ABB RELION REX640 Technical Manual page 933

1MRS759142 F
Frequency
Start of operation timer
OPR_FRG
OPERATE
Figure 518: Load-shedding operation in the "Freq< AND df/dt>" mode when only the
df/dt condition is satisfied ( Rated frequency=50 Hz)
Restore detection
If after the activation of the OPERATE output the frequency recovers to a level above
the
output remains active for 100 ms. The
restoring mode to be "Disabled", "Auto" or "Manual".
Restoring mode
Disabled
Auto
Manual
REX640
Technical Manual
[Hz]
50 Hz
49 Hz
ST_FRG
500ms
Restore start Val setting, the RESTORE signal output is activated. The RESTORE
Description
Load restoration is disabled.
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
reached the value of the
output is activated if the restoring condition still persists. If the fre-
quency drops below the
is activated, the reset timer is activated. If the reset timer reaches
the value of the
ST_REST
In the "Manual" mode, a manual restoration is possible through the
MAN_RESTORE
activated if the
Start value Freq set at 0.975 xFn
Start value df/dt set at -0.020 xFn/s
Operate Tm df/dt = 500ms
Operate Tm Freq = 1000ms
Load shed mode = Freq< AND df/dt
1s
OPERATE is not
activated in this case
as Freq< condition not
satisfied
Restore mode setting is used to select the
ST_REST
Restore delay time setting, the
Restore start Val before the
Reset delay time setting, the timer resets and the
start output is deactivated.
input or via communication. The
command is available and the frequen-
MAN_RESTORE
Protection functions
Time [s]
output. When the timer has
RESTORE
output
RESTORE
output is
ST_REST
933