of the
IED program. The influence of the BLOCK input signal activation is preselected
with the Blocking mode global setting.
The Blocking mode setting has three blocking methods. In the "Freeze timers"
mode, the operate timer is frozen to the prevailing value. 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, OPR_FRQ and
OPR_FRG outputs are not activated.
4.6.2.5 Application
An AC power system operates at a defined rated frequency. The nominal frequency
in most systems in the world is 50 Hz or 60 Hz. The system operation is such that
the operating frequency remains approximately at the nominal frequency value by
Section 4 1YHT530004D05 D
Protection functions
508 615 series
Technical Manual
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