ABB RELION REX640 Technical Manual page 923

1MRS759142 F
Operation mode
df/dt
Freq< + df/dt
Freq> + df/dt
Table continues on the next page
REX640
Technical Manual
Description
If the frequency restores before the module operates, the
reset timer is activated. If the timer reaches the value set
Reset delay Tm Freq setting, the operate timer resets
by the
and the and
START STR_OFRQ
The function operates independently as the frequency gra-
dient ("df/dt"), rate-of-change, protection function. When
the frequency gradient exceeds the set value of the
value df/dt setting, the module activates the
outputs. The time characteristic is according to
STR_FRG
DT. When the operation timer has reached the value set by
the Operate Tm df/dt setting, the
outputs are activated. If the frequency gradient restores be-
fore the module operates, the reset timer is activated. If the
timer reaches the value set by the
ting, the operate timer resets and the
outputs are deactivated.
A consecutive operation is enabled between the protection
methods. When the measured frequency is below the set
value of the Start value Freq< setting, the frequency gradi-
ent protection is enabled. After the frequency has dropped
below the set value, the frequency gradient is compared to
Start value df/dt setting. When the fre-
the set value of the
quency gradient exceeds the set value, the module activates
the and
START STR_FRG
according to DT. When the operation timer has reached the
Operate Tm df/dt setting, the
value set by the
outputs are activated. If the frequency gradient
OPR_FRG
restores before the module operates, the reset timer is acti-
vated. If the timer reaches the value set by the
Tm df/dt setting, the operate timer resets and the
and outputs are deactivated. The
STR_FRG
put is not active when this operation mode is used.
A consecutive operation is enabled between the protection
methods. When the measured frequency exceeds the set val-
Start value Freq> setting, the frequency gradient
ue of the
protection is enabled. After the frequency exceeds the set
value, the frequency gradient is compared to the set value of
Start value df/dt setting. When the frequency gradient
the
exceeds the set value, the module activates the
outputs. The time characteristic is according to
STR_FRG
DT. When the operation timer has reached the value set by
Operate Tm df/dt setting, the
the
outputs are activated. If the frequency gradient restores be-
fore the module operates, the reset timer is activated. If the
timer reaches the value set by the
ting, the operate timer resets and the
outputs are deactivated. The
when this operation mode is used.
Protection functions
outputs are deactivated.
START
and
OPERATE OPR_FRG
Reset delay Tm df/dt set-
and
START STR_FRG
outputs. The time characteristic is
OPERATE
Reset delay
OPR_UFRQ
START
and
OPERATE OPR_FRG
Reset delay Tm df/dt set-
and
START STR_FRG
output is not active
OPR_OFRQ
Start
and
and
START
out-
and
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